ISSTPapers Cover Design II - 海上技術安全研究所

International Symposium

ON

SHIPBUILDING TECHNOLOGY

(ISST 2007)

- Fabrication and Coatings –

6-7 September 2007

Osaka University, Japan

PAPERS Vol.2

The Japan Society of Naval Architects and Ocean Engineers (JASNAOE)

&

The Royal Institution of Naval Architects (RINA)

International Symposium ON

SHIPBUILDING TECHNOLOGY (ISST 2007)

- Fabrication and Coatings – 6-7 September 2007

Osaka University, Japan

Organized by The Japan Society of Naval Architects and Ocean Engineers (JASNAOE)

and The Royal Institution of Naval Architects (RINA)

Supported by National Maritime Research Institute (NMRI), Japan

and LLOYD’S REGISTER ASIA

© 2007: JASNAOE-RINA JASNAOE and RINA are not, as a bobies, responsible for the opinion expressed by the individual author or speakers. Japan Society of Naval Architects and Ocean Engineers (JASNAOE) Yasaki White Building 3F 2-12-9 Shiba-Daimon, Minato-ku 105-0012 Tokyo, Japan Telephone +81 (0)3 3438 2014 THE ROYAL INSTITUTEION OF NAVAL ARCHITECTS 10 Upper Belgrave Street London SW1X 8BQ, United Kingdom Telephone: +44 (0)20 7235 4622

Shipbuilding Technology ISST 2007, Osaka, 2007

CONTENTS Development of Anti-Corrosion Steel for the Bottom Plates of Cargo Oil Tanks S. Sakashita, A. Tatsumi, H. Imamura and H. Ikeda (Kobe Steel, Japan)

1

Development of Corrosion Resistant Steel for Cargo Oil Tanks K. Kashima, Y. Tanino, S. Kubo, A. Inami and H. Miyuki (Sumitomo Metal Industries, Japan)

5

Development of New Anti-Corrosion Steel for COTs of Crude Oil Carrier S. Imai, K. Katoh, Y. Funatsu, M. Kaneko (Nippon Steel Corporation, Japan), T. Matsubara, H. Hirooka and H. Sato (Nippon Yusen Kaisha, Japan)

11

Onboard Evaluation Results of Newly Developed Anti-Corrosion Steel for COTs of VLCC and Proposal for Maximum Utilization Method S. Imai, K. Katoh, Y. Funatsu, M. Kaneko (Nippon Steel Corporation, Japan), T. Matsubara, H. Hirooka and H. Sato (Nippon Yusen Kaisha, Japan)

21

Prevention of COT Bottom Pitting Corrosion by Zinc-Prime Y. Inohara, T. Komori, K. Kyono, H. Shiomi (JFE Steel Corporation, Japan) and T. Kashiwagi (Mitsui O.S.K.Line, Japan)

29

Development of Corrosion Resistant Steel for Bottom Plate of COT Y. Inohara, T. Komori, K. Kyono, K. Ueda, S. Suzuki and H. Shiomi (JFE Steel Corporation, Japan)

33

The Third Generation Shop Primer and Japanese Shipbuilding Construction Process Y. Seki, K. Kondou and O. Harada (Chugoku Marine Paint, Japan)

37

The Development of Water Based Shop Primers M. Hindmarsh (International Paint, Japan)

45

Coating Conditions in Water Ballast Tank, Void Space and Cargo Oil Tank of Aged Ships and Required Performance Standard of Protective Coatings for New Ships T. Murakami, T. Sasaki, M. Kuwajima, M. Koori (Shipbuilders' Association of Japan), A. Takada and M. Oka (National Maritime Research Institute, Japan)

51

Pitting Corrosion on Epoxy-Coated Surface of Ship Structures T. Nakai, H. Matsushita and N. Yamamoto (Class NK, Japan)

59

Compositional Analysis of Soluble Salts in Bresle Extraction from Blocks in Newbuilding Shipyards S. S. Seo, S. M. Son, C. H. Lee and K. K. Baek (Hyundai Heavy Industries, Korea)

65

Effect of Edge Preparation Methods on Edge Retention Rate of Epoxy Coatings for Ship's Ballast Tanks S. S. Seo, K. K. Baek, C. S. Park, C. H. Lee and M. K. Chung (Hyundai Heavy Industries, Korea)

71

© 2007: JASNAOE-RINA i


Study on the Alternatives to the Secondary Surface Preparation in Protective Coatings N. Osawa (Osaka University, Japan), K. Umemoto (Kawasaki Shipbuilding Japan), Y. Nambu (Universal Shipbuilding, Japan) and T. Kuramoto (Mitsui Engineering and Shipbuilding, Japan)

77

Leaching Phenomena of Antifouling Agent from Ship Hull Paint R. Kojima, O. Miyata, T. Shibata, T. Senda (National Maritime Research Institute, Japan) and K. Shibata (Chiba Institute of Technology, Japan)

85

Space and Time Distribution of Antifouling Agent in Aquatic Environment K. Shibata (Chiba Institute of Technology, Japan), V. A. Sakkas (University of Ioannina, Greece), S. Sugasawa, Y. Yamaguchi, F. Kitamura and T. Senda (National Maritime Research Institute, Japan)

93

Acute Toxicity of Pyrithione Photodegradation Products to Some Marine Organisms T. Onduka, K. Mochida, K. Ito, A. Kakuno, K. Fujii (National Research Institute of Fisheries and Environment of Inland Sea, Japan) and H. Harino (Osaka City Institute of Public Health and Environmental Sciences, Japan)

99

Research for the Risk Assessment of Anti-Fouling System E. Yoshikawa (Chugoku Marine Paint, Japan), N. Nagai (Japan NUS), K. Namekawa (Arch Chemicals Japan), K. Shibata (Chiba Institute of Technology, Japan) and T. Senda (National Maritime Research Institute, Japan)

107

The Benefits of Foul Release Coatings I. Walker (International Paint Japan)

117

Antifouling Systems to Reduce Biocide S. Tashiro, M. Doi, Y. Kiseki and M. Ono (Chugoku Marine Paint, Japan)

121

A New Prediction Method for Deterioration of the Corrosion Protection System of the Oil Storage Barges H. Sugimoto (Shipbuilding Research Centre of Japan) and Y. Horii (Japan Oil, Gas and Metals National Corporation, Japan)

127

Matching the Coating Process to Shipyards Needs R. Kattan (Safinah Ltd., UK)

133

SI Technology and its Unique Paint Property N. Sasaki and M. Takayama (Nippon Paint Marine Coatings, Japan)

141

Corrosion Protection Regulations to Improve Ship’s Safety? T. Lohmann and D. Engel (Germanischer Lloyd, Germany)

145

Class NK's Course of Action to Protective Coating - Guidelines for Performance Standard for Protective Coating Contained in IMO Resolution MSC.215 (82) T. Matsui (Class NK, Japan)

149

© 2007: JASNAOE-RINA ii


© 2007: JASNAOE-RINA 85

LEACHING PHENOMENA OF ANTIFOULING AGENTS FROM SHIPS!HULL PAINTS

*Ryuji KOJIMA, Osamu MIYATA, Toshiaki SHIBATA and Tetsuya SENDA, National Maritime Research

Institute, Japan

Kiyoshi SHIBATA, Chiba Institute of Technology, Japan

SUMMARY

The effects of pH, dissolved ion content and relative water velocity on the release rate of an antifouling agent, cuprous

oxide, from ships’ hull paint have been investigated by rotating cylinder tests. Additionally, test paint panels were

attached to a vessel and recovered after a certain period of voyage for the validation of the laboratory tests. In the initial

period, the release rates are influenced by pH, dissolved ion content and water velocity, but once after a certain period of

test, those effects become less significant. These phenomena can be explained as follows. When the paint film is fresh,

the rate is controlled by chemical reaction, the surface and/or diffusion layer in the water phase governs the rate. After

the antifouling substance in the paint film leached out from the near-surface region, a diffused layer (leached layer), that

has little antifouling agent remained, is formed at the surface of the coating, and the diffusion in that layer can be a rate-

determining process. The development of the leached layer is affected by a balance between the leaching rate of the

antifouling ingredient and paint resin determined by the chemical properties and speed of the water. Thus, the leaching

rates of antifouling agents are affected by the history of the paint in the water.

1. INTRODUCTION

The deleterious effects from the unwanted

accumulation caused by the chemical substances have

been much attention as aquatic environmental problems

for many years. A significant route of exposure into an

environment is entry of antifouling agents into the ocean

environment as they are released from paint coatings, and

the deleterious effects of the ships’ hull paint have been

recognised [1]. Therefore, a leaching rate of antifouling

ingredient is a critical parameter for the environmental

risk assessment in a calculation of predicted environ-

mental concentration (PEC) values. In order to obtain the

PEC values of antifouling ingredients from ships’ hull

paints, it is necessary to estimate the leaching rate of

antifouling ingredients from ships particularly when they

voyage or berth in a harbour and an inland sea. Therefore,

release rates of antifouling ingredients from the coatings

of ships’ hull are required by a number of regulatory

authorises according to American Society for Testing and

Materials (ASTM) and the International Standard

Organization (ISO) which codify the methods to measure

the release rate of an antifouling ingredient into the

aquatic environment [2, 3, 4].

The test method, however, has not yet been

validated to reflect the release rate of antifouling

ingredients from coatings. Therefore it should not be

used in the process of conducting environmental risk

assessments at present. Furthermore, the test method

serves only as a guide for characterization of the early

stage of the release as well as estimating the steady state

leaching rate of antifouling ingredients from coatings.

Further, it is stated in ISO (15181-1) that actual release

rate of antifouling ingredients from ships’ hull paints into

the environment will depend on many factors such as

ship operating schedules, length of service, berthing,

conditions, paint condition, as well as temperature,

salinity, pH, pollutants and bacterial effect [5].

At the National Maritime Research Institute

(NMRI), various test methods have been investigated to

determine the release rate of antifouling coatings, for

examples, the circulation channel and the rotating

cylinder methods, in order to obtain more meaningful

data for the evaluation of environmental risk assessment

factors. As for the rotating cylinder tests, it has been

found that the release rate is influenced by pH, dissolved

ion content and the rotation speed of test cylinder [6].

Fig. 1: Photograph of the rotating cylinder test apparatus:

the test cylinder holding tank is on the left and the test cylinder measuring tank is on the right.

Fig. 2: Photograph of each individual measuring container

in the measuring tank. The effects of pH, dissolved ion

content or rotation speed of test cylinder on the leaching rate of antifouling agents are investigated at this stage.



However, the leaching phenomena of antifouling

ingredients actually occurring in the ocean are considered

to be much different from those observed in the

laboratory tests [5, 7].

To investigate the leaching phenomena of the

antifouling ingredients, laboratory and field tests have

been carried out to clarify the factors affecting the release

rate. In addition, observations of cross-sections of

coatings by scanning electron microscope (SEM) were

carried out to analyze the leaching mechanisms.

2. EXPERIMENT

2.1 ROTATING CYLINDER TEST

Rotating cylinder tests were conducted

complying with ASTM, D 6442 [2]. Test cylinders are

made of polycarbonate (Nalugene) of 12 cm in height,

and of approximately 6.4 cm in diameter, coated with

commercially available paints A and B (Chugoku Marine

Paints, Ltd.) as a band of 10 cm around the exterior

circumference of the test cylinder to provide paint film of

200 cm2. The paint film can be immersed and rotated in

the release rate measuring container. Prior to the test,

cylinders were once immersed in for 24 hours. The tests

were carried out under specified conditions in rotation

speed of cylinder, chemicals of testing solution

(substituted ocean water (S.O.W.), de-ionized water

(D.I.W.), phosphate buffer solution (P. B. S.)), and pH.

The reason of being selected these test conditions is that

the antifouling ingredients will be affected by dissolved

ion contents, pH and hydrodynamic conditions of

exposure. The test apparatus is shown in Figures 1 and 2.

After the test, the cylinder was placed in a

holding tank which was filled with S. O. W. The

temperature and pH were controlled at 25" and 8.2,

respectively. At a certain period of the holding interval,

the cylinder was transferred from the holding tank to

individual measuring container. The test solution of 1500

ml was controlled at a specified temperature and leaching

conditions as a similar manner to those mentioned above.

The rotation period of the measurement of the release

rate is up to 1 hour. After the measurement, the cylinder

was placed back to the holding tank, and the alternate

process of immersion of holding tank and the

measurement of release rate was repeated. In addition,

the standard test conditions were settled at a rotating

speed of 60 r. p. m. and a temperature of 25" in S. O. W.

solution. The release rate was determined by measuring

the concentration of copper in the resultant test solution

by atomic absorption spectroscopy (AAS).

Table 2. The anticipated effects on the leaching rate of

antifouling ingredients

Effective Factors1)

Rotation Speed

Ions

pH

Historical Records

of Immersion3)

0, 30, 60, 180 r.p.m, respectively

Substitued Ocean Water (S.O.W.), De-

ionized Water (D.I.W), and Phosphate

Buffer Solution (P.B.S.)2)

7 , 8, and 9 (Controlled by dil. HNO3 and

NaOH of 0.1N)

Rotation Speed, Ions, and pH

1) The test solution was prepared at pH 8.2 exception of pH

experiment.

2) P.B.S. was prepared by KH2PO4-Na2HPO4.

3) Test cylinders were conducted each case of leaching test

up to 24 hours in advance, respectively.

2.2 THE COATINGS

The tested coatings were the films of the

commercially available anti-fouling paints SGP-500

(designed as Coating A in the present paper) and SGP-

1000 (Coating B) both provided by Chugoku Marine

Paints, Ltd. The both paints contain cuprous oxide

(Cu2O) as a main anti-fouling ingredient. The chemical

compositions of Coatings A and B are shown in Table 1

from the Material Safety Data Sheet (MSDS).

2.3 THE LEACHING RATE OF TEST PANELS

ATTACHED ON THE VESSEL

In order to investigate the leaching phenomena

in actual sea, the release rate of anti-fouling ingredient

Table 1: The formulation of coating (weight mix, wt%)

Formulation

Cu2O

ZnO

Xylene

Ethylbenzene

n-Buthylalcohol

Propylene glycol monomethylether

TiO2

Copper pyrithione

Coating

A B

45-50 45-50

5-10 5-10

8 16

9 12

1-5 -

5-10 -

- 5

1-5 1-5

) These data are derived from MSDS of Chugoku Marine

Paint, Ltd.

Fig.3: Photograph of the attachment of test panel at the bilge

keel of Seiun Maru (a training vessel, National Institute for Sea Training). Paints A and B were coated on the panel.



from the test panels attached on a ship’s hull was

measured. Flat panels were prepared for Coatings A and

B on steel plates of 500mm squares with a thickness of

2mm. The plates were first sandblasted and then coated

with a zinc-rich primer on the surface. Antifouling paints

A and B were coated in a similar way as for cylinders.

The flat panels of each paint were attached on the center

position of bilge keel of the ship named Seiun Maru (a

training vessel, National Institute for Sea Training), as

shown in Figure 3. The test paint panels were recovered

after a voyage for six months. The release rate was

calculated as follows; mass concentration of copper in

the paint films was analyzed by X-ray fluorescent

spectroscopy, as shown in Table 3. The thickness of the

paint film was measured by a film thickness meter of

electromagnetic detection before and after the test. Mass

loss was obtained from the thickness reduction using the

specific gravity of the paint film, and then mass of the

leached copper was calculated.

2.4 THE LEACHING RATE OF STATIC

CONDITION RECOVERD FROM TESTS PANEL ON

THE SHIP

Another test was conducted to measure the

release rate under a static condition for two types of

panels with different situations, that is, an as-coated

panel (for control) and one after voyage for six months,

as shown in Figure 4. Before testing, the surface of the

latter one was cleaned by tap water. In order to measure

the release rate of antifouling ingredients, the panels

were immersed in S.O.W. of 20L controlled at pH 8.2 at

room temperature, and were settled in a horizontal

position with a downward direction for the paint surface

facing to S.O.W directly. The test solution was sampled

during a given time of immersion (0 hour and every 1

hour, up to 4 hours), and followed by AAS to analyze the

concentration of copper. Immersions were conducted up

to 10 days, under specified conditions by exchange

S.O.W. every day.

2.5 THE OBSERVATIONS OF CROSS-

SECTONAL SURFACE OF TEST CYLINDER BY

SEM

The test specimens were observed by SEM, as

shown in Figure 5. After the measurement of release rate

for 45 days, the test cylinders were sawed across the

paint film to give specimens. The specimens were

molded in resin, and polished. The polished cross-

sections were observed by SEM in a back-scattered

electron image mode.

3. RESULTS AND DISCUSSIONS

3.1 THE EFFECTS OF ROTATION SPEED OF

TEST CYLINDER ON THE RELEASE RATE OF

ANTIFOULING AGENTS

Firstly, the effects of rotation speed of test

cylinder varying from 0 rpm to 180 rpm on the release

rate are shown in Figures 6 and 7, where the variation of

Figure 4: Photograph of the leaching rate test method for flat

panels under static conditions using fresh panels as control

and panels recovered from the Seiun Maru (pH 8.2, room temperature).

Fig. 5: The back-scattered electron image mode by SEM at

1000-fold magnification. White colored images show the antifouling agents as cuprous oxide.

The leached layer

The Paint film layer contained

antifouling agents

Elements

BC

O

Mg

AlSi

P

S

Cl

CaFe

Ni

Cu

Zn

As

Sn

Paint (mass%)

A

2.2734.12

25.08

1.42

0.17

1.08

0.01

0.84

1.36

0.030.40

0.02

27.75

5.39

0.02

0.06

B

-30.28

25.34

1.18

0.14

2.78

0.01

0.58

0.23

0.350.35

-

34.96

3.82

-

-

Table 3: Elemental analysis of paints in the experiment



the release rate of copper was illustrated as a function of

the immersion time. For the both coatings, the leaching

rate of copper increased gradually with an increase in

rotation speed of cylinder in an early stage of immersion

duration up to the 25th day. In the case of 180 rpm for

both coatings, release rates are almost 4 times higher

than those in case of 0 rpm. It should be noted that even

in the 0 rpm, copper was released gradually. However,

the release rate of copper gradually decreased during the

immersion after the 30th day, where it still remained

being affected by the rotation speed of cylinder [8].

3.2 THE EFFECTS OF pH AND DISSOLVED

ION SPECIES ON THE RELEASE RATE OF

ANTIFOULING AGENTS

The effects of pH and dissolved ion species on

the release rate of copper at a rotation speed of 60 rpm

are shown in Figures 8 and 9 for Coatings A and B,

respectively. These figures show the variation in the

release rate of copper as a function of the immersion time.

In the both coatings, low pH (at pH 7) showed a great

influence on the leaching rate of copper at the initial

stage of immersion period (the first day). It showed

almost 10 times higher than other factors with an

exception of the case in P.B.S of coating A. However,

the release rate of copper decreased significantly at the

third day and gradually decreased during the immersion

test. The release rate of copper for both coatings showed

similar values at a later period of test, e. g., at the 28th

day, independent of pH and dissolved ion content [8].

3.3 COMPARISON OF RELEASE RATE

BETWEEN LABORATORY TEST (ROTATING

CYLINDER TEST) AND FIELD TEST (FLAT PANEL

TEST)

The flat panel tests were conducted using a ship

named Seiun Maru. The distance of voyage and

temperature are illustrated in Figure 10 [9]. Generally,

the thickness of film decreased more for a longer period

of voyage, and the decrease rate of film thickness

depended on both the average speed of the ship and the

temperature of ocean water.

The comparison of the release rate with or

without water flow rate between the rotating cylinder test

(60 rpm; flow rate, 0.4m/s) and the field test was shown

in Figures 11 and 12, respectively. The authors obtained

some results are summarized as follows:

• The release rate of copper decreases with

increasing test period.

• The release rates of antifouling ingredient from

coatings A and B are affected by flow rate of water.

• The release rate of antifouling ingredient of coating

B is much higher than that of coating A.

• The release rate obtained by the cylinder test when

the test period is long is almost equivalent to that

by the field test.

3.4 THE MECHANISM OF LEACHING OF

ANTIFOULING AGENTS

Fig. 8: The variation in the leaching rate of coating A as a

function of immersion period of test cylinder during a given time up to 28 days in various effects.

Fig. 9: The variation in the leaching rate of coating B as a

function of immersion period of test cylinder during a given time up to 28 days in various effects.

Fig. 6: The variation in the leaching rate of coating A as a

function of immersion period of test cylinder during a given time up to 45 days.

Fig. 7: The variation in the leaching rate of coating B as a

function of immersion period of test cylinder during a given time up to 45 days.



3.4 (a) The observation of the cross-section of

specimens by SEM

The cross-sections of specimens were observed

by SEM. Figures 13 to 16 show the cross-sectional

images of paint films after the leaching tests. In each

coating, except for the case of coating A in PBS, a

leached layer, where cuprous oxide particles were not

present, was observed at the surface of the coating.

Thicknesses of the layers with and without copper

content were measured on these images. These results are

summarized in Table 3.

3.4 (b) The mechanism of leaching rate of antifouling

agents

In the case of rotating cylinder tests as

mentioned above, these phenomena can be explained as

follows. In the initial stage of leaching, the release rate of

antifouling agents is affected both by the resistance of

diffusion in the laminar film and by dissolution of

antifouling agents at the interface between the coating

and water. When the copper near the surface has been

leached out, remaining polymer forms a skeleton

Fig. 11: The comparison of the leaching rate without water

flow between rotating cylinder test, field test of flat panel and

laboratory test of flat panel recovered from field test. Open

triangle, circle, square, and closed circle symbols mean the

leaching rate in the case of laboratory conditions, and closed

triangle and square symbols mean the leaching rate of field

tests, respectively.

Fig. 12: The comparison of the leaching rate with water flow

between rotating cylinder test and field test of flat panel.

Open triangle and square symbols mean the leaching rate of

rotating cylinder test of laboratory, and closed symbols mean the leaching rate of field tests, respectively.

Fig. 10: Profiles of voyage distance and temperature of

ocean water of Seiun Maru situation in 2007.

A

B

Run rpm

Test

Solution pH

1

2

3

4

1

2

3

4

5

1

2

3

4

1

2

3

4

5

0

30

60

180

60

0

30

60

180

60

SOW

DIW

PBS

SOW

SOW

SOW

SOW

DIW

PBS

SOW

SOW

SOW

8.2

8.2

8.2

8.2

8.2

8.2

8.2

7.0

9.0

8.2

8.2

8.2

8.2

8.2

8.2

8.2

7.0

9.0

Thickness of layer(!m)

48.7

25.0

31.0

24.0

33.0

48.0

64.3

100.7

49.7

36.3

54.7

75.3

51.0

62.3

107.0

64.7

78.7

98.0

27.3

10.0

16.0

24.3

4.3

0.0

8.3

13.0

7.7

17.0

11.7

14.3

20.0

5.0

4.0

6.7

5.0

4.7

76.0

35.0

47.0

48.3

37.7

48.0

72.7

113.7

57.3

53.3

66.3

89.7

71.0

67.3

111.0

71.3

83.7

102.7

(1) (2) (1+2)

Table 3. The image of cross-sectional surface of

test cylinder by SEM

(1) (2)

(1+2)

(1)The layer contained

antifouling ingredient

(2) The leached layer

(1+2) Total film thickness



structure as shown in Figure 13. In this stage, cuprous

oxide reacts with water, diffuses within the surface layer

and is released into seawater.

The above scenario suggests that leaching

process changes from the surface reaction in the initial

stage to the diffusion within the leached layer in the later

stages where diffusion within the leached layer, rather

than the chemical reaction between the cuprous oxide

and seawater, should control the release rate.

Whereas, in the case of coating A in P.B.S, as

shown in picture Figure 15 (a), the leaching phenomena

of antifouling agents was quite different from others.

Because the leached layer was not formed in that case,

the surface was always affected by the surrounding of

water, like fresh paint as mentioned above. The

development of leached layer into the coating is affected

by balancing between the leaching rate of antifouling

agents and resin copolymer of coating determined by the

physical and chemical properties of water phase. It was

thought that similar manner of these phenomena could

occur in the case of field tests of flat panel.

4. CONCLUSION

The author investigated the effects of chemical

and physical properties of water phase by various tests.#

The conclusion can be summarized as follows:

• At the initial period in the rotating cylinder tests,

the leaching rates are influenced by pH, dissolved

ion content and water velocity, but after a certain

time period of leaching, those effects become

smaller.

• It is necessary to control the chemical and physical

condition of the aging tank during the aging period

of test in which the leached layer was developed.

• In the field tests, the leaching rate of copper

a)

0rpm

b) 30rpm

c) 60rpm

d)

180rpm

Fig. 13: The images of cross-sectional surface of cylinders in

the case of coating A verified with the rotation speed of

cylinders at the rate from 0 rpm; (a), 30 rpm; (b), 60 rpm; (c)

and 180 rpm; (d) after immersion of the holding tank for 45 days, respectively.

a)

0rpm b)

30rpm

c)

60rpm d)

180rpm


the case of coating B verified with the rotation speed of

cylinders at the rate from 0 rpm; (a), 30 rpm; (b), 60 rpm; (c)

and 180 rpm; (d) after immersion of the holding tank for 45 days, respectively.

a)P.B.S

d)

S.O.W

b) D.I.W.

e) pH7

c) pH9


the case of coating A verified with the chemical property of

water phase, P.B.S.; (a), D.I.W.; (b), S.O.W.; (c, as control),

pH 9; (d), and pH 7; (e) after immersion of the holding tank for 28 days, respectively.

a)

P.B.S

d)

S.O.W

b)

D.I.W.

e)

pH7

c)

pH9


the case of coating B verified with the chemical property of

water phase, P.B.S.; (a), D.I.W.; (b), S.O.W.; (c, as control),

pH 9; (d), and pH 7; (e) after immersion of the holding tank for 28 days, respectively.



decreases with increasing test period, and the

leaching rates of antifouling agents from coatings

A and B are affected by flow rate of water.

• These differences can be largely ascribed to the

different hydrodynamic conditions of exposure; the

immersed panels have been subjected only to tidal

flow, whereas the vessels have alternated between

periods under tidal flow at pier-side and active in-

service periods at the vessel’s operating speed.

• The authors have also conducted tests of flat panels

attached on the keel of a ship Seiun Maru and

recovered the panels after a certain period of

voyage for the verification of the laboratory tests.

The release rate of the cylinder test could be almost

equivalent to that of this field test, as the leaching

period became long.

• But it is recognized that this investigation may be

confined to matters on this experiment of data for

copper release rate. • The different phenomena of leaching rate of

antifouling agents can be explained by the

development of the leached layer, which formed

near the surface of coating.

• The historical record of the coating in aquatic

condition affects the leaching rate of antifouling

agents.

5. ACKNOWLEDGEMENTS

The authors would like to express their gratitude

to Chugoku Marine Paints, Ltd., for preparation of flat

panels and cylinders for tests. The authors are also very

grateful to Mr. Kaneto Watanabe of National Institute for

Sea Training for the field test by Seiun Maru. This study

has been done under the financial support by the Ministry

of the Environment of Japan. This also is funded research

of Ministry of Land, Infrastructure and Transport.

6. REFERENCES

1. Anon, ‘Marine fouling and its prevention’,

Annapolis: Woods Hole Oceanographic Institute,

388 pp., 1952.

2. ASTM. 2005: Standard test method for

determination of copper release rate from

antifouling coatings in substitute ocean water,

ASTM Method D 6442-05, 9 pp.

3. ISO. 2000, ‘Determination of the release rate of

biocides from antifouling paints – Part 1: General

method for extraction of biocides’, International

Standard ISO 15181-1, 2000.

4. ISO. 2000, ‘Determination of the release rate of

biocides from antifouling paints – Part 2:

Determination of copper-ion concentration in the

extract and calculation of the release rate’,

International Standard ISO 15181-2, 2000.

5. A. A. Finnie, ‘Improved estimates of

environmental copper release rates from

antifouling products’, Biofouling, in Press.

6. R. Kojima et al., ‘The effects of Leaching

Conditions on the Release Rate of Anti-Fouling

Agent in Ship Hull Paint’, Proceedings of the 74th

Annual Conference of The Japan Institution of

Marine Engineering, 89 pp., 2006 (in Japanese).

7. J. E. Hunter, ‘Regulation and Registration of Anti-

Fouling Coatings in the European Union’,

Proceedings of International Symposium on

Antifouling Paint and Marine Environment

(InSAfE), 11 pp., 2004.

8. R. Kojima et al., ‘The Leaching Behavior of the

Anti-fouling Agent by Rotating Cylinder Method’,

Proceedings of the 76th

Annual Conference of the

Japan Institution of Marine Engineering, 19 pp.,

2007 (in Japanese).

9. O. Miyata et al., ‘Verification Antifouling Paint

Leaching Rate Measurement between a Laboratory

and on Operating Ship’, Proceedings of the 76th

Annual Conference of the Japan Institution of

Marine Engineering, 21 pp., 2007 (in Japanese).

7. AUTHORS’ BIOGRAPHIES

Ryuji Kojima holds a current position of

Researcher at Environmental Risk Assessment Research

Group, Division of Energy and Environment, National

Maritime Research Institute. He is responsible for the

investigation of leaching rate of antifouling agents by

laboratory test. His previous experience includes

photocatalytic degradation of tributhyltin chloride in the

aqueous solution by titanium oxide coated on the sphere

silica gel, and analytical study of its reaction mechanism

by the semi-empirical molecular orbital calculation

(MOPAC).

Osamu Miyata holds a current position of

Chief Researcher at Environmental Analytical Research

Group, Division of Energy and Environment, National

Maritime Research Institute.

Toshiaki Shibata holds a current position of

Chief Researcher at Environmental Risk Assessment

Research Group, Division of Energy and Environment,

National Maritime Research Institute.

Kiyoshi Shibata holds a current position of

professor, Faculty of Social Systems Science, Chiba

Institute of Technology.

Tetsuya Senda holds a current position of

Director at Division of Energy and Environment,

National Maritime Research Institute.




SPACE AND TIME DISTRIBUTION OF ANTIFOULING AGENT IN AQUATIC ENVIRONMENT Kiyoshi Shibata, National Maritime Research Institute, [Now; Chiba Institute of Technology], Japan Shinobu Sugasawa, National Maritime Research Institute, Japan Yoshitaka Yamaguchi, National Maritime Research Institute, Japan Vasileios A.Sakkas, University of Ioannina, Greece Fumitoshi Kitamura, National Maritime Research Institute, Japan Tetsuya Senda, National Maritime Research Institute, Japan SUMMARY Many of booster biocides in antifouling paints for ship hull pants in present days are photo degradable. In this work, a mathematical model to simulate the concentration change of such booster biocide in the aquatic environment has been developed, taking light irradiation intensity change with time and depth in water column. The calculation results show that the concentration near the water surface becomes low during daytime due to photodegradation reaction, but increases with the water depth. And the concentration even near the surface increases at night. Thus, the concentration oscillates with the change in light intensity by day and night. It implies the possibility of high concentration of the anti fouling agent in deep water, in which the light dose not reaches well due to the absorption of the light by water. NOMENCLATURE C: concentration of antifouling agent (mg/m3) Csat: saturation concentration of antifouling agent in

sea water (mg/m3) Deff,x: effective diffusion coefficient of antifouling agent

in horizontal direction (m2/hr) Deff,z: effective diffusion coefficient of antifouling agent

in vertical direction (m2/hr) I: sun light irradiation intensity (W/m2) I Z=0: sun light irradiation intensity at water surface at

noon (W/m2) I Z=0, t=12: I Z=0: at noon (W/m2) Jx: flux of antifouling agent in horizontal direction

(mg/m2hr) Jz: flux of antifouling agent in vertical direction

(mg/m2hr) kd: rate constant of the photolysis(1/hr) kr: coefficient for the release rate (m/hr) Rr : release rate of antifouling agent from painted

surface (mg/m2hr) t: time (hr) t1/2: half life by photolysis (hr) x: distance from painted surface (m) z: depth from water surface (m)

α: proportional constant of the rate constant to light intensity (m2/hrW)

β: permeability coefficient in equation (8) (1/m) 1. INTRODUCTION Organic tin compounds, such as tri-butyl tin or tri-phenyl tin, were used as effective antifouling agents in ship hull paint. However, their deleterious effects for non-target marine organisms and worldwide contaminations revealed by environmental monitoring studies forced a number of countries and international organizations to ban the use of them in ship hull paint. These regulations have stimulated the development of great numbers of alternative antifouling paints. Most of them consist with copper oxide and various organic booster biocides (hereafter antifouling agent), which are less toxic and

more degradable than the organic tin compounds in the environment, and considered to be more environmentally sound. However, some of them are still very toxic, and their actual degradation performance in the environment is still not clear. Therefore, it is desirable to conduct environmental risk assessment for those antifouling agents. It is a general practice to compare predicted environmental concentration (PEC) and predicted non-effective concentration (PNEC) of the substance to evaluate environmental risk. The PEC calculation is to be made by simulating all related fate process of the substance of interest. In the case of the antifouling agent, it is consisted with numerical modelling of the release rate, diffusion, transportation by water flow, decomposition, adsorption, or other physico-chemical processes in the environment. Among these processes, the photolytic degradation is a unique one, because the light intensity, which is major driving force of the photolysis, is not uniformly applied according to time and position. Thus, the modelling is not simple, though it is said that the photolysis is a predominant decomposition process of many modern antifouling agent. If the photodegradation of the antifouling agent is very fast, the PEC value can be changed drastically, depending on light irradiation intensity which is influenced by the depth and permeability in the water column. That could lead heterogeneous concentration distribution and sensitive change to local environmental conditions. It means the environmental risk itself can vary with time and space. It is necessary to investigate the possibility of fluctuating concentration and effect of related parameters. As a preliminary approach, in this work, a simple mathematical model has been developed to simulate the fate of antifouling agent in aquatic environment. 2. CONSTRUCTION OF PEC MODEL A two dimensional unsteady state model has been developed, simulating the leaching, diffusion and



degradation process of the antifouling agent in a aquatic environment. For some antifouling agents, other fate process, such as biolysis, hydrolysis or adsorption may be significant in the environment, but in this work only photolysis was taken into account, because the photolysis is much faster than other degradation processes for most of the modern antifouling agents, such as Zinc pyrithione (ZnPT), Copper pyrithione (CuPT), and Pyridine tri-phenyl Boron (PTPB).[1, 2] 2.1 MODEL GEOMETRY For simplicity, the modelled water was uniformly 3m deep. And it was assumed that the antifouling agent was released from a vertically placed painted surface, which is 3m deep and horizontally infinite. The released antifouling agent was to be diffused into the water as shown in figure 1.

Figure 1 Schematic View of the 2D Model Water 2.2. RELEASE RATE The release rate of the antifouling agent was expressed as the following equation, assuming the rate is proportional to the concentration difference between saturated concentration and bulk concentration, based on mass transfer theory. This is supported by series of release rate measurement using rotating cylinder.[3]. Rr = kr (Csat – C) (1) 2.3 TRANSPORTATION AND DIFFUSION The released antifouling agent diffuses to vertical and horizontal directions, and transported by water flow. In this model, stagnant water flow was assumed, and transportation of antifouling agent by water flow was neglected, because small enclosed poorly flushed harbours or marines are considered as high risk area. The flux of the antifouling agent caused by eddy diffusion was taken into account, which is expressed using effective diffusion coefficients. In this model, the horizontal direction means only vertical to the painted surface, since infinite painted surface was assumed. Jx=Deff,xdC/dx (2)

Jz=Deff,zdC/dz (3)

2.4 DEGRADATION 2.4 (a) Photodegradation Kinetics

Only photodegradation was taken into account in this model, though the hydrolysis, biolysis or adsorption may contribute significantly in some cases. Yamaguchi et al have reported that the photodegradation rates of ZnPT(Zinc pyrithione), CuPT(Copper pyrithione) [4], or PTPB(Pyridine tri-phenyl Boron)[5] , using Xenon arc lamp with air mass filter to simulate natural sun light irradiation. They concluded that the rate equations can be expressed by the first order kinetics and their rate constants are proportional to the light irradiation intensity. The degradation rate, in this work, was expressed as,

dC/dt = –kdC (4) kd = –αI (5)

Painted surfaceModeled 2D space

Sun light irradiation

Painted surfaceModeled 2D space

Sun light irradiation

The half life is calculated by;

t1/2 = ln 2 / αI (6) 2.4 (b) Light Irradiation Intensity The light intensity at the water surface changes periodically with the time in a day time. It also varies with season, weather and latitude at the place of interest. In this work, only the change during a day was considered as a variable and the intensity was expressed as the following equations. IZ=0=0 0 < t < 6 (7a) I Z=0= I Z=0, t=12 [1－cos{π ( t－6 ) / 6}]/2

6 < t < 18 (7b) I Z=0=0 18 < t < 24 (7c)

The value of I Z=0, t=12 should be selected depending on the season, latitude and weather. In this work, it was assumed to be 0.8, to simulate the light intensity in an averaged summer day of Japan. Sakkas et al[6] have pointed out that dissolved materials in water affect the photodegradation kinetics by generating or absorbing active substances induced by the sun light. But these effects were neglected, and only the effect of decrease of the sun light intensity in water column was taken into account, as described below. The light intensity in water column decreases with the depth of water column. The decreasing rate is dependent on concentrations of phytoplankton, suspended inorganic solids and dissolved organic matters, and wave length of the light as well. Figure 2 shows rearranged plot of measured radiation intensities in the water column based on the data by Kishino[7], and exponential decrease of the light intensity with water depth. The gradient of the light intensity to the water depth depends on the nature of water as well as the wave length of light, as seen in figure 2. The light intensity in 10 depth water is decreased to 1/10 of that close to the surface at coastal



and enclosed bay area. Thus, in this work, the light intensity in the water was expressed as a simple exponential equation, neglecting the dependency on the wave length.

I=I0 10-βz (8) The constant β in equation (8) is indicator of the transparency of the water. Its value is almost 1 in less transparent water and 0.02 in very clear water.

-3

-2

-1

0

1

2

3

0 50 100 150

Depth / m

log

( Int

ensi

ty /1

0-6W

cm

-2 n

m-1

) T, 400nmT, 500nmT, 600nmT, 700nmS, 400nmS, 500nmS, 600nmS, 700nmP, 400nmP, 500nmP, 600nmP, 700nm

Figure 2 Decrease in light irradiation intensity in water column T: Tokyo Bay, Chlorophyll α concentration; 21.5μg/L S: Sagami Bay, Chlorophyll α concentration; 0.66μg/L P: Pacific Ocean, Chlorophyllα concentration; 0.081μg/L 3. CALCULATION

The concentration change of the released antifouling agent with time, depth and distance from the painted surface was calculated numerically. 3.1 CALCULATION PARAMETERS The values of the parameters are listed in Table 1. Table 1 The parameter values for PEC calculation saturation concentration of antifouling agent in sea water Csat: 1000(mg/m3) effective diffusion coefficient in horizontal direction Deff,x:3.6x10-2 and 3.6x10-1 (m2/hr) effective diffusion coefficient in vertical direction Deff,z: 3.6x10-5 and 3.6x10-4 (m2/hr) peak sun light irradiation intensity at sea surface IZ=0,t=12: 0.8(W/m2) proportional constant of the rate constant to light intensity: α:: 7.2(m2/hrW) permeability coefficient in equation (8) β: 0.8(1/m) The release rates of antifouling booster biocides, such

as ZnTP, CuPT or PTPB, are estimated to be several μg/cm2/day. Assuming their content 5 %, paint film

thickness 0.2mm, density of the paint film 2g/cm3 and life of the paint film 4years, average release rate is 1.4μg/cm2/day. The release rate with kr and Csat values, in this work, leads equivalent rate to 2μg/cm2/day. The value of effective diffusion coefficient is depending

on size of eddy which is controlled by local condition. In this work, the effects of the effective diffusion coefficient were examined, changing the values in one order of magnitude. The effective vertical diffusion coefficient was assumed to be 3.6x10-5 and 3.6x10-4 m2/hr. The effective horizontal diffusion coefficient was 3.6x10-2

and 3.6x10-1 m2/hr.

The photodegradation behaviour of ZnPT, CuPT or PTPB has been investigated by several groups of researchers.[1,2,4,5,8,9,10] The reported half life data are scattered in the rage from some minutes to a few days. That is mainly because the light irradiation conditions were not identical. Yamaguchi et al[4, 5] investigated the effect of the light irradiation intensity on the degradation rate, and confirm the first order kinetics and linear relationship between the rate constant and the intensity. That is the base of a part of the model developed in this work, as described in the previous section. Based on their result, the half life of ZnPT is about 20 minutes under 280W/m2 of irradiation, which is yearly daytime averaged intensity in Japan. In this work, the value of α was selected to be 7.2(1/hr) to meet the degradation rate described above. The sun light irradiation intensity at noon sea surface I0 was assumed 0.8W/m2. That is around the average value in Japan. The permeability factor β was evaluated as 0.8, to simulate the water column at coastal aquatic environment, based on the relationship shown in Figure 2. 3.2 RESULT The calculation was started at the midnight and the initial concentration was uniformly zero. Figures 3(a) to 3(c) show the concentration change with time at the points 1m, 5m and 10m from the painted surface, respectively, in 7 days period from starting the leaching form the painted surface. Each line represents the concentration at each depth of the water. The concentration increases during night, due to the continuous release of the antifouling agent, and decreases in daytime with the sun irradiation. The highest and lowest concentrations are achieved at the time of sunrise and just after the noon, respectively. In the afternoon, when the sun irradiation intensity weakens, the concentration rises up again. Even the concentration of the surface water in daytime is almost zero, it is significantly high at night. The similar oscillating pattern of the concentration was established in a few days. The concentration change with time is great near the water surface, because the light intensity is high and its change is more significant than that in deep water. Comparing figures 3(a), (b) and (c), it is clear that the concentration decrease with the distance from the painted



surface, and the concentration difference between day and night is become smaller.

02468

101214161820

0 50 100 150 200Time (hr)

Con

cent

ratio

n (m

g/m

3)

Z=0.05mZ=1.45mZ=2.95m

(a) at the point 1m from the painted surface

(b) at the point 5m from the painted surface

02468

101214161820

0 50 100 150 200

Time (hr)

Con

cetra

tion

(mg/

m3)

Z=0.05m

Z=1.45m

Z=2.95m

(c) at the point 10m from the painted surface Figure 3 Concentration change (Deff,x:3.6x10-3 m2/hr, Deff,z: 3.6x10-5m2/hr)

The concentration profiles against the distance from the painted surface at 6:00 and 12:00 of the 7th day are shown in figure 4. Exponential decrease in the concentration is observed in the figure. The concentration distribution along the depth changes significantly near the surface, due to the fast photodegradation.

02468

101214161820

0 10 20 3Distance from Painted Surface (m)

Con

cent

ratio

n (m

)0

Z=0.05, 6amZ=0.05, 12amZ=1.45, 6amZ=1.45, 12amZ=2.95, 6amZ=2.95, 12am

02468

101214161820

0 50 100 150 200TIme (hr)

Con

cnet

ratio

n (m

g/m

3)

Z=0.05mZ=1.45mZ=2.95m

Figure 4 Horizontal Concentration Profile The calculated vertical concentration profile is shown in figure 5. The gradient against the depth became steeper in the deeper water column. That is corresponding to the decrease of light intensity modelled as the equation (8), base on the data shown in figure 2.

0

2

4

6

8

10

12

0 1 2 3 4Depth (m)

Con

cent

ratio

n (m

g/m

3)

6:00

9:00

3:00

0:00

21:00

15:00

12:00

18:00

Figure 5 Vertical concentration profile Figures 6 and 7 show the concentration change at the point 1m from the painted surface in the 7th day with two sets of the effective diffusion coefficient values, respectively. The higher diffusion coefficient leads the higher concentration at night, but the concentration in day time is in a similar level, in these cases.



0

10

20

30

40

50

0 6 12 18 24Time (hr)

Con

cent

ratio

n (m

g/m

3)

Z=0.25mZ=1.15mZ=2.05mZ=2.95m

Figure 6 Concentration Change in the day 7 at the point

1m from the painted surface (Deff,x:3.6x10-2 m2/hr, Deff,z: 3.6x10-4m2/hr)

0

10

20

30

40

50

0 6 12 18 24Time (hr)

Con

cent

ratio

n (m

g/m

3)

Z=0.25mZ=1.15mZ=2.05mZ=2.95m

Figure 7 Concentration Change in the day 7 at the point

1m from the painted surface (Deff,x:3.6x10-3 m2/hr, Deff,z: 3.6x10-5m2/hr)

4. DISCUSSION The model developed in this work is too simplified to simulate real aquatic environment, and the calculation parameters were hypothetical ones. However, it revealed the possibility of rapid and steep concentration change against time and space, especially along water depth. We cannot expect significant contribution of photodegradatin to the fate process in such water. When the light is weakened in the deep water and photodegradaton rate becomes slow, the biolysis or hydrolysis, as well as adsorption onto suspended particles, would be major fate processes. But, if the rates of biolysis, hydrolysis and adsorption are relatively slow, that is the most case, pilling up of the antifouling agent in deep water is inevitable. Thus, it is important to point out the sensitivity of the photolysis to water column. Most of the environmental monitoring studies have been carried out for the surface water and bottom sediment during daytime. Furthermore, the reported data for ZnPT, CuPT and PTPB in aquatic environment is limited, because of the difficulty in chemical analysis. There have been only one datum reporting the detection of CuPT in sediment.[11] The result in this work suggests that it

might be worth while to examine the concentration distribution along the depth of water column ,or in surface water or at night. The result indicates the difficulties in averaging the concentration to evaluate PEC for environmental risk assessment in such fluctuating situation. If the end point for the assessment is chronic toxicity or long term effect for an actively moving species, it might be adequate to average the concentration over certain time period and special distribution. On the other hand, if it is acute toxicity, the highest concentration in a short time period and narrow point is to be evaluated and the rapid change may cause serious situation. This discussion brings a question on the target of the assessment. What is adequate or proper end point to assess the environmental risk? At present time, many of the environmental risk assessment works have been conducted using just available PNEC data, without taking a position of that specie in targeted eco-system into account. Also, it should be discussed the point or area of the assessment. How close to ship should we approach for the risk assessment? It is obvious that the closer to the ship hull, the higher the antifouling agent concentration. In this work, the calculation parameters, such as photpdegradation rate constant or release rate constant, are evaluated as hypothetical ones, though their order of magnitudes are estimated based on several experimental work. The effect of those parameter values on the calculation results should be examined carefully. The evaluation of such parameters, as well as development of water flow model of real targeted environment, should be a future task. Another important point as a future work is the effect of wave length on degradation rate and contribution of biolysis and hydrolysis in dark water. 5. CONCLUSION A simple model to predict the concentration distribution of antifouling agent in aquatic environment was developed to look into the effect of photodegradation on the concentration distribution. Though the model was too simple to simulate real environment, it has been clearly indicated that the effect of the change in sun light irradiation intensity and penetration of the light in the water column is significant in accumulation of the antifouling agent in water column. The concentration may be seriously high at deep water or at night. If the concentration distribution is steep and changing rapidly as shown in this work, special care has to be paid to select the end point for the environmental risk assessment. 6. ACKNOWLEDGEMENTS The authors would like to express appreciation to the Ministry of Environment for their financial support, and post-doctoral fellowship program of Japanese Society for



9. K.Maraldo and I.Dahllof, Indirect estimation of degradation time for zinc pyrithione and copper pyrithione in seawater, Marine Pollution Bulletin, 48(2004), 894-901

the Promotion of Science which enabled V.A.Sakkas to join the project.. 7. REFERENCES 10. P.A.Turley, R.J.Fenn and M.E. Callow, Pyrithiones

as antifoulants: P.A. Turley R.J. Fenn; J.C. Ritter and M.E. Callow Pyrithiones as antifoulants: Environmental Fate and loss of toxicity, Biofouling, Vol.21, (2005), 31-40

1. P.A.Turley, R.J.Fenn and C.Ritter, Biofouling, Vol.15(2000), 175-182 2. R.L.Amey and C.Waldron, Efficacy and Chemistry of BOROCIDETMP triphenylboron-pyridine, a non-metal antifouling biocide, Proceedings for International Symposium on Antifouling Paint and Marine Environment, Tokyo, (2004), 234-243

11. H.Harino, S.Midorikawa, T.Arai, M.Ohji, N.D.Cu and N.Miyazaki, Cocnentration of booster biocides in sediment and clams from Vietnam, Jounal of the Marine Biologicl Association of U.K., 86(2006), 1163-1170 3. R.Kojima, T.Shibata, O.Miyata, K.Shibata and

T.Senda, The effects of leaching condition on the release rate of anti-fouling agent in ship hull paint, Proceeding for the 74th Symposium of Japan Institution of Marine Engineering (2006), 89-90

8. AUTHORS’ BIOGRAPHIES Kiyoshi Shibata is formerly the head of the environmental assessment research group of National Maritime Research Institute. Now he is a professor in department of social system sciences, Chiba Institute of Technology.

4. Y.Yamaguchi, A.Kumakura, M.Ishigami, K.Shibata, T.Senda and Y.Yamada, Proceedings for International Symposium on Antifouling Paint and Marine Environment, Tokyo, (2004), 228-233

Shinobu Sugasawa is a senior researcher in materials research group of National Maritime Research Institute.

5. Y.Yamaguchi, H.Iwashima, H.Harino, Y.Yamada, K.Shibata and T.Senda, .Photo-degradation of pyridine-triphenylborane, Abstracts for International Chemical Congress of Pacific Basin Societies, Honolulu, (2005)

Yoshitaka Yamaguchi is a senior researcher in environmental analysis research group of National Maritime Research Institute. 6. V.A.Sakkas, K.Shibata, S.Sugasawa, Y.Yamaguchi

and T.Albanis, Aqueous phototransformation of zinc pyrithione Degradation kinetics and byproduct identification by liquid chromatography-atomospheric pressure chemical ionization mass spectrometry, J.Chromatography A,1144(2007), 175-182

Vasileios Alexios Sakkas is a lecturer in department of Material Science and Engineering, University of Ioannina, Greece Fumitosi Kitamura is the director of energy and environmental assessment department at National Maritime Research Institute. 7. M.Kishino, “Interrelationships between light and

phytoplankton in the sea”, In Ocean Optics, Oxford University Press, New York, pp73-92(1994)

Tetsuya Senda is director of energy and environmental assessment department at National Maritime Research Institute. He is responsible for R&D activities on ship related environment protection technologies, monitoring technologies and evaluation methods for the purpose of global-scale environment protection.

8. H.Harino, M.Kitano, Y.Mori, K.Mochida, A.Kakuno and S.Arima, Degradation of antifouling booster biocides in water, Jounal of the Marine Biologicl Association of U.K., 85(2005), 33-38



ACUTE TOXICITY OF PYRITHIONE PHOTODEGRADATION PRODUCTS TO SOME MARINE ORGANISMS

T Onduka, K Mochida, K Ito, A Kakuno and K Fujii, National Research Institute of Fisheries and Environment of Inland

Sea, Fisheries Research Agency, Japan

H Harino, Osaka City Institute of Public Health and Environmental Sciences, Japan

SUMMARY

We evaluated the acute toxicity of zinc pyrithione and copper pyrithione, used as antifouling booster biocides, and their

six main photodegradation products to three marine organisms, representing three trophic levels: an alga (Skeletonema

costatum), a crustacean (Tigriopus japonicus), and a fish (Pagrus major). The acute toxicity values of the pyrithiones for

S. costatum, T. japonicus, and P. major were 1.5–1.6, 23–280 and 9.3–98.2 µg L–1, respectively. The acute toxicity

values of photodegradation products of the pyrithiones such as 2-mercaptopyridine-N-oxide and

2,2′-dithio-bis-pyridine-N-oxide for S. costatum were similar to those of the pyrithiones. These results suggest the

necessity of risk assessments for not only the pyrithiones but also their photodegradation products.

NOMENCLATURE

CuPT: copper pyrithione

EC50: median effect concentration

LC50: median lethal concentration

OECD: Organization for Economic Co-operation and

Development

DMSO: dimethyl sulphoxide

DPS: 2.2′-dithio-bis-pyridine

OTs: organotin compounds

PO: pyridine-N-oxide

POS: 2-mercaptopyridine-N-oxide

POS2: 2.2′-dithio-bis-pyridine-N-oxide

PS: 2-mercaptopyridine

PSA: pyridine-2-sulphonic acid

PTs: pyrithiones

TBT: tributyltin

ZnPT: zinc pyrithione

1. INTRODUCTION

Organotin compounds (OTs) such as tributyltin (TBT)

have been used as effective antifouling biocides [1].

Aquatic pollution resulting from the use of OTs has been

of great concern in many countries, including Japan,

because of its effects on nontarget marine organisms.

Concerns over the toxicity of OTs have led to a

worldwide ban by the International Maritime

Organization. Candidate marine antifouling compounds

developed as alternatives to OTs are Irgarol 1051, diuron,

Sea-Nine 211, zinc pyrithione (ZnPT) and copper

pyrithione (CuPT). In Japan, pyrithiones (PTs) are very

frequently used as antifouling booster biocides, replacing

OT biocides [2]. PTs have been found to have toxic

effects on aquatic organisms, especially algae, at low

concentrations [3–8]. PTs degrade rapidly in the water

column when exposed to light [9,10]. The toxicity of PTs

to aquatic organisms has been clarified, but that of their

photodegradation products, has not yet been elucidated.

The photodegradation products of PTs comprise mainly

six chemicals, 2-mercaptopyridine-N-oxide (POS),

pyridine-N-oxide (PO), 2.2′-dithio-bis-pyridine (DPS),



2-mercaptopyridine (PS),

2.2′-dithio-bis-pyridine-N-oxide (POS2), and

pyridine-2-sulphonic acid (PSA) (Figure 1); a few other

photodegradation products have been reported [11,12].

The purpose of this study was to elucidate the effect of

the degradation products of PTs on marine organisms for

marine environmental assessment. We have already

reported the acute toxicity of CuPT and ZnPT to a fish,

red sea bream (Pagrus major) [8]. In the present study,

we evaluated the 72-h median effect concentrations (72-h

EC50) and the 24-h EC50 of ZnPT and CuPT for an alga

(Skeletonema costatum) and a crustacean (Tigriopus

japonicus). In addition, we evaluated the acute toxicity of

POS, PO, DPS, PS, POS2 and PSA to S. costatum, T.

japonicus and P. major.

Zinc pyrithione (ZnPT) Copper pyrithione (CuPT)

Pyridine-2-sulphonic acid 2-Mercaptopyridine-N-oxide 2.2′-Dithio-bis-pyridine-N-oxide

(PSA) (POS) (POS2)

Pyridine-N-oxide (PO) 2-Mercaptopyridine (PS) 2.2′-Dithio-bis-pyridine (DPS)

Figure 1: Pyrithiones and photodegradation products of pyrithiones selected for toxicity tests

2. MATERIALS AND METHODS

2.1. ANIMALS

Specimens of S. costatum (NIES-324), T. japonicus and

juvenile P. major were obtained from the National

Institute for Environmental Studies (Ibaraki, Japan),

Japan Frozen Food Inspection Corporation (Hyogo,

Japan) and A-marine Kindai Co., Ltd. (Wakayama,

Japan), respectively. Skeletonema costatum was cultured

in 500-mL glass bottle containing 300 mL of f/2 medium

[13], and kept under static-renewal conditions with a

14:10-h light:dark photoperiod at 20 ± 1 °C in a growth

chamber (MLR-350, Sanyo, Osaka, Japan). Tigriopus

japonicus was cultured in a 1-L glass bottle containing

800 mL of filtered seawater with aeration, and fed

Tetraselmis tetrathele under the same photoperiod and

temperature as S. costatum. We captured T. japonicus

nauplius larvae with plankton nets for the acute

immobilisation test. Pagrus major individuals weighing

0.2–0.3 g were maintained for a few weeks in 60-L glass

aquaria at 20–25 ºC under a natural photoperiod and fed

NO

Cu

SN

O

SN

O

Zn

SN

O

S

N SS N

SH

O O

NO

SO3H

N

N S S NN

SH

NO



an appropriate commercial diet once a day until the start

of the toxicity tests.

2.2. TEST CHEMICALS

CuPT and ZnPT were kindly provided by Yoshitomi

Fine Chemicals (Osaka, Japan). POS, PO, PS2 and PS

were purchased from Tokyo Chemical Industry (Tokyo,

Japan). POS2 was purchased from Kanto Chemical

(Tokyo, Japan). PSA was synthesised by Wako Pure

Chemical Industries (Osaka, Japan). All toxicants were

dissolved in dimethyl sulphoxide (DMSO; plant cell

culture-tested, Sigma-Aldrich, St. Louis, MO, USA) to

make stock solutions.

2.3. ALGA GROWTH INHIBITION TEST

The toxicity test was generally performed as

recommended in the test guidelines of the Organization

for Economic Co-operation and Development (OECD)

201, with modification for marine organisms [14]. The

test was performed in glass test tubes (25 × 200 mm, 64

mL), containing 30 mL of f/2 medium. Initial cell

concentrations in the growth media were adjusted to 104

cells mL–1. The in vivo fluorescence of the alga was

measured directly with a fluorescence meter (10-AU-005,

Turner Designs, Sunnyvale, CA, USA) daily. All test

algae were cultured at a temperature of 20 ± 1 °C in a

growth chamber. The light source consisted of three

ultraviolet screening fluorescent tubes (fluorescent lamps

developed for art galleries and museums, Matsushita

Electric Industrial, Osaka, Japan), giving a light intensity

of 40–80 μmol m–2 s–1 and a 14:10-h light:dark cycle.

The test period was 72 h. The test was performed with

three or five concentrations, except solvent controls, in

triplicate. The range of the test solution pH was 7.7–8.9.

The experiments were performed twice. The nominal

concentrations and spacing factors in these tests are

shown in Table 1.

2.4. COPEPOD IMMOBILISATION TEST


recommended in the test guidelines of OECD 202, with

modification for marine organisms [15]. The test was

performed in a 12-well culture plate (Nunc, Roskilde,

Denmark). After the nauplius larvae were washed with

filtered seawater, 2 mL of filtered seawater and five

nauplius larvae were added to each well of the 12-well

culture plate for the toxicity test. Four wells were

prepared for each concentration. The animals were not

fed during the 24-h test period. The tests were conducted

in the dark to prevent photodegradation of the test

chemicals. Immobilisation, defined as the inability to

swim within 15 s after gentle agitation, was checked at

the end of the test. The range of pH of the test solution

was 7.5–7.7. The immobilisation rate of the control

groups of nauplius larvae tested was < 5%. DMSO,

which was used for dissolution of the toxicants, had an

immobilisation effect on copepods at concentrations of

more than 1250 mg L–1. Therefore, we set the nominal

concentration of DMSO to < 1250 mg L–1 in these tests.

The experiments were performed three times. The

nominal concentrations and spacing factors in these tests

are shown in Table 1.

2.5. FISH ACUTE TOXICITY TEST


recommended in the test guidelines of OECD 203, with

modification for marine organisms [16]. The test was

performed in 40-L glass aquaria, containing 20 L of

seawater. This test was conducted with a semi-static

technique; the test solution was aerated and changed

daily. Twenty individuals were used in each exposure

group. The animals were not fed during the 96-h test



period. Mortality was monitored daily. The test was

conducted in the dark to prevent photodegradation of the

test chemicals. The water quality parameter ranges were

as follows: temperature, 23.3–24.0 °C; dissolved oxygen,

5.7–5.9 mg L–1, oxygen saturation, > 80%; and pH, 8.1.

The nominal concentrations and spacing factors in these

tests are shown in Table 1.

2.6. DATA ANALYSIS

For the alga growth inhibition test, 72-h EC50 values

were calculated from the growth rate and the nominal

concentration. The inhibition of the growth rate in

individual test tubes relative to the mean rate for the

controls in each experiment was calculated. The 72-h

EC50 was estimated by probit analysis using the rate of

growth inhibition and the nominal concentration [17].

For the copepod immobilisation test, 24-h EC50 values

were calculated by probit analysis using the

immobilisation rate and the nominal concentration. The

probit analysis was performed with SPSS 14.0J for

Windows regression software (SPSS Inc., Chicago, IL,

USA). For the fish acute toxicity test, 96-h LC50 values

were calculated by the trimmed Spearman-Karber

technique [18] with CETIS software (Ver. 1.0.26C,

Tidepool Scientific Software, McKinleyville, CA, USA)

from the fish mortality and the nominal concentration.

Table 1: Nominal concentrations and spacing factors in toxicity tests Alga growth inhibition test Copepod immobilisation test Fish acute toxicity test CuPT 0.5–2.0 μg L–1 (√2) 6.25–100 μg L–1 (2) ― ZnPT 0.5–2.0 μg L–1 (√2) 62.5–1000 μg L–1 (2) ― POS 0.5–2.0 μg L–1 (√2) 12.5–100 mg L–1 (2) ― POS2 0.5–8.0 μg L–1 (2) 1250–10 000 μg L–1 (2) ― DPS 5–80 μg L–1 (2) 31.3–8000 μg L–1 (2) 50–800 μg L–1 (2) PS 50–800 μg L–1 (2) 1.560–400 mg L–1 (2) 3.13–50 mg L–1 (2) PO 25–100 mg L–1 (2) 25–100 mg L–1 (2) 1–100 mg L–1 (10) PSA 25–100 mg L–1 (2) 25–100 mg L–1 (2) 1–100 mg L–1 (10)

Spacing factors are shown in parentheses.

3. RESULTS AND DISCUSSION

3.1. ACUTE TOXICITY OF PYRITHIONES

The 72-h EC50, 24-h EC50 and 96-h LC50 values of

ZnPT and CuPT for an alga, a crustacean and a fish are

shown in Table 2. The LC50 values of CuPT and ZnPT

for P. major, based on actual concentrations, are cited

from our previous study [8]. The results show that CuPT

is more toxic than ZnPT to crustacean and fish. Among

the three types of organism, the alga was the most

sensitive.

The acute toxicities of PTs to some marine organisms in

our previous study are summarized in Table 3. Acute

toxicity values of PTs for algae, crustaceans and fish

were 0.54–50, 2.5–160 and 7.67–273 μg L–1, respectively.

The EC50 and LC50 values of ZnPT and CuPT obtained

in the present study are similar to the values reported in

Table 3.

Acute toxicity values of TBT for algae, crustaceans and

fishes are 0.33–1.28, 0.6–5.2 and 3.2–25.9 μg L–1,

respectively (Table 4). The EC50 and LC50 values of

ZnPT and CuPT obtained in the present study are similar

to those of TBT, suggesting that CuPT and ZnPT have

similar toxicity to TBT.



Table 2: Acute toxicity of pyrithione transfer products to an alga (Skeletonema costatum), a crustacean (Tigriopus

japonicus) and a fish (Pagrus major), based on nominal concentrations Alga Crustacean Fish 72-h EC50 (μg L–1) 24-h EC50 (μg L–1) 96-h EC50 (μg L–1) CuPT 1.5 23 9.3* ZnPT 1.6 280 98.2* POS 1.1 >12 500 ― POS2 3.4 >1250 ― DPS 65 550 520 PS 730 76 000 45 000 PO >100 000 >100 000 >100 000 PSA >100 000 >100 000 >100 000

*Reported by Mochida et al. (2006); the 96-h EC50 was estimated from the actual average concentration.

Table 3: Acute toxicity data of pyrithiones for marine organisms Class Test organism Toxicity index EC50 or LC50 (μg L–1) Reference ZnPT CuPT Algae Emiliania huxleyi 72-h EC50 0.54 ― [3] Amphora coffeaeformis 96-h EC50 30 50 [4] Skeletonema costatum 72-h EC50 2.06 2.84 [5] Phytoplankton communities various species 1 or 2-day EC50 0.63–19

(2–60 nM) 1.3–7.9

(4–25 nM) [6]

Crustaceans Nitocra spinipes 96-h EC50 178-343 ― [7] Heptacarpus futilirostris 96-h LC50 120* 2.5* [8] Tigriopus japonicus 24-h EC50 160 31 [5] Fish Pagrus major 96-h LC50 273 7.67 [5]

*LC50 estimated using the actual concentration.

Table 4: Acute toxicity data of tributyltin for marine organisms Class Test organism Toxicity index EC50 or LC50 (μg L–1) ReferenceAlgae Thalassiosira pseudonana 72-h EC50 1.03–1.28 [19] Minutocellus polymorphus 72-h EC50 0.33–0.34 [20] Skeletonema costatum 72-h EC50 0.33–0.36 [19,20] Crustaceans Tigriopus japonicus 24-h EC50 5.2 ± 0.5 [21] marine copepod 24-h EC50 2.2 [22] marine copepod 96-h EC50 0.65 [22] Mysidopsis bahia 96-h LC50 1.1 [23] Eurytemora affinis 72-h LC50 0.6 [24] Acartia tonsa 48-h LC50 1.1 [24] Fishes Girella punctata 96-h LC50 3.2 [25] Brevoortia tyrannus 96-h LC50 4.5 [24] Cyprinodon variegatus 96-h LC50 25.9 [24]



3.2. ACUTE TOXICITY OF THE

PHOTODEGRADATION PRODUCTS OF

PYRITHIONES

The EC50 and LC50 values of photodegradation

products of PTs for an alga, a crustacean and a fish are

shown in Table 2. The EC50 values of POS and POS2

for the alga were the lowest among the PT

photodegradation products. The LC50 value of DPS for

the fish was the lowest among the tested PT

photodegradation products. The 24-h EC50 of POS and

POS2 for the crustacean could not be obtained from the

toxicity tests. Because at concentrations of more than

1250 μg L–1 for POS2 and 12 500 μg L–1 for POS, the

concentration of DMSO used as the solvent for the

toxicants was high enough to have an immobilisation

effect on the copepod, we did not perform toxicity tests

with these toxicants at higher concentrations than those

described above. Madsen et al. [26] reviewed the acute

toxicity of ZnPT and three of its metabolites to an alga,

crustaceans, fishes and an oyster. The EC50 and LC50

values of POS2 to the alga, crustaceans, fishes and oyster

were 140, 6.4–13, 30–1100 and 160 μg L–1, respectively.

These values are 2–10 times higher than those of ZnPT

(alga, crustaceans, fishes and oyster: 28, 3.6–6.3,

2.6–400 and 22 μg L–1, respectively) [26]. In that study

[26], the toxicity of POS2 to the alga was similar to that

determined in the present study. However, the 24-h

EC50 value of POS2 for the copepod in this study was

markedly different from the values for crustaceans

(Daphnia magna or Mysidopsis bahia) in the previous

report. This difference might reflect differences in

species sensitivity to POS2.

Our EC50 and LC50 values of PO and PSA for the alga,

the crustacean and the fish were > 100 mg L–1. Reported

EC50 and LC50 values of PSA [26] for the alga,

crustaceans, fishes and oyster were 29, 72–122<,

57–127< and 86 mg L–1, respectively. These data

indicate that the toxicity of PO and PSA to these

organisms is very low. For the copepod, the 24-h EC50

of DPS was the lowest value among the PTs

photodegradation products in the present study.

According to the OECD criteria, substances with acute

toxicity values of less than 1 mg L–1 are classified as

‘very toxic’ [27]. As the lowest toxicity concentrations of

POS, POS2, PS and DPS were less than 1 mg L–1 in the

present study, these four substances are classified as

‘very toxic’. Acute toxicity to the alga decreased in the

order POS ≈ CuPT ≈ ZnPT > POS2 > DPS > PS > PO ≈

PSA. In a study using the rat leukaemic cell viability

assay, the toxicity also decreased in the order CuPT ≈

ZnPT ≈ POS2 > DPS > PO [11]. These results suggest

that the toxicity of PTs diminishes as photodegradation

proceeds.

4. CONCLUSIONS

PTs, like TBT, have been found to have toxic effects on

marine organisms. However, PTs degrade rapidly in the

water column when exposed to light [9,10], and

toxicities of photo-treated PTs decrease [10,28].

Therefore, the environmental risk assessment of PTs has

not been of great concern. In the present study, we

elucidated the toxic influence of PTs and some of their

photodegradation products on an alga, which is one the

primary producers at the base of the food chain in

aquatic ecosystems. The fate of PTs, including under

daytime and nighttime conditions and in subsurface

seawater layer, has not been well studied. Further study

focusing on the degradation of PTs and environmental

risk assessment of PTs and their photodegradation

products is needed.

5. ACKNOWLEDGEMENTS

The authors thank Mr. Yutaka Okumura (Tohoku



National Fisheries Research Institute) for conducting the

alga growth inhibition test; Dr. Satoshi Arima (National

Research Institute of Fisheries and Environment of

Inland Sea) for his advice throughout this work and Ms.

Miki Shoda and Ms. Chiaki Hiramoto (National

Research Institute of Fisheries and Environment of

Inland Sea) for their assistance. This work was

performed with financial support from the Ministry of

the Environment, Japan.

6. REFERENCES

1. FENT K., ‘Ecotoxicology of organotin compounds’, Critical Reviews in Toxicology, 26:1–117, 1996. 2. OKAMURA H., MIENO H., ‘Present status of antifouling systems in Japan: tributyltin substitutes in Japan’ In: Konstantinou I., eds. Antifouling Paint Biocides: Springer, pp 201–212, 2006. 3. DEVILLA R., BROWN M., DONKIN M., TARRAN G., AIKEN J., READMAN J., ‘Impact of antifouling booster biocides on single microalgal species and on a natural marine phytoplankton community’, Marine Ecology Progress Series 286:1–12, 2005. 4. TURLEY P., FENN R., RITTER J., CALLOW M., ‘Pyrithiones as antifoulants: environmental fate and loss of toxicity’, Biofouling, 21:31–40, 2005. 5. YAMADA H., KAKUNO A., ‘Present status on the development of alternative tributyltin-free antifouling paints and toxicity of new biocides to aquatic organisms—Review’, Bulletin of Fisheries Research Agency 6:56–72, 2003. 6. MARALDO K., DAHLLÖF I., ‘Seasonal variations in the effect of zinc pyrithione and copper pyrithione on pelagic phytoplankton communities’, Aquatic Toxicology 69:189–198, 2004. 7. KARLSSON J., EKLUND B., ‘New biocide-free anti-fouling paints are toxic’, Marine Pollution Bulletin, 49:456–464, 2004. 8. MOCHIDA K., ITO K., HARINO H., KAKUNO A., FUJII K., ‘Acute toxicity of pyrithione antifouling biocides and joint toxicity with copper to red sea bream (Pagrus major) and toy shrimp (Heptacarpus futilirostris)’, Environmental Toxicology and Chemistry, 25:3058–3064, 2006.

9. MARALDO K., DAHLLÖF I., ‘Indirect estimation of degradation time for zinc pyrithione and copper pyrithione in seawater’, Marine Pollution Bulletin 48:894–901, 2004. 10. TURLEY P., FENN R., RITTER J., ‘Pyrithiones as antifoulants: environmental chemistry and preliminary risk assessment’, Biofouling 15:175–182, 2000. 11. DOOSE C., RANKE J., STOCK F., BOTTIN-WEBER U., JASTORFF B., ‘Structure-activity relationships of pyrithiones—IPC-81 toxicity tests with the antifouling biocide zinc pyrithione and structural analogs’, Green Chemistry 6:259–266, 2004. 12. NEIHOF R., BAILEY C., PATOUILLET C., HANNAN P., ‘Photodegradation of mercaptopyridine-N- oxide biocides’, Archives of Environmental Contamination and Toxicology, 8:355–368, 1979. 13. GUILLARD R., RYTHER J., ‘Studies of marine diatoms. I. Cyclotella nana Hustedt, and Detonula confervacea (Cleve) Gran’, Canadian Journal of Microbiology 8:229–239, 1962. 14. ORGANIZATION for ECONOMIC CO-OPERATION and DEVELOPMENT. ‘Freshwater Alga and Cyanobacteria, Growth Inhibition Test’, Guideline 201, 2006. 15. ORGANIZATION for ECONOMIC CO-OPERATION and DEVELOPMENT, ‘Daphnia sp., Acute Immobilisation Test’, Guideline 202, 2004. 16. ORGANIZATION for ECONOMIC CO-OPERATION and DEVELOPMENT, ‘Fish, Acute Toxicity Test’, Guideline 203, 1992. 17. FINNEY D., Probit analysis, 2nd ed. Cambridge University Press, 1952. 18. HAMILTON M., RUSSO R., THURSTON R., ‘Trimmed Spearman-Karber method for estimating median lethal concentrations in toxicity bioassays’, Environmental Science Technology 11:714–719, 1977. 19. WALSH G., MCLAUGHLAN L., LORES E., LOUIE M., DEANS C., ‘Effects of organotins on growth and survival of two marine diatoms, Skeletonema costatum and Thalassiosira pseudonana’, Chemosphere 14:383–392, 1985. 20. WALSH G., MCLAUGHLIN L., YODER M., MOODY P., LORES E., FORESTER J., WESSINGER-DUVALL P., ‘Minutocellus polymorphus: A new marine diatom for use in algal toxicity tests’, Environmental Toxicology and Chemistry 7:925–929, 1988.



21. HORI H., TATEISHI M., YAMADA H., ‘Development of acute toxicity test of hazardous chemicals using marine zooplankton as test organism’, Japanese Journal of Environmental Toxicology 4:73–86, 2001. 22. U'REN S., ‘Acute toxicity of bis(tributyltin) oxide to a marine copepod’, Marine Pollution Bulletin, 14:303–306, 1983. 23. GOODMAN L., CRIPE G., MOODY P., HALSELL D., ‘Acute toxicity of malathion, tetrabromobisphenol-A, and tributyltin chloride to mysids (Mysidopsis bahia) of three ages’, Bulletin of Environmental Contamination and Toxicology, 41:746–753, 1988. 24. BUSHONG S., HALL L., HALL W., JOHNSON W., HERMAN R., ‘Acute toxicity of tributyltin to selected Chesapeake Bay fish and invertebrates’, Water Research, 22:1027–1032, 1988. 25. KAKUNO A., KIMURA S., ‘Acute toxicity of bis (tributyltin) oxide to girella (Girella punctata)’, Bulletin of Tokai Region Fisheries Research Laboratory, 123:41–44, 1987. 26. MADSEN T., SAMSØE-PETERSEN L., GUSTAVSON K., RASMUSSEN D., ‘Ecotoxicological assessment of antifouling biocides and nonbiocidal antifouling paints’, Environmental Project Report, 531, Danish Environmental Protection Agency, 2000. 27. ORGANIZATION for ECONOMIC CO-OPERATION and DEVELOPMENT. ‘Guidance document on the use of the harmonized system for the classification of chemical which are hazardous for the aquatic environment’, Series on Testing and Assessment, No. 27, 2004. 28. OKAMURA H., KOBAYASHI N., MIYANAGA M., NOGAMI Y., ‘Toxicity reduction of metal pyrithiones by near ultraviolet irradiation’, Environmental Toxicology, 21:305–309, 2006.

7. AUTHORS’ BIOGRAPHIES

Toshimitsu Onduka currently holds the position of the

researcher in Ecotoxicology Section at the National

Research Institute of Fisheries and Environment of the

Inland Sea, Fisheries Research Agency. He is responsible

for toxic effects of chemicals to marine algae and

crustaceans. His has previous experience in

environmental toxicology and chemistry.

Kazuhiko Mochida and Akira Kakuno are currently

the senior researchers in Ecotoxicology Section at the

National Research Institute of Fisheries and Environment

of the Inland Sea, Fisheries Research Agency. They are

responsible for toxic effects of chemicals to marine

fishes and crustaceans. They have previous experience in

environmental toxicology.

Katsutoshi Ito is currently the assistant researcher in

Ecotoxicology Section at the National Research Institute

of Fisheries and Environment of the Inland Sea, Fisheries

Research Agency. He is responsible for toxic effects of

chemicals to marine fishes and crustaceans. He has

previous experience in environmental toxicology.

Kazunori Fujii is currently the chief of Ecotoxicology

Section at the National Research Institute of Fisheries

and Environment of the Inland Sea, Fisheries Research

Agency. He is responsible for toxic effects of chemicals

to marine fishes and benthos. He has previous experience

in environmental toxicology.

Hiroya Harino currently holds the position of the senior

researcher at Osaka City Institute of Public Health and

Environmental Sciences. He is responsible for detection

of chemicals in environment. He has previous experience

in environmental chemistry.




Research for the Risk Assessment of Anti-Fouling System Eiichi Yoshikawa, Chugoku Marine Paints., Ltd. Keisuke Namekawa, Arch Chemicals Japan, Inc. Noriyasu Nagai, Japan NUS Co., Ltd. Kiyoshi Shibata, Chiba Institute of Technology, Japan Tetsuya Senda, National Maritime Research Institute, Japan

1 INTRODUCTION

In the mid-1970’s, instead of antifouling paint using cuprous oxide (Cu2O), antifouling paints (hereinafter AF paints) using organic tributyltin compounds (hereinafter TBT) were marketed. These compounds improved antifouling performance by leaps and bounds, and extended the dock interval from about 1 year to 5 years, leading to improved economic efficiency. In association with increased usage of TBT, however, because elevation of TBT concentration in the marine environment had been reported and its residue in marine organisms had become an issue in Japanese waters, it became necessary to regulate TBT strictly from around 1990. The diplomatic conference held in the United Nations IMO (The international Maritime organization) headquarters in London from October 1st to 5th, adopted the International Convention on the Control of Harmful Anti-fouling Systems on Ships, 2001 (hereinafter AFS/Conf/26) to phase out TBT on a world-wide basis, which includes a deadline in 2003 for painting and 2008 for the existence of TBT in the antifouling systems on ships. This Convention is expected to enter into force in the middle of 2008. This convention requires the Parties to communicate with the Organization on the information regarding anti-fouling systems approved, restricted, or prohibited under their national law. Also, Resolution 3 invites States to approve register or license anti-fouling systems, urges for the harmonization of test methods, assessment methodologies, and performance standards for anti-fouling systems containing biocides.

2 THE ALTERNATIVE ANTIFOULANTS

TBT-Free AF paints have been developed since 1990, and TBT-free Alternative AF paints are marketed. Alternative biocides used for AF paint in Japan are listed in Table 1. These biocides are controlled by the Law concerning the Evaluation of Chemical Substances and Regulation of Their Manufacture, etc. in Japan.



Table 1 The active ingredients used under JPMA voluntary control of Antifouling system to comply with AFS Convention

Chemical name (IUPAC) [synonym] CAS No. BPD*

Cuprous Thiocyanate 1111-67-7 N

Cuprous oxide 1317-39-1 N

Zinc dimethyl dithiocarbamate [Ziram] 137-30-4 I

3-(3,4-Dichlorophenyl)-1, 1-dimethyl urea [Diuron] 330-54-1 I

Pyridine-triphenylborane 971-66-4 -

N,N-dimethyl-N’-phenyl-N’-(dichlorofluoromethylthio) sulphamide

[Dichlofluanid] 1085-98-9 N

2,3,5,6-Tetrachloro-4-(methylsulphonyl) pyridine 13108-52-6 I

N-(2,4,6-Trichlorophenyl) maleimide 13167-25-4 -

Zinc-2-pyridinethiol-1-oxide [Pyritione zinc] 13463-41-7 N

Copper, bis(1,hydroxy-2(1H)-pyridinethionato O,S)- 14915-37-8 N

2-methylthio-4-tert-butylamino-6-cyclopropylamino-s-triazine 28159-98-0 N

4,5-Dichloro-2-n-octyl-4-isothiazolin-3-one 64359-81-5 N

2,4,5,6-Tetrachloroisophthalonitrile [Chlorothalonil] 1897-45-6 I

Zinc ethylenebis (dithiocarbamate) [Zineb] 12122-67-7 N

Tetramethylthiuram disulphide 137-26-8

1634-02-2 -

* N: Notified, I: Identified. http://www.toryo.or.jp/jp/anzen/imo/index.html

3 THE ANTIFOULING REGULATIONS

The research on the alternatives of TBT AF paints has started actively since 1990 after strict regulation of TBT in Japan, including the investigation of antifouling performance and also its impacts on the environment. The Shipbuilding Research Association of Japan established the SR-209 sectional meeting from 1990 to 1993 to investigate and research new antifoulants that can substitute for TBT. Succeeding to SR-209 from 1997, the Shipbuilding Research Association of Japan established the RR-76 sectional meeting to evaluate the environmental effects of TBT and performance of alternatives. RR-76 is investigating the effects of antifoulants on marine environment including test methods.



Currently Canada, USA, EU, Hong Kong (China), Australia and New Zealand have an antifouling product registration system. Before selling AF paints, the Antifouling must have a risk assessment review for human health (especially the workers exposed at shipyards) and marine environment during application, service life and removal. However the countries with major shipping industries, Japan, Korea, China and the other Asian countries have no specific registration for antifoulants.

4. EU-BPD CONCEPT OF THE ENVIRONMENTAL RISK ASSESSMENT FOR ANTIFOULING SYSTEM

Fig.1 Fate of antifouling ingredients in the marine environment

Active ingredients (hereinafter AI) for antifouling use have a comparatively high toxicity against water organisms. But with this toxicity we expect the efficacy against the biofouling organisms. Technical Notes Guidance (TNsG) of EC directive (98/8/EC) Biocide Product Directive (BPD) indicates that an AI for antifouling use must consider the items shown below.

(1) Degradation AI should be degraded immediately after leaching from ship hull paint and the resultant degradants should have no relevant risk to non-target organisms.

(2) Bioaccumulation An AI should not bio-accumulate in fish or other species to any significant degree, and there should be no secondary poisoning issue through the food chain.

(3) Acceptable toxicity risk assessment The predicted environmental concentration (PEC) estimated from the use of the AF paint coating on ships both within harbours and the shipping lanes must be determined and compared with the

BioaccumulationSediment Settling and Partitioning

BiologicalDegradation

DepositionVolatilization

Aerosol

Leaching

UV Degradation

HydrolysisSpeciation

BiologicalDegradation

Burial

Sorption toparticlate matter

Hydrodynamictransport- tide, currents- density (S)- river flux

Fish, invertebrate, alga



predicted no effect concentration (PNEC) for the specific AI. This comparison should be below 1 for the AI in the AF paint.

(4) Accumulation in Sediments It should be shown that there is no significant accumulation of the AI or its degradants in sediments and that any adsorbed AI or degradants poses no risk for sedimentary organisms.

1) Degradation Ideally an AI is designed to be readily degraded after its leaching from ship-hull paint. The degradation is caused by hydrolysis, photolysis (by sun light) or bio-degradation (by bacteria). According to the BPD TNsG, AI with a half life <15 days (based on full mineralization, that is more than 90% mineralized) in natural water (which contains inherent bacteria) should be considered as ‘readily biodegradable’. According to the criteria under the UNEP-POPs Convention, a chemical has a half life of mineralization > 60 days in marine water should be considered to be a persistent substance. Mineralization is generally contributed by bacteria. The OECD biodegradation studies for estimation of mineralization rate use activated sludge sourced from a sewage treatment plant. But in ship hull paint AIs are released directly to sea water. Therefore a sea water degradation study is required for the use of AIs for antifouling. The number of bacteria in sea water is much lower than that of in the activated sludge. Therefore it is difficult to classify them as readily biodegradable with regard to the marine environment. However, the degradation process for many AIs does not lead to immediate mineralization and, it is also permissible to use some AIs which are rapidly degraded to non-harmful compounds by natural sea water. In that case, the identification and quantification of metabolites are also required. The risk assessments need refinement in relation to these metabolites.

2) Bioaccumulation Bioaccumulation studies often use fish or shellfish as test organisms. The test environment concentrations of the AI in such studies are maintained below the no effect concentration of test substance throughout the test period. The organisms’ tissue samples after several weeks cultured are collected and test substances will be quantified (µg/kg tissue wt.). The result would be used to determine the BCF (Bioconcentration factor) as below.

Test substance in tissue (µg / kg) BCF =

Test substance in water bath (µg / L)



Under BPD TNsG, the acceptable criteria used are BCF < 100 or BCF <1000 if it is readily biodegradable substance.

If BCF does not meet the criteria above, a risk assessment for predators due to secondary poisoning and for human exposed via the environment is necessary. The PBT (persistent, bioaccumulative and toxic substances) assessment approach should be considered case-by-case when a BCF is between 2000 and 5000. AI with a BCF>5000 is basically not acceptable.

3) Calculation of PEC/PNEC ratio AI is acceptable if the predicted environment concentration (PEC) is lower than the predicted no-effect concentration (PNEC). PEC OECD emission scenario document (OECD-ESD) for antifouling introduces existing and newly developed scenarios for service life (and application and removal) for antifouling products used on ship hulls. The PEC is estimated in open sea, shipping lane or commercial harbor indicated in the OECD-ESD. http://www.oecd.org/dataoecd/33/37/34707347.pdf The PEC estimation takes into account emission factors (e.g. leaching rate, shipping intensities, residence times, ship hull underwater surface areas), AI related properties and processes (e.g. Kd, Kow, Koc, hydrolysis, photolysis, bio-degradation), and processes related to the specific environment (e.g. currents, tides, salinity, suspended matter load). AI leaching rate (µg/cm2/day) can be estimated by mass balance method (calculation method), field test, or leaching rate test method within ASTM and ISO.

PNEC PNEC is calculated as below using an assessment factor (AF) and the lowest no effect concentration (NOEC) of the relevant available toxicity data. PNEC= Lowest NOEC / AF AF depends on the number of long-term tests available. If a large number of data sets from long-term test for different species are available, the size of AF can be 10 or lower. With only acute toxicity data, then the AF can be as high as 10,000. The table 2 is cited from the technical guidance document (TGD) on risk assessment in the ECB website.



Table 2 Assessment factors proposed for deriving PNECwater for saltwater for different data sets.

4) Accumulation in Sediments If sediment adsorption is high, it should take account of environmental accumulation. According to BPD TNsG, if the Kp (solid-water partitioning coefficient of suspended matter) is more than 2000, sediment/water degradation study and toxicity test for sediment dwelling organisms for PEC/PNEC sediment are required.

5 DEVELOPING ISO STANDARD ON ENVIRONMENTAL RISK ASSESSMENT FOR ANTIFOULING COATING

ISO TC8/SC2 Japan group is considering proposing such an environmental risk assessment system for antifouling to ISO TC8/SC2. Japan Ship Technology Research Association is steering this project. The concept is based on BPD and adapting it to marine environment. As the marine environment is connected throughout the world, there should be international standard. The required studies are also taking into account the data listed in Annex 3 of the AFS convention. Unique points of the newly proposed system are that 1) ‘Tiered approach’ is introduced, 2) The studies are requested step by step (level system) 3) “Loss of biocidal activity” test is required if AI is not mineralized rapidly in natural sea water. The test method is referred from BPD TNsG.



Table 3 Requirement studies Tier 1 – A risk assessment (PEC/PNEC <1) based upon

1. Bioaccumulation study (Fish/Shell) 2. Degradation study

(a) Hydrolysis (b) Photolysis (c) Bio degradation (Natural sea water)

3. Acute toxicity (a) Fish (b) Invertebrate (c) Alga

4. Chronic toxicity (a) Fish/Invertebrate

Tier 2 Level 1 1. Adsorption / Desorption screening test

Tier 2 Level2 1. Identification & Quantification of degradation products

If necessary,

1. Loss of biocidal activity (Degradation by bioassay ) 2. Sediment/Water degradation half life 3. Refine risk assessment (PEC/PNEC) by means of more chronic data on a

wider range of organisms 4. Risk assessment for predators due to secondary poisoning and for human

exposed via the environment.

1) Tiered approach If an AI is acceptable based on the Tier 1 criteria, it is needless to get further data (Tier 2 data package). Such environmentally low risk AI would be required with only a small data package (Tier 1 level) as incentive. If it is not acceptable, then it goes to tier 2.

Tier 1 Criteria Highest BCF<100 The degradation half life< 15 days Assessment Factor based on number / types of studies PEC/PNEC<1

2) Level system Tier 2 consists of Level 1 and Level 2. If an AI is acceptable at certain criteria of Level 1, it is tentatively allowed for use for a certain period (e.g. up to three years). After this certain period, a Level 2 safety data package is required, and the AI is re-evaluated with the total data package. At Level 2 identification of degradation products is requested, which can be the most expensive environmental study (US$ 0.5-1milion). Therefore data requirements with different levels are particularly helpful for R&D of new AIs.



At Level 2 if necessary, the additional studies could be required as below. Loss of biocidal activity test is requested if an AI isn’t readily mineralized. Sediment/water degradation study is required if the Adsporption/Desorption Kp is below 2000. The risk assessment for predator and human is required if the bioaccumulation is high based on BPD TNsG.

It may also be necessary to determine chronic toxicity levels for a wider range of organisms to reduce the AF to be applied to the AI for risk assessment.

3) Loss of biocidal activity test (Tier 2 Level 2) Most of the existing AIs for AF paint use are transformed to non-harmful compounds by hydrolysis, photolysis or bacteria after leaching from ship-hull. In order to evaluate the decomposed substances, loss of biocidal activity test (Callow & Finlay; 1995) is proposed. This study is required for the AI with more than 60 days of half life of the mineralization. The test protocol is acute toxicity test for algae or invertebrates using the natural seawater aged 2, 5, 7 and 14 days respectively to which AI was dosed at concentration equivalent to the EC80 (LC80) initially. The inhibition over time (%) (0 day is assumed to be 100 % activities) is evaluated for each degradation periods.

6 CONCLUSION

・ ISO TC8/SC2 Japan group is studying a draft environmental risk assessment method for antifouling system to ISO TC8/SC2.

・ Antifouling paint is used in no-border area, marine environment. The data and the risk assessment method should be harmonized globally. Therefore it should be standardized through ISO.

・ The proposed concept and data requirements are mostly harmonized with EU Biocide product Directive.

・ In order to give incentive to low risk active ingredients, tiered approach is introduced. This work has been carried out as a study of the Japan Ship Technology Research Association under the support of Nippon Foundation.

7 REFERENCES 1) Report of investigation and research for new antifoulants, The Shipbuilding Research Association of Japan,

SR-209 sectional meeting 1993. 2) Proc. of the 24th UJNR (US/Japan) Marine Facilities Panel Meeting in Hawaii, November 7-8, 2001, The

Status of the Treaty to Ban TBT in Marine Antifouling Paints and Alternatives, Michael A. Champ 3) Report of investigation and research for the evaluation test methods of antifouling paints including tin-free



antifouling paints, Japan Chemical Industry Association (2001) 4) TNsG Data Requirements ;

http://ecb.jrc.it/Documents/Biocides/TECHNICAL_NOTES_FOR_GUIDANCE/TNsG_DATA_REQUIREMENTS/ccov2000.pdf

5) TNsG on Annex I inclusion ; http://ecb.jrc.it/DOCUMENTS/Biocides/TECHNICAL_NOTES_FOR_GUIDANCE/TNsG_ANNEX_I_INCLUSION/Web_April_2002.doc

6) TNsG on Product Evaluation ; http://ecb.jrc.it/Documents/Biocides/TECHNICAL_NOTES_FOR_GUIDANCE/TNsG_Product_Evaluation.doc

7) Harmonisation of Environmental Emission Scenarios: An Emission Scenario Document for Antifouling, Products in OECD countries, European Commission, Directorate-General Environment, 23 September 2004 ; http://ecb.jrc.it/Documents/Biocides/ENVIRONMENTAL_EMISSION_SCENARIOS/PT_21_antifouling_products.pdf

8) Callow M E, Finlay J A., 1995. A simple method to evaluate the potential for degradation of antifouling biocides. Biofouling.9(2), 153-165.




The Benefits of Foul Release Coatings Iain Walker – International Paint Japan K.K.

As international trade booms, the global shipping industry keeps pace by expanding its fleet and building ever bigger and more powerful ships. Whilst the industry is more energy efficient than other forms of transport such as air, rail and road, with an estimated 300 million tons of fuel consumed annually by the world’s fleet, there is an ever increasing focus on shipping’s environmental impact. At this level of consumption the industry currently emits some 960 million tons of CO2 and 9 million tons of SO2 annually. The International Maritime Organization estimates that without corrective action and the introduction of new technologies, air emissions, due to increased bunker fuel consumption by the world shipping fleet, could increase by between 38% and 72% by 20201.

1 IMO ‘Study of Greenhouse Gas Emissions from Ships’ (The GHG Study), MEPC 45/8, 29th June 2000 The industry has tried to find viable means of energy saving for decades. One way to do this is through the use of antifouling coatings. Antifouling coatings are used to improve the speed and energy efficiency of ships by preventing organisms such as barnacles and weed building up on the underwater hull, restricting the ships movement through the water. If ships didn’t use antifouling coatings, fuel consumption could be increased by as much as 40% - with current fuel use consequently rising by 120 million tons per year to a total of 420 million tons per year. It is estimated that antifouling coatings provide the shipping industry with annual fuel savings of US$30 billion and reduced emissions of 384 million tons and 3.6 million tons respectively for CO2 and SO2 annually. Coating suppliers have supported the shipping industry with pioneering antifouling technology since the introduction of the first self polishing copolymer (SPC) antifoulings in 1974 and their contribution to the fuel efficiency of the global fleet has been hugely significant. However, concerns regarding the effect of tributyl tin (TBT) on certain marine species led coatings suppliers to develop more environmentally responsible solutions and, in 1996, the first commercially available biocide free foul release technology was introduced for fast craft and in 1999 for deep sea, scheduled ships. This biocide free, silicone based technology works on a foul release basis by providing a very smooth, slippery, low friction surface onto which fouling organisms have difficulty attaching. Any which do attach, normally do so only weakly and can usually be easily removed. With proven average fuel savings of 4% and a corresponding reduction in emissions, this original silicone development has become firmly established as the industry benchmark in foul release technology. Now, in 2007, the next generation of foul release technology, which is based on new, unique and patented biocide free fluoropolymer chemistry represents the very latest advances in foul release technology, significantly improving upon the performance of the best silicone based systems. Foul Release Foul Release is the name given to technology which does not use biocides to control fouling but relies on a “non-stick” principle to minimise fouling adhesion. Most Foul Release products



currently available are based on silicone technology and they are typically split into two general categories – those for high-speed coastal vessels operating above 30 knots and those for deep-sea, high activity scheduled ships with speeds greater than 15 - 18 knots. Fluoropolymer Technology Fluoropolymer chemistry represents the very latest advances in foul release technology, significantly improving upon the performance of the best silicone based systems. Exceptionally smooth with unprecedented low levels of Average Hull Roughness (AHR) combined with excellent foul release capabilities and good resistance to mechanical damage means that for the very first time, all vessels above 10 knots can now benefit from foul release technology e.g. Tankers, Bulk Carriers, General Cargo Vessels and Feeder Containers. Benefits include a predicted 6% reduction in fuel consumption and emissions, reduced paint consumption at the next docking, reduced risk of fouling during loading delays and enhanced Corporate Social Responsibility through an improved environmental profile. Fluoropolymer technology also provides excellent performance on high speed / high activity scheduled ships which typically consume significantly more fuel per day (and therefore have higher emissions) than slower vessels. The low surface roughness, good coefficient of friction and advanced surface energy characteristics improves fuel efficiency and reduces slime build-up on Container Vessels, Reefers, LNG/LPG Carriers, Cruise Liners, Ro Ro's and Vehicle Carriers. Launched in March 2007, fluoropolymer technology has already built an impressive track record of over 40 vessels with in-service data validating the fuel and emission savings on a range of vessel types.

Average Hull Roughness The Average Hull Roughness (AHR) of ships is of critical importance. Underwater hulls need to be as smooth as possible for maximum efficiency. If hull roughness is allowed to increase, more power is required to push the vessel through the water - more power means more fuel - more fuel means more money and more emissions. Those vessels unable to increase power to compensate for increased roughness will lose speed resulting in slower transit times or late arrivals. Operators able to quote higher speeds during charter contract negotiation may be able to command higher rates. From measurements carried out on hundreds of vessels, the industry is aware that typical SPC antifoulings have an AHR of around 125 microns whilst silicone based systems are better with an AHR of 100 microns. However, measurements on a number of full vessel fluoropolymer applications have shown that this can be further reduced to around 75 microns providing additional savings for vessel operators. Static and Kinetic Coefficient of Friction Friction is the force that resists the motion of two surfaces in contact e.g. a coated hull in water. The coefficient of friction can be static or kinetic and is defined as the ratio of the ‘friction force to the normal force’. The coefficient of friction is an important measure for foul release coatings. The coated hull that offers the least resistance through water will reduce the power required by the vessel to maintain desired speed.



Fluoropolymer Average Hull Roughness Survey – Container Vessel

Average Hull Roughness = 80.5μm

Sides OverallStbd Port All

Average 83.6 77.4 80.5 80.5Mode 54.0 69.0 69.0 69.0

Hull Roughness for 'Andromeda', Outdocking January 2007 - Sides Only

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When the static and kinetic coefficients of friction are measured and compared (both wet and dry) for silicone and fluoropolymer based systems, the fluoropolymer systems show an average improvement of 38%. Surface Energy: Static Performance Fluoropolymer systems have been formulated to make it very difficult for fouling organisms to adhere to the coated surface. The surface energy has been engineered in such a way that a very unattractive surface is presented to the fouling organism. Surface energy quantifies the disruption of chemical bonds that occurs when a surface is created. It is the interaction between the forces of cohesion and the forces of adhesion which determines whether or not wetting, i.e. the spreading of a liquid over a surface occurs. If complete wetting does not occur, then a bead of liquid will form with a contact angle which is a function of the surface energies of the system. If the surface is hydrophobic then the contact angle of a drop of water will be larger. If the surface is hydrophilic then the contact angle will be smaller. By measuring the contact angle with two liquids, one polar liquid (such as water) and one apolar liquid (such as methylene iodide), the surface energy can be divided into two components – polar and dispersive. This gives a measure of how many polar and dispersive (non-polar) groups there are at the surface. The introduction of polar groups in an otherwise non-polar surface will produce a surface that is amphiphilic i.e. the surface combines both hydrophilic and hydrophobic properties. Fluoropolymer systems provide such an amphiphilic surface. It has been established that marine fouling organisms secrete an adhesive, either of a hydrophobic or hydrophilic nature depending on



the fouling species. By having a balanced amphiphilic surface fluoropolymers can minimise the chemical and electrostatic adhesion between the surface and a wide range of fouling organisms. Surface Energy: Foul Release Foul release properties are particularly important when considering slower speed vessels (<15 knots). These vessels often trade on the spot market and may have static periods awaiting a charter or waiting to discharge/load cargo. The excellent foul release properties of fluoropolymers means that even during exceptionally long periods of inactivity, any fouling attachment can be removed either by the vessel getting under way, or if underwater cleaning is the option selected, then less force is required to remove the fouling resulting in less damage to the coating. The better static resistance and improved foul release properties of fluoropolymers means they are suitable for use on newbuildings during fitting out periods and special procedures have been developed to allow application of these systems during new construction. To fully understand how fouling adheres to submerged surfaces and what force is required to remove them, a coating company “grows” its own barnacles and has developed a sophisticated computer controlled system to apply force to the barnacle - the Barnacle Push Off Apparatus. The equipment measures the peak force required to remove the barnacle but, as all barnacles are different sizes, the area in contact with the coated system must be measured. This is done using a computer controlled camera and results are derived from dividing the peak force (in Newtons) by the barnacle area (in mm2) to give the force per area in N/mm2. Barnacle shear adhesion strength is measured in kPa and fluoropolymers typically required 40% less shear force to remove barnacles in comparison to silicone systems. Resistance to Slime Fouling Certain owners enjoying the benefits of using silicone systems have noticed that slime build-up can occur which may lead to fuel or speed penalties. Fluoropolymer technology integrates advanced surface energy characteristics with an ultra smooth surface to reduce slime build-up by 50%. Savings In terms of fuel efficiency and reduced emissions, fluoropolymer technology offers predicted savings of 2% in comparison to silicone based systems and 6% in comparison to typical SPC antifoulings. The potential exists for even greater savings in comparison to controlled depletion antifoulings. For a single VLCC currently coated with an SPC antifouling, this could mean savings of over 9,300 tons of fuel (US$2.8 million with bunkers at US$300 per ton) and a reduction in carbon dioxide emissions of around 12,000 tons over a five year period. Summary In comparison to typical SPC antifoulings and current silicone based foul release products, the latest fluoropolymer technology offers significant environmental and financial benefits for vessel operators.



Antifouling Systems to Reduce biocide Shinnichi TASHIRO, Masakazu DOI, Yasuyuki KISEKI and Masashi ONO Chugoku Marine Paints, 1-7 Meijishinkai Otake Hiroshima, 739-0652 Japan

Keywords: Hydrolysis, Copper-free, Biocide-free, Electro-conductive, Antifouling, Paint, Biocide, Ship

ABSTRACT

During the past decade, new developments and constant improvements have been made to TBT-free antifouling systems. There are now several commonly used systems: (1) Hydrolyzing polymer resin with Copper and booster biocides, (2) Hydrolyzing polymer resin with Copper-free biocides, (3) Hydrolysis polymer without Biocide, (4) Silicone Polymer, and (5) Electrochemical Prevention. Each antifouling system has its own advantages and disadvantages. Without resorting to a single antifouling technique, a large range of research is important. 1. INTRODUCTION

Since the 1970's, TBT antifouling paints have been used widely because of their excellent antifouling performance. However, because of the severe impact to marine ecosystem was expected by the increased loading of TBT, Japan industry started the self-regulation of TBT since 1992. Japan’s decision has since driven development of TBT-free Antifouling paints.

We are pleased to more closely review the TBT-free Antifouling systems most commonly used today. They are, and can be classified, as follows:

1) Hydrolyzing polymer resin with Copper and booster biocides. 2) Hydrolyzing polymer resin with Copper-free biocides. 3) Hydrolyzing polymer resin without biocides. 4) Silicone Polymer: Biocide-free. 5) Electochemical Prevention: Electro-conductive

The advantages and disadvantages of these systems will be discussed. 2. ANTIFOULINGS WITH CUPROUS OXIDE AND BOOSTER BIOCIDE 2.1 Hydrolyzing polymer resin with Copper and booster biocides

Many ship operators are adopting Hydrolyzing polymer, or so called “Self-polishing TBT-Free” type antifouling for service of 3 or more years.

"Self-polishing TBT-Free" paints, consisting of a hydrolyzing polymer as the resin binder and cuprous oxide and booster biocides such as copper pyrithione and zinc pyrithione as the active substances, have become standard antifouling systems.

At the surface of the paint, active substances are released at a constant rate, a function of hydrolysis polymer technology. The biocide release mechanism of hydrolysis polymers is very close to that of TBT antifoulings.

Fig.1. Mechanism of hydrolysis antifouling paint. Release of antifouling agent occurs gradually.



2.2 Actual performance of TBT-AF and TBT-Free paints Fig.2 (below) shows actual performance of TBT-AF and TBT-Free antifouling paint. Both photographs show

excellent antifouling performance with no marine growth. Self-polishing activity is recognized by the color difference of paints. The color difference contrasts higher paint film thickness areas, caused by overlapping during spray application, and lower film thickness area where paint film has polished away.

This phenomenon is a typical feature of self-polishing type antifouling paint.

Fig.2. Performance of Antifouling systems. Left photo is TBT-AF, right photo is TBT-Free.

Fig.3 is a cross-section SEM (Scanning Electron Microscope) photo of paint film obtained from an operating ship.

The left photo is TBT-AF film and photo to the right is TBT-Free hydrolysis film. In SEM photos heavy elements such as copper are seen as bright-white spots. In each photo's, the left side is where seawater was present and the right side is the ship's hull side. There are some bright-white spots in the paint, but the layer (10 to 20 micrometers) near the surface shows no white spots. This surface layer form which cuprous oxide has leached is called reaction layer.

This reaction layer of TBT-Free antifouling is not bioactive, but this is where the hydrophobic resin changes to a hydrophilic resin and dissolves in the seawater, so the effect relies on dissolution of cuprous oxides form a deeper part of the paint film. The increased thickness of the reaction layer tends to cause a shortage of leaching of cuprous oxide, which is one of causes of fouling. Generally the reaction layer of Hydrolysis type antifouling is very thin compared to conventional systems over time. By analyzing the cross-section we can estimate the paint's performance and durability.

Fig.3. Section photo of TBT-AF (left) and TBT-Free (right) films. 2.3 Advantages and Disadvantages

In comparison with the biocide-free systems, the cost of material and application are economical, moreover the application method is easier than for many biocide-free systems.

By controlling hydrolysis reaction and erosion rate of paint films, these antifouling systems are applicable for all types of vessels.



3. ANTIFOULINGS WITH COPPER-FREE BIOCIDES 3.1 Hydrolyzing polymer resin with Copper-free biocides

Continuous research led to the development Self-polishing TBT-Free Copper-free antifouling systems. Since this technology does not contain copper there is even less environmental loading. This system contains triphenylborone-pyridine salt, which is easily degradable in seawater. 3.2 Actual performance and analysis of cross-section photograph

Fig.4 is an in-service picture of TBT-Free Copper-Free antifouling paint. As this photo indicates, selection of appropriate resins and antifouling agents leads to sufficient antifouling performance without using cuprous oxide.

Fig.4. Performance of TBT-Free Copper-Free antifouling paint.

Fig.5 is a cross-section photo of TBT-Free Copper-Free antifouling paint. Since the antifouling system does not

contain copper, bright-white spots are not seen on SEM photo. Furthermore, no reaction layer is observed.

Fig.5. A cross-section photo of TBT-Free Copper-Free antifouling paint.

3.3 Advantages and Disadvantages

By selecting a degradable antifouling reagent, environmental loading is reduced. In comparison with biocide-free systems, application and paint cost are economical. By changing hydrolysis reaction and erosion rate of a paint film, it is applicable to almost all vessels. Depending on the trading pattern of a ship, the performance is superior to that of copper and booster biocide systems.



4. ANTIFOULINGS WITHOUT ANTIFOULANTS 4.1 Hydrolyzing polymer resin without Biocides

With the increase of environmental concerns, there has been a growing requirement for low-biocide antifouling systems.

Fig. 6 illustrates Biocide-free antifouling systems. Only slime attached on the hull, No barnacles or seaweeds are in evident. This antifouling system is based on Copper-Free antifouling technology. Therefore, special processing is not required.

Fig. 6. Performance of Biocide-free type antifouling system. 4.2 Advantages and Disadvantages

Not having copper and booster biocides allows for an environmentally friendly system. These systems are not suitable for tropical water.

5. FOUL-RELEASE ANTIFOULING SYSTEM 5.1 Silicone resin

Another type of TBT-free technology is a biocide-free silicone polymer foul-release system. On the silicone polymer surface, marine growths have difficulty settling and are easily detached due to the paint film’s low surface energy. Adjusting the surface energy of silicone coatings prevents adhesion of marine organisms. A silicone coating has an extra smooth surface and greater elasticity.

Nowadays, 2 types of silicone resin anti-fouling systems are being marketed. One features a “harder” paint film and is applied to ocean going vessels sailing at speeds in excessive 15 knots, i.e. container carrier, car carrier and Gas carrier such as LNGC and LPGC, and are sailing in world wide service. The second is “soft” type containing silicone oil and applied to coastal ships, yachts, pleasure boats, etc.

There is much market information from other makers about the “harder” type for ocean going vessels. Now we will concentrate on the performance of “soft” type.

Fig.7 shows performance of a soft type silicone resin system. The vessel is in coastal service and operates at of

speed of approximately 12 knots. In the photo, the vessel is slightly fouled, but the fouling was easily removed with the wipe of a hand. 5.2 Advantages and Disadvantages

Biocide-free. Coating material cost is relatively expensive. Is more prone to mechanical damage compared to “hard-film” antifouling systems based on hydrolyzing polymers.

Silicone resin (rubber) film hardness is low and has tendency to be damaged easily on the surface by fenders, scratching, etc. When the surface is damaged, the antifouling performance tends to decrease.

Replacing traditional antifouling is difficult due to high costs. Also full blasting is normal due to the adhesion concerns when over coating traditional antifouling systems.



Fig. 7. Performance of silicone resin type antifouling system. 6. ELECTRO-CONDUCTIVE ANTIFOULING SYSTEMS 6.1 Electrochemical Prevention

The electro-conductive antifouling system is another answer to protection without the use of biocides. With electro-conductive antifouling systems, hypochlorous acid is generated by seawater electrolysation and acts as a disinfectant. Formulation of hypochlorous acid occurs as follows.

Fig. 8 Principle of Electro-conductive antifouling system

Anode part: Cathode part: 2Cl- -› Cl2 + 2e- 2H2O+ 2e- -› 2OH- + H2

4OH- -› O2 + 2H2O + 4e-

Cl- + 2OH- -› ClO- + H2O + 2e-

Although hypochlorous acid is only generated on the anode, the antifouling effect can be demonstrated with both

of electrodes by replacing them at an in fixed time. Electric power is required at only a few dozens of Watts/100m2 in order to prevent marine organisms from adhering. This level of electric power can be generated by solar cells and battery systems. The required quantity of hypochlorous acid is very small and easily decomposed in seawater. Therefore the environmental load can be negligible.

Since there are no active ingredients in the paint or paint film itself, antifouling performance cannot be expected when the current is cut or electro-conductive coating is damaged. Fig. 9 shows actual performance.



Fig. 9. Performance of Electro-conductive antifouling system

6.3 Advantages and Disadvantages

Almost zero-emission antifouling system. Only a small quantity of electric power is required. Complicated application method. Non-conductance coatings are required for steel ship to avoid short-circuiting. This is difficult due to pinholes.

7. CONCLUTION

Since vessels are trading and anchoring in diverse environments, no single antifouling system technology is perfect for all vessel types. Each antifouling system has its own advantages and disadvantages. The antifouling systems introduced at this session still require further development to achieve biocide-free or low risk systems assessed by PEC/PNEC. Without resorting to a single antifouling technique, a large range of research is important. REFERENCES 1) "Report of investigation and research for new antifoulants”, The Japan Ship Research Association the SR-209 sectional meeting 1993. 2) Proc. of International Conference on Technologies for Marine Environment Preservation. Tokyo, Japan Sept. 24-29, 1995 Vol. 1, pp.413-419, Research for New Antifouling Paint, E. Yoshikawa 3) Hisashi Yamada, “Studies on Behavior of Organotin Compounds in Marine Environment and Bioaccumulation by Marine Fish, Report from Bulletin of Fisheries and Environment of Inland Sea, No.1, March 1999 4) Horiguchi T, Shiraishi H, Shimizu M & Morita M. 1997. Imposex in sea snails, caused by organotin (tributyltin and triphenyltin) pollution in Japan: a survey. Appl. Organomet. Chem. 11: 451-455. 5) E.Yoshikawa, Proceedings for Research for Alternative Antifouling Paint, Half-day seminar on Anti-fouling paints for ships - Regulations, Views & Alternatives, 7 Apr 2000, Singapore Shipping Association, Singapore



A New Prediction Method for Deterioration of the Corrosion Protection System of the Oil Storage Barges

Hironori Sugimoto, Shipbuilding Research Centre of Japan (SRC)

Yuji Horii, Japan Oil ,Gas and Metals National Corporation(JOGMEC)

SUMMARY The Kamigoto and Shirashima Oil Storage Bases in Japan have been in operation since 1988 and 1996, respectively. The first one of five oil storage barges at Kamigoto Base installed at mooring site in 1986, and it is almost used for 20 years. However, problems such as prediction of deterioration of the corrosion resistance of barge hull structure and accurate prediction of the durability of the fittings have been left in order to expect in future long-term use considering life cycle maintenance. JOGMEC and SRC carried out the research in order to solve these problems. Corrosion protection system for immersed parts of the Oil Storage Barges consists of both painting and cathodic protection system. In this paper, a new prediction method for deterioration of the corrosion protection system of the Oil Storage Barges is reported.

1. INTRODUCTION Crude oil stockpiling activities in Japan have been carried out both in private sector and in the public sector through JOGMEC. The amount of crude oil stockpiles are now 41 million kl and 48 million kl in private sector and public sector, respectively in 2007. Two of the ten (10) public storage bases are the Kamigoto and Shirashima bases having a storage capacity of 10 million kl correspond to 20 percent of stockpile of the public sector. These two bases, the first of its kind in the world, are very large–scale oil storage systems formed by floating offshore structures where each oil storage barges lined up side by side. The Kamigoto oil storage base has been in operation since 1988. All five storage barges were dry-docked once for detailed inspection and maintenance until 2004. The second dry-docking for each barge started in 2007. The Shirashima oil storage base started operation in 1996 and were inspected, surveyed and repaired in detail one by one at the mooring site after gas-freeing the tanks in 2000 and 2005. In 1997, there is the change of the rule applied to the storage barges, and the system of inspection and maintenance are also changed, in which maximum five(5)-years intervals of Docking Survey for representative barges is ruled.[1],[2],[3],[4]. However, problems such as prediction of deterioration of the corrosion resistance of barge hull structure and accurate prediction of the durability of the fittings have been left in order to expect in future long-term use considering life cycle maintenance.

In this paper, a new prediction method for deterioration of the corrosion protection system consists of painting and cathodic protection in immersed part of the Oil Storage Barges is reported. 2. OUTLINE OF OIL STORAGE BARGES The aerial photograph of the Kamigoto oil storage base is shown in Figure 1. Storage barges and barge mooring facilities are arranged in water area while power generation plant, water supply facilities, other utility facilities and etc. are placed in the land. Floating oil fences have been placed double around storage barges to prevent oil contamination. Breakwaters are also arranged to reduce affection of waves.

Figure 1 Kamigoto Oil Storage Base

The sectional view of the structure of the Kamigoto storage barge is shown in Figure 2. The inside of the barge has been divided into 9 subdivisions by longitudinal and transverse bulkheads. For prevention of crude oil



spill and fire control, the structure system of the partition is the double hull and double bottom structures, and those tanks with are always filled with seawater. In order to prevent the fire in the oil storage tanks, the upper space of oil tanks is filled with inert gas.

Oil Sea water

Inert gas

(L:390m,B:97m,D:27.6m) Figure 2 Structure of Kamigoto Storage Barge

3. DIAGNOSTIC SYSTEM FOR CORROSION PROTECTION SYSTEM 3.1 Corrosion protection system Specification for corrosion protection system of the oil storage barges are as shown in Table 1. 1) Considering stowage condition of oil storage tank, tar epoxy paint (T/E) is applied to ceiling part exposed to inert gas and bottom part exposed to sludge sedimentation. 2) Water sealing tanks are protected by tar epoxy paint (250μm) and cathodic protection system with aluminum anodes (5mA/m2--10 years). 3) Tar epoxy paint (400μm) and cathodic protection system with aluminum anodes (10mA/m2--10 years) are applied to bottom and side shell ( to the draft in a half cargo).

Table 1 Corrosion Protection System for Kamigoto Oil Storage Barges

Location System Oil storage tank Upper T/E 250μm

Middle no paint Bottom T/E 250μm

Water tank

T/E/ 250μm Aluminum anode

Side and bottom shell

Topside P/E 400μm Waterline P/E 400μm

Aluminum Anode Immersed T/E 400μm

Aluminum anode Upper deck IZ 75μm

P/E 100μm P/U 40μm

Noteo: T/E: Hi-built Tar Epoxy Paint P/E: Pure Epoxy Paint

IZ: Inorganic Zinc Paint P/U: Polyurethane paint 3.2 Deterioration pattern of corrosion protection system Tar epoxy paint and cathodic protection system are applied to immersed bottom shell, side shell and water sealing tank, Therefore, deterioration pattern of total corrosion protection performance could be assumed as shown in Figure 3. As far as cathodic protection with enough protective currents density is available, fully protection would be expected in spite of progress of paint deterioration. If anodes have lost current to keep adequate potential, corrosion could have occurred instantaneously in this case. Prediction of life of corrosion protection system is very important technology for those oil storage barges.

Time

Qua

lity

Paint+anode

Full protection Corrosion

Det

erio

ratio

n of

pai

nt

Ano

e de

plet

ion

Full protection

Rep

air

１００％

Time Time

１００％

Figure 3 Deterioration Pattern of Total Corrosion

Performance 3.3 Procedure of diagnosis Deterioration diagnosis flow for the immersed shell plate is shown in Figure 4 , for example.[5],[6],[7]. In deterioration diagnosis of the corrosion protection system, collecting additional data (in periodic investigation and by monitoring in the mooring site ) are required to examine the correct life of the system in addition to data obtained normally in the periodic inspection and survey. Measured data are also correlated to corresponding laboratory test data to predict the life of corrosion protection system. 3.4 Deterioration data Deterioration data (impedance) of the tar epoxy paint immersed in seawater obtained by accelerated aging tests in our laboratory are shown in Figure 5 together with



actual data for Kamigot storage barge obtained in tanks at the time of docking survey. Also current density and paint resistance data for test specimens, actual paint in tank and monitoring specimens are sown in Figure 6.and Figure 7. Data of Loss of anode weight is also obtained in actual tanks. Those test data are correlated to actual data obtained by investigation of the storage barges dry-docked. in order to determine deterioration curves for actual corrosion system. 3.5 Results of prediction for deterioration of corrosion protection system Results of prediction for deterioration of corrosion protection system in one of sea water tanks of the Kamigoto No.1 Barge is shown in Figure.8, for example. In Figure.8, solid line indicates prediction of loss of anode weight in water tank (No.1S) considering of paint deterioration. Loss of anode weight can be calculated by integration of current density of actual tank paint coating, protection area and other factor. Two actual tank data points are obtained in tanks at the time of docking survey in 1997 and 2002. In this case life of anode is predicted about 45 years. In other tanks, these estimated lines vary depend on actual data for each tank.

Accelerated Aging Test (Test Specimens) ・Paint -Impedance -Adhesion. -Current density

Actual Barge Measurement(incl. monitoring specimens)・Paint -Impedance -Adhesion. -Current density (paint resistance)

・Anode -Weight reduction

Deterioration Curve-Impedance

-Adhesion. -Current density (paint resistance, anode weight reduction)

Paint deterioration curve Anode deterioration curve

Estimation of Protection System Life

Deterioration Curve for Actual Barge

Matching with Test Data -Paint resistance -Anode-Weight reduction Acceleration Factor

Figure 4 Deterioration Diagnosis Flow

0 50 100 150 200 250 300 350 400 450100

101

102

103

104

105

106

107

Impe

dan

ce（Ω

m２）

Accelerated Aging Test(Days)

Test Data for sea water tank T/E(250μm）

□ Actual Data for sea water tank (Aug.2002)

Figure 5 Impedance Data of Accelerated Aging Tests and

Actual Tank

0 50 100 150 200 250 300 350 400 450

0

1

2

3

4

5

6

7

8

9

10

11

12

Average

Curr

ent

Den

sity

(mA

/m

2)

Accelerated Aging Test(Days)

Test Data for sea water tank T/E250μm

□ Actual Data for sea water tank (Aug. 2002)

○ Monitoring Data (2004)

Lower bound

Upper bound

Figure 6 Current Density Data of Accelerated Aging

Tests and Actual Tank

0 50 100 150 200 250 300 350 400 450100

101

102

103

104

105

106

107

Pai

nt

Res

ista

nce(

Ωm

２）

Accelerated Aging Test(days)

Test Data for sea water tank T/E250μm

□ Actual Data for sea water tank (Aug. 2002)

○Monitoring Data (2004)

Lower bound

Upper bound

Figure 7 Paint Resistance Data of Aging Tests and



Actual Tank Data

0 5 10 15 20 25 30 35 40 45 50

0

2

4

6

8

10

12

14

0

10

20

30

40

50

60

70

80

90

100

■Actual Data

after 14 years

□ Actual Data

after 9 yearsLoss

of A

node

Wei

ght（

kg）

Operation Years

Upper Water Tank（Ｎｏ．１Ｓ）

2007

(scheduled)

Loss o

f Anode

Weight（

％）

Figure 8 Prediction of Loss of Anode Weight (Example) 3.6 Simulation of corrosion protection system The potential measurement used widely in offshore structures is comparatively simple as monitoring technique of the anticorrosive condition. However, it is difficult to obtain polarization curve of the deteriorated surface of the coated plate in order to estimate the coating condition. Here, simulation of potential of deteriorated surface is carried out using assumed polarization curves. Boundary Element Method is applied to analyze potential for various surface condition and arrangement of anode. Computer Code used in this simulation has been developed by Prof. K. Amaya of Tokyo Institute of Technology.[8]. A simulation model for side and bottom of Kamigoto Oil Storage Barge is shown in Figure.9.

coordinate origin

boundary on sea water

Z

X

Y

13.5(m)

10.0(m)

20.0(m)

10.0(m)

10.0(m)

13.2(m)

boundary on air

6.0(m)

0.0

2(m)

Side wall of shipElement No.1-150

Sacrificial anodes

(Line Element

Radius :0.069(m)

Length :2.0(m)Element No.1277 1278

Bottom wall of shipElement No.151-230

Radius :0.069(m)

Length :2.0(m)Element No.1281,1282

Radius :0.069(m)

Length :2.0(m)Element No.1279,1280

①

②

③

Figure 9 Simulation Model for Outside Shell and Bottom Shell of Kamigoto No.2 Barge

The example of simulation results is shown in Figure 10. It is shown that distribution of potential scatters widely in accordance with progress of deterioration of coated plate. Also it is shown that the potential becomes less-noble at distant position from anode location in case of large deterioration of paint.

0 2 4 6 8 10 12 14

0.70

0.75

0.80

0.85

0.90

0.95

1.00

Potent

ial(-V）

Distance（ｍ）

Paintresistance

（Ωm2）

100

101

102

103

104

105

106

Kamigoto No.2line①Anode

position

Figure 10 Results of Potential Simulation Estimation curve to determine paint deterioration condition is shown in Figure 11. Here, maximum difference of potential is a parameter to decide paint deterioration condition. Degree of deterioration can be easily detected by measurement of maximum and minimum potential in the Oil Storage Bases compared with dry-dock measurement.

1 2 3 4 5

-5

0

5

10

15

20

25

30

3510

110

210

310

410

5

0

25

50

75

100

125

150

175

200

225

250

275

300

325

350

375

400

Kamigoto No.2 Line①ΔV = 660*exp(-log(r)/0.527）

Max

imum

Pote

nci

al D

iffe

rence

,　Δ

V（m

V)

(so

lid lin

e）

Paint Resistance　log(r)　（Ωm2）

Acc

eler

ated

Agi

ng

Tes

t(D

ays)

(bro

ken lin

e)

Paint Resistance　ｒ

Lower bound

Upper bound

Figure 11 Estimation Curve for Determination of Paint Deterioration Condition by Potential Measurement



CONCLUSIONS Conclusions are as follows. (1) Deterioration of master curves of paint system by accelerated aging tests is defined. (2) Actual deterioration data of both painting and anode are collected. (3) Method of determine correlation between master curve by tests and actual barge data by measurement at dry-docked survey is established (4) Prediction of a life of present corrosion protection system of immersed portion of the Oil Storage Barges become possible. (5) Estimation curve to determine paint deterioration condition using potential measurement is established. ACKNOWLEDGEMENT This Research is one of JOGMEC’ Project related to the Oil Storage Barges. This research has been carried out under the Technical Committee of SRC chaired by Prof. Takeshi Kinoshita of University of Tokyo. Authors would like to acknowledge JOGMEC and the members of the Committee. REFERENCES [1] S.Harada. ‘Recent rule development of survey program in service for very large floating structure.’ ,Proc. Int. Workshop on Very Large Floating Structures, VLFS’96, Hayama. Japan, 1996. [2] H.Arai. ‘Consideration on safety assessment of very large floating structures-Classification survey for large-scale oil storage system-‘,. Proc. 24th Meeting of the UJNR Marine Facilities Panel, Hawaii. USA,2001. [3] H.Miyake et al. ‘Research and develpent of inspection and maintenance system for oil storage vessels at mooring site’,. Proc. Int. Workshop on Very Large Floating Structures, VLFS’96, Hayama. Japan, 1996. [4] The Shipbuilding Research Centre of Japan(SRC). Report of study on maintenance, Inspection and repair works of oil storage barges in on-site.1997.( In Japanese). [5] H.Sugimoto and T.Ishizaka 'Prediction of Deterioration of the Corrosion Protection System of Oil Storage Barges’, VLFS 2003. [6] The shipbuilding Research Centre of Japan(SRC). ‘Report of study on long term maintenance System of oil storage barges.2004.(In Japanese)’. [7] The shipbuilding Research Centre of Japan(SRC). ‘Report of study on life cycle maintenance system of oil storage barges.2005.(In Japanese).’

[8] S.Aoki, K.Amaya and M.Miyasawa ’Boundary Element Analysis on Corrosion Problems’, Shokabo Tokyo ,1998.(In Japanese). AUTHERS’ BIOGRAPHIES Hironori Sugimoto, Ph.D. holds the current position of technical general manager at Shipbuilding Research Centre of Japan (SRC). He is responsible for research and design of offshore structures and high speed crafts. Yuji Horii holds the current position of sub-leader of national petroleum stockpiling group at Japan Oil ,Gas and Metals National Corporation(JOGMEC). He is responsible for maintenance of national petroleum stockpiling bases.





MATCHING THE COATINGS PROCESS TO SHIPYARD NEEDS R Kattan, Safinah Ltd, UK SUMMARY “Before I begin on this subject, I shall give a few necessary cautions which ought to be minded in fitting and preparing the parts that are designed to be painted, otherwise your paint, (Which undeniably is a very good Preservative, if rightly apply’d) will be of little Use or Service…..Sutherland: Of painting ship-work 1717”. The coating process has long been considered to have less importance to the shipbuilding process than steel work and outfit work. However as the other processes have become more efficient over recent years, the problems being encountered in the coating activities are increasing. The problems manifest themselves in a number of ways, but increasingly in terms of time, cost and quality. 1. INTRODUCTION The major facility technology developments in shipbuilding took place in the 1960’s and early 1970’s in Japan and Sweden and subsequently Korea, papers written at that time [1, 2, 3] placed heavy emphasis on the development of steelwork activities, with only one of the papers affording some mention of coatings: “The method of surface pre-treatment will be shifted from the mechanical process of shot blasting to a chemical treatment of spraying acid or rust removing chemicals from now on. It is being studied whether to perform this operation after sub-assembly or after completion of hull blocks. The hand spraying method of painting, which is the current practice, may be replaced in the future by electro static spray or flow on painting conducted after sub-assembly or completion of hull blocks, or by the submersion of hull units or blocks in a tank of paint. Another treatment system under study is to pour paint into ships tanks to be coated. In any case, development of new paints themselves and the large quantity of paints to be stored still remain as a problem to be solved” – Takezawa 1972 Since that time there was a steady increase in shipyard investment in steel production and outfit facilities, until by the early1990’s it became clear that the coating process was becoming a bottleneck to shipyard output and production and would result in considerable problems in the integration of the coating process to the much shorter production times [4]. Since 1994, the pace at which productivity has had to be increased to enable yards to remain competitive and the increased in environmental awareness as well as end-user demands have placed considerable pressure on shipyards around the world resulting in real problems in managing the coatings process and making the coating process the bottleneck to production capacity.

2. PROCESS CONTROL Coating activities raise a unique set of problems for shipbuilders, as the processes involved in coating can be subject to considerable variation making the process unpredictable (unstable). The normal shipyard coating processes usually consists of:

Treatment or primer line (sometimes undertaken by subcontractor) Some shop coating work (Fillet welds on the panel line) Secondary surface preparation and coating on block (outside or in workshops) Post erection coating works (erection butts and seams, keel blocks, finish coats and cosmetic coats etc.).

The sources of variance in the processes is primarily from 4 sources:

Unpredictable schedule (weather conditions, Temperature, humidity, dew point etc.). Unpredictable drying times for coatings Interference with other processes resulting in re-work. Subjective nature of acceptance criteria at inspection

The schedule within the paint department is considerably affected by the weather. Even with enclosed workshops, weather can still create problems as if it has been raining, blocks may enter wet or even covered with snow and hence result in additional cycle time needs. If a TACT time of +2σ [5] were to be used to balance the production line then the yard output would be reduced to a level that would not be commercially sustainable. However, it is surprising how often the author visits yards that do not



alter the coating production schedule between summer and winter months. Drying time is subject to considerable variation as a result of:

Poor thickness control Unpredictable temperature

The application process of coatings has largely been based on the airless spray method. As worker skill has decreased (painting is very dirty and relatively lower paid than other shipyard skills, making it hard to retain workers), the paint technology has been changed to enable the paints to be more easily applied (reducing runs and sags). This has in turn resulted in over application of coating, resulting in high thickness and considerably increased drying time with a large variation. The unpredictability of the ambient temperature further increases the variation in the drying time. Enclosed and heated workshops, in theory should reduce the variance, but the practical aspect of the cost to heat these large workshops is often a barrier to their effective use. Depending on ship type and size, shipyards can experience re-work levels in excess of 30% of total man-hours for coating activities (with some Naval yards running nearer 60% of total man-hours for coating activities). Considerable work has been undertaken since the late 1960’s to improve accuracy and quality of the steel and outfit production work [5]. This has not been matched by an equivalent effort in coating activities/facilities. The objective of all this work was to bring processes under control to enable predictability of performance so that production systems can be better engineered to Standardise, specialise and simplify [6]. Dr Shinto re-enforced the importance of gaining control of production and the role of management systems to achieve process control in the work he undertook in the early 1960’s [7]. In this work Dr Shinto reviewed both steel and outfit work. However even at this time the challenges required to gain control of the Steel and Outfit work was so great that very little effort was applied to understanding coatings. However the groundwork was set for the first attempts to consider coatings in the form of the Hull Block Coating Method (HBCM) that was introduced at IHI at that time. As the steel and outfit work was better understood and brought under control, the importance of the management systems required to assure predictability was also highlighted and lead to the next big challenges in control of the shipbuilding process.

The inspection of many aspects of the coatings activity (surface cleanliness, finish of coating) are often subjective, rather than objective). This means that often the variation in expectations can add considerable unscheduled work for the yard (this situation is likely to be aggravated by the new IMO MSC.215 (82) performance standard for ballast tank coatings. There is a real need to better standardise the assessment in a readily measurable way and to ensure that the data to be recorded for the Coating Technical File required by the regulations also does not overburden the yard. 3. PROCESS IMPROVEMENT Shipbuilding process improvement has often shown that it is not the technology that is a barrier to improvement but the managerial processes and worker skills that are required to effect change, that are the most important elements. Managerial tools are needed to bring processes under control, to improve stability and most importantly in coating activities to increase predictability by reducing variation. Imbalance in the development of shipbuilding technology and management systems between, design, pre-production activities, steel, outfit and coating work lead to “islands of automation” [8] this results in inherently unstable and non-predictable processes, that are difficult to balance and hence difficult to control and schedule effectively and give poor quality output and hence increased costs. The importance of putting in place good management control systems to enable productivity improvements to be made with modest technology investments was comprehensively reviewed By Ohno and Sekiya [9] in 1990. However what has become clear over the last 20 years is that despite all the work undertaken to bring both management and production processes under control to improve productivity is that somehow the coating process and often the coating department has been left behind and the recent challenges raised by the environmental regulations and the end-user focus on coatings has highlighted these failings in many yards around the world. 4. RECENT DEVELOPMENTS In the last 17 years there have been no less than 20 pieces of regulation that have impacted in one form or another on how shipyards prepare steel and apply coatings. These have included:

TBT ban VOC management Ballast tank coatings



Ballast water treatment technology Worker exposure limits Etc.

There have also been IACS guidelines as well as concerns raised by accelerated corrosion and the uses of higher tensile steels on vessels of all types but in particular Bulk Carriers. This rate of change has tended to further de-stabilize the coating process at a time when the production tempo (TACT time) has been steadily improving to maintain competitiveness. It has also meant that yards have had to continually adapt their processes at both pre-production and production to meet the needs of the changing regulatory environment. Despite all these problems that have burdened the coating process in shipyards, over the last 10 years, There have been at least 4 major shipyard developments (in China, Korea, Europe and the USA) where inadequate consideration was given to the need to integrate the coating process into the facilities and build strategy and indeed in two of the yards major investments in steel throughput was not matched with any investment in coating facilities to deal with the increased output, resulting in severe bottlenecks and poor return on investment in terms of improved throughput. Some shipyards have attempted to buy their way out of trouble by investment in new facilities, most notably paint cells or climate control. However this is an expensive route for yards to adopt as coating facilities are not cheap. Often the management systems have also simply failed to get the best out of the facilities or indeed, the facilities were poorly served as a result of lack of investment in infrastructure (such as transport/materials handling to support the facilities). 5. TECHNOLOGY DEVELOPMENT It is a fact that the description of the technology used in coatings given by Takezawa in 1972 is still a fairly accurate description of the coating processes today. So why is this the case? When in many other aspects of ship production technology from design to welding and from cable trays to the chemistry of the paints, technology has moved on considerably and has often left the processes of 40 years ago unrecognisable. It should therefore be no mystery to understand why the coating process is causing difficulties today. The penalties of the lack of control and stability in the coating process manifest themselves in quality, time and cost penalties [10].

In their paper [10] the authors reported a study of the leading US shipyards under the auspices of the National Shipbuilding Research Programme SP-3 Panel (Paint and Blast) and developed a benchmarking tool to enable them to compare best practice from Europe, Korea and America in both pre-production and production activities. The work highlighted the need for new technologies and better management tools to manage the coating process and bring it under control. However most importantly it identified the lack of integration or consideration of coating activities when other processes are being planned for both facility development and the physical production process. The work also highlighted the poor levels of understanding of other departments within the yard of the role of coatings and the increasingly high proportion of man-hours the coating process now absorbs out of the total shipbuilding man-hour budget. The time penalties in many yards are significant as time lost at the bottleneck is time lost at the whole facility. This has recently been demonstrated during the discussions revolving around the introduction this year of the IMO Resolution MSC.215 (82), or the Performance standard for protective coatings for ballast tanks and double sided skin spaces. The yards were very quick to realise the implications of the increased demand placed on them by this regulation, while owners were rightly concerned about the through life performance of their assets. The cost penalties are not insignificant, apart from the investment in facilities the cost of re-work has at times come very close to bankrupting some yards. In recent years a number of yards (from around the world) have suffered huge cost over-runs resulting from poor control of the coating processes and the problems are being evidenced by increasing number of claims being settled both within the public eye and in private. 6. SOURCES OF INADEQUACY The current status of the coating process within shipyards is unsatisfactory. The coating processes need to be made more predictable and brought under better control. They also need to be properly integrated into the production strategy and the levels of re-work in the form of touch-up, burn damage etc. reduced to levels that are more in line with those achieved in steel and outfit work. To suggest improvements, the nature of the failures/inadequacies must first be understood. The author has been fortunate to be involved with many shipyard projects related to the evaluation of the performance of coating activities. As a result of this work over the last 17 years the author has been able to



categories the inadequacies under the following headings:

Design Ship design Facility design

Coating selection Coating production technology

Surface preparation Application

Management systems Quality Training and education Inspection Environmental Health and safety Planning/Scheduling Etc.

Human issues The focus of any improvement activity must be based on Quality (to minimise re-work and improve ease of production), Cost (man-hours) and Delivery (time). In terms of quality this has to be reflected in both design and production, man-hours can only be controlled through good management systems and stable processes. While delivery in terms of coating activities is about productivity improvement, planning and scheduling and this is normally dictated by factors such as:

Drying time Access time Over-coating intervals Transport time Re-work time

These three elements Q (quality), C (cost) and D (delivery) must be applied to all aspects of the inadequacies that arise so as to improve the performance of the coating activities in total and leave them in balance (no island of automation) with each other and with steel and outfit work. It is also therefore important to standardise the processes, simplify the work and enable productivity increase through specialisation. The challenge therefore is to:

- Identify the sources of the inadequacies - Prioritise the benefits that can be gained by their

management and subsequent elimination. - Put in place the tools/culture to enable the

inadequacies to be reduced over time. The achieving of cultural change is the greatest barrier to productivity improvement and as how this can best be achieved is different from one company to the other, the remainder of this paper will focus on the technical

elements/tools and emerging technologies that a shipyard can use to help meet the challenges posed by the coating activities. This however should not in any way indicate that a shipyard could achieve benefits of change without cultural change. As Ohno and Sekiya [11] declared: It is first necessary to create a sense of trust among all members of an organisation, from top to bottom. By this there will emerge “open communication” between the management and workers. Thus both will often have “common sharing of the objective” and “general knowing of the results”. It is also necessary that the managers and workers have informal meetings on some occasions… Thus it is very important to create the right cultural environment to enable the challenges posed by the coating process to be tackled successfully. 7. IMPROVEMENTS The experience of the author indicates that the critical factor to the longevity of the applied coating through life is its application during new build. The better the quality of the initial application, the longer the life of the coating in service. There are still occasionally problems with the paints themselves but often premature failure is caused by inadequacies in the coating process itself. Taking each of the sources of inadequacy in turn, some possible solutions/techniques are proposed and some suggestions made as to how yards should modify their current practices to meet the future challenges. Of course in shipbuilding the first challenge posed for coatings is that of material selection. The use of mild steels in one form or another for the hull structure and many other aspects of the vessel, and the placing of the vessel in an electrolyte (seawater) will lead to corrosion unless a barrier can be created between the Air, Metal, Cathode, Electrolyte (ACME). The current chosen form of this barrier is a coating applied in a liquid form and allowed to cure. 7.1 DESIGN Design has to be broken into two elements, the design of the ship itself and the design of the shipyard facilities for coating work 7.1.1 Ship Design Designers have long been accustomed to designing ships to meet the operational criteria and also to allow ease of production and outfit installation. However, little or no attention has been paid to design for corrosion prevention.



In fact the tendency is to design in corrosion problems by:

Creating complex geometries that are difficult to prepare and coat and result in many edges that can corrode. Creating tight spaces that are difficult to access and to ventilate/de-humidify Creating tight spaces that cannot be easily coated using an airless spray gun but require build up coats to be applied by brush and roller. Creating spaces that are subsequently difficult to repair and maintain Having flat surfaces with no camber, tumble-home or rise of floor to assist with drainage Making use of dissimilar metals Poorly designing outfit items for installation, resulting in corrosion traps.

To overcome some of these problems the author suggests some possible solutions that may be considered at the design stage:

Conduct a shadow analysis of the compartment. This can be undertaken by a Computer Aided Design system (CAD). It would provide a measure of the difficulty to coat a compartment. If the CAD system can be used to provide the basic view a worker would see before he starts work on a surface then a flat surface (external hull) would have a shadow area of 0%, as the worker can see the complete surface. As the surface becomes more complex then the percentage of shadow areas (those the worker cannot see from his work position) increases, making the work harder. The aim of the designer therefore is to try and design spaces to reduce shadow areas. This will tend to result in alternative structural configurations such as corrugated sandwich panels [12] using laser welding. These structures have shown how complex internal spaces could be built using structural configurations that could offer 0% shadow. Conduct an edge analysis as for shadow analysis by CAD. Stripe coating of edges is a very time consuming, labour intensive and hence costly exercise. Despite the availability of edge retentive coatings there is inadequate confidence to eliminate these from critical areas [13]. This is a key area for designers to consider and again could be helped by alternative structural configurations.

A material analysis should be conducted to see which elements of the design can be replaced by

materials that offer greater resistance to corrosion, whether that is in the form of alternative steels or alternative materials for non-structural elements. For example increasing use of composite pipes and other fittings. Access analysis could also be made to ensure that the area to be coated can be worked on with minimum access requirements and provide good ventilation routes as well as ingress and egress for workers and equipment.

Total area coating analysis earlier in the design phase would allow better planning and scheduling activities. Some CAD systems have this capability but often there is a degree of inaccuracy or it provides only limited information.

Structural detail of individual components should be reviewed to make them easier to prepare and coat and hence aid longevity of coating through life.

7.1.2 Facility Design Facility design for coatings often has less engineering thought and effort put into it than that which is applied to other steel and outfit facilities. Faced with the current levels of variability in the production process there is a need for flexibility in how the facilities can be used to allow for the variation. Yet all too often the layout or design of the facilities create bottleneck themselves for example by only having one route in and out or by providing zero capacity to deal with the known variation in the process. As build times have steadily reduced, then the degree of surface preparation has been reduced in some yards, as the shop primer has been able to afford adequate weathering capability.

As vessel size/block size has steadily increased, many paint workshops have become too small to be efficient in their use. Using single workshops for both preparation and coating also creates problems in terms of efficiency, cleaning and maintenance as well as good schedule control.

There is therefore a need for a more engineering based approach to the design and layout of coating facilities based around the present and future production technology. 7.2 COATING SELECTION Paint selection methods have not changed for many years. Yards create a makers list and develop a standard generic specification to try and fix on a standard approach. However, there is a considerable reliance on the paint



supplier to create the contract specific specification (often with some consultation with the ship owner). This approach creates considerable problems for the shipyard. In general terms the shipyard scheme may state that for the ballast tanks the coating must be in line with the new IMO regulations and would be a multi-coat scheme of 320μ nominal Dry Film Thickness (DFT), plus two stripe coats. This is then issued to the paint suppliers to bid against. The paint supplier has now been provided with a target answer that must be met, and hence can now only compete on price. Instead the shipyard should consider the important functional aspects of paint selection for each area or each task it will perform. For example in ballast tanks, drying time to gain access for the second coat is very important, so one of the functional requirements should be drying time at the appropriate DFT. Each vessel area should be reviewed in a similar manner and the key functional attributes required of the coating identified. In addition the criticality of the area to enable the yard to meet schedule can be further assessed so that the importance of each attribute can be determined. Undertaking a paint specification assessment in this manner often provides very different results to the generic scheme approach and also offers real opportunities to integrate the coating scheme into the requirements of the build programme. In the experience of the author, this fundamental change in approach can save yards in the region of 10-15% of total coating costs during new build. It also allows consideration of the ideal time for scheme breaks and an assessment of coating progression on a compartment-by-compartment basis to maximise integration, improve quality and delivery time and hence reduce costs. For many years the selection of shop primer has been the choice of the shipyard. This has allowed the yard to standardise its processes. There is evidence of the potential for think about standardising on other products. The emergence of the “universal primer” offers the potential for yards to select the best-fit anti-corrosive and use that exclusively on all contracts and hence move the selection for this away from the owner. A yard has much to gain from the selection of the right functional specification for a universal primer to enable integration with the production process. 7.3 COATING PRODUCTION TECHNOLOGY The development of tools for surface preparation and application processes has lagged behind the rate of development of many other production technologies used

in shipyards. The process of coating is still recognisable to any one who worked in a shipyard 20 - 30 years ago. This results from a lack of really large companies involved in the marine coating tool development business sector, as it is a relatively small sector when compared to the needs of other industries. Thus developments in surface preparation methods and techniques as well as application methods have lagged as a result of inadequate investment. The use of this older technology in the increasing regulatory environment leads to waste, emissions, H&S issues that compound the fairly static productivity rates that have been achieved over that period of time, against a background of increasing areas to be coated (double hulls). There is a real need to improve the technology associated with surface preparation and application to reduce labour costs, improve quality and reduce the time of work. In addition there is a need to also improve inspection technology by using colour attributes in coatings [14,15]. These technologies are slowly emerging but do offer savings and better access for inspection. 7.4 MANAGEMENT SYTEMS Many studies carried out over the years have reinforced the basic finding of Deming [16] that management systems can account for up to 85% of all quality related problems. The coating process is no different. There are a number of key processes that need to be properly managed ensure proper integration of the coating process into the production process, these are:

Quality Training and education Inspection Environmental Planning/Scheduling

This is not an exhaustive list, but in the opinion of the author the items that are currently critical to the effective improvement of the coating process.

Quality in the form of minimising the man-hours used on re-work in the form of touch up and repair is critical. Many yards still find considerable interference between the coating process and the remainder of the production processes that often results in damage to the coatings. The cost of repair has been assessed and can be up to 14 times more costly than the initial application [17]. Thus it is very important for a yard to have a clear coating strategy that is properly integrated into the build strategy for the vessel. Training and education is critically important, not just to improve the capability of the paint department but to raise awareness in other departments and



trades of the limitations and capabilities of the coating process. Inspection problems have been reviewed earlier, however there is clearly emerging a need for not only more objective systems of inspection, but also better data management of the records obtained for future reference by the vessel through it service life. The target life of 15 years being set for ballast tank coatings will tend to increase the inspection burden on the yard and this will result in further schedule and quality disruptions. It is important therefore that inspection systems are reviewed. It is likely that there will be an increased pressure on inspection and audit that will add an extra burden on the coating department. The obvious route to improving this process is to consider the use of computer-based tools for the collection of data records [18]. The physical process of inspection could be greatly assisted by improved designs with fewer shadow areas and reduced complex geometry as well as access. Regulatory environment is constantly changing and yard personnel must be up to date with the regulations and assess the likely implications to the coating strategy, rather than try to make the existing procedures fit the regulations, they should be optimised/reviewed to take into account the new regulations and seek opportunities for competitive advantage. Environmental challenges are on the increase in terms of emissions, overspray, and waste management. All these factors have added a burden to the paint process and have tended to be reviewed in a piecemeal manner rather than carefully considered within the coating strategy of the yard. Planning and scheduling have been reviewed and the need for more predictability identified. For the present the need to consider the build strategy and the needs of the coating process are paramount to attain integration. However over time the key element will be to reduce variation and achieve higher degrees of predictability by a combination of improved, technology, systems and understanding.

7.5 Human issues Human issues are critical, coating work is perhaps the most dirty, the most dangerous and relatively poorly paid, thus ensuring workers are well motivated is important to the success of the required changes and developments. Without the people the problems will persist. There is no real evidence of automation being applied extensively in painting as there has been in welding and so the challenge of managing these personnel has to be considered carefully.

8. CONCLUSIONS It has been shown that the coating process has not developed in step with other activities in a shipyard. As a result it has become the bottleneck and created an imbalance in the production process. This problem is aggravated by the fact the process experiences considerable variation. To date a proper engineering approach to resolving these problems has always taken second place to steel and outfit technology and developments. However, this situation can no longer be sustained. The MSC.215 (82) marks a potential shift in the relative importance of the coating process at new building and what has been applied to ballast tanks, is likely to be applied to other critical areas. Shipyards must rise to the challenge and do so in a structured and methodical way, this means looking at all aspects of the process, from design, production, product selection, management and cultural issues. If these challenges are not met head on, then the increased burden on the bottleneck, will limit the throughput of the yard reducing competitiveness. Solutions have been proposed, some may readily be adopted while others may require some effort to put into place and gain acceptance. What is clear however is that there is much unused technology available to improve the performance of the coating process, the application must follow. 9. REFERENCES

1. Dr K Terai, T Kurioka, Future Shipbuilding Methods, Shipbuilders Association of Japan 20th anniversary commemorative prize essay, August 1969.

2. I Takezawa, Development of the automated shipyard, Paper presented to the Royal Society discussion meeting, January 1972

3. M Hargroves, J Teasdale, R Vaughan, The strategic development of ship production technology, TRINA 1975.

4. Kattan R, Townsin R, Baldwin L. Painting and Ship Production – Interference or Integration, RINA Conference on Corrosion, 1994

5. Kihara H, Yamamoto N, Recent Developments in Management and Production Methods in Japanese Shipyards, SNAME Diamond Jubilee meeting New York, June 1968.

6. Ichinose Y, Improving Shipyard Production with Standard Components and Modules, TSNAME, April 1978.

7. Shinto H, The progress of production techniques in Japanese Shipbuilding, University of Michigan Short Course, October 1980.



8. Bellonzi R, Islands of Automation in Shipbuilding, Journal of Ship Production, Vol 2, No 1 February 1986.

9. Ohno I, Sekiya O, Improving Productivity in a Japanese Shipyard, TRNECIES, May 1990.

10. Kattan, R, Blakey J, Panosky M, DeVinney S, Time and cost effects of the coating process, Journal of Ship Production, Vol 19, No.4 November 2003.

11. Ohno I, Sekiya O, Discussion to Improving Productivity in a Japanese Shipyard, TRNECIES, May 1990.

12. Roland F and Metschkow B, Laser welded sandwich panels for shipbuilding and structural steel engineering, Marine Technology II, Transaction of the Built Environment, Edited by Brebbia C, 1997

13. IMO, MSC.215(82) Performance standard for protective coatings for dedicated seawater ballast tanks in all types of ships and double-sided skin spaces of bulk carriers, December 2006.

14. Nippon Paint Co Ltd, NOA Coating Press release, October 2000.

15. Buckhurst M, Seeing things in a different light, Maritime Reporter pp 28, February 2005

16. Deming W E, Quality productivity and competitive position, MIT Press, 1982

17. Baldwin L, A Techno-economic assessment of new coating application for new-building marine production. PhD Thesis, Newcastle University, 1995

18. Speed L, WP6 Coating management system, Environmentally friendly coatings for shipbuilding and ship operations, European ECODock project, www.ecodock.net

10. AUTHORS’ BIOGRAPHY Dr. Raouf Kattan is the Managing Director of Safinah Ltd. a company specialising on the management of coating activities from raw material supply through to end of life use. He started his career in the merchant marine as a deckhand and has through his career focussed on ship-production issues. Since 1991 his main area of interest and research has been marine coatings.



SI technology and its Unique paint property

Nobuhiro Sasaki (Author) Nippon Paint Marine Coatings, Japan

Masana Takayama (Presenter) Nippon Paint Marine Coatings, Japan

SUMMARY

New technology of SI enables painter to control coating thickness during application, thereby uniform

coating with minimum DFT and minimal excessive coating is secured. Due to Self-Indicating / Inspecting

function, coating thickness applied can be judged by naked eyes without spot physical thickness measurement. This SI

technology will contribute to materialize and fulfill requirements of IMO-PSPC, and will be coating system for 21st

century. It is time saving and cost saving coating system, and gives benefits and merits for shipyard & shipowner.

We propose to disseminate this coating system to marine paint industry in view of substantially increasing

demands of coatings especially for water ballast spaces.

NOMENCLATURE

SI Self-Indicating or Self-Inspecting

PTM Physical Thickness Measurement

D&S Dots-and-Spots

S&A Sheet-and-Area

NB Newbuilding

M&R Maintenance & Repair

1. INTRODUCTION

Have you ever heard any paint which shows thickness by

color and a painter can control coating thickness in the

process of color changes ?

2. WHAT IS SI PAINT ?

2.1 PREFACE

2.2 EFFICIENCY OF SI BY PICTURE REPORT

2.3 EFFICIENCY OF SI AND ITS FUNDAMENTAL

PROPERTY

2.4 PRODUCTS INCORPORATED WITH SI

PROPERTY

2.5 CONCLUSION AND OUR PROPOSAL

2.1 PREFACE

The most important mission imposed upon marine paint

suppliers is to protect vessels, one of social assets, from

corrosion during ship’s life at sea.

The corrosion protection during ship’s service life is

easier said than done under severe environment the

vessels are exposed to.

Two pack epoxy paint complies to this requirement with

pretty good coating performance endorsed by laboratory

testing and becomes the mainstay coating for long life

corrosion protection.

Having said this, long life corrosion protection of vessels

at sea is not yet fully achieved with epoxy coatings and

does not live up to the expectation of ship owners.

Take water ballast spaces, for example.

Partial corrosion is inevitable in several years even

painted with utmost care on properly treated coating

surfaces.

Why the coating gets rusted on the water ballast tanks of

vessels when the coating is proved perfect and rust-free

on test panels painted & tested in the laboratory?

The difference or gap comes mostly from low paint

thickness, or low coating build, due to enormous painting

areas and difficulty of proper painting on complicate

critical parts of tanks.

Uniform coating of 250 microns on test panel does not

represent all painted surfaces of the vessel. Parts painted



below 100 microns will be rusted in an early stage after

painting.

SI (Self-Indicating or Self-Inspecting) paint is an answer

to solve such deficiency in painting. SI function enables

to make coating of paint panel represent the coatings

applied to water ballast spaces of vessels, or in other

words, the gap between test panel coating and working

horse coating on actual vessels is minimized by SI

property.

We herein introduce the concept of this new coating

system with picture reports of our reference list.


Look into the Picture 1and 2.

This shows coating condition of water ballast tanks 31

months after SI paint (NOA) was applied.

No corrosion noticed on all parts inclusive of critical

areas, plate edges etc.

Perfect condition.

The good result is achieved by proper application of

self-inspecting paint thereby the painted thickness is self

indicated and self inspected by painter. Painter can

judge painted thickness by his naked eyes during

spraying.

He is able to realize “when to stop spraying” and can

secure minimum thickness and avoid excessive thick

coating.

The coating on all water ballast tanks is done in the same

manner or as near to that of test panel with “uniform

coating”.

Picture 1 “EAGLE TOLEDO”(Tanker)

SI paint 1 coat X 250µm

WBT condition after 31months

inspected in Oct 2005

* No corrosion on plate edges, corners and

pieces…

Picture 2 ANSAC LEGACY ( Bulk Carrier )

SI paint 1 coat X 250µm

WBT condition after 42months

inspected in July 2007

* No corrosion on plate edges, corners and

pieces…


On top of surface preparation coating thickness (DFT) is

very important for long life corrosion protection.



S I Paint Non - S I Paints300 um < 500 ~ 800 um

300 um <

300 um <

300 ~ 400 um

80 um

150 um

230 um

20 ~ 50 um 20 ~ 50 umNon - S I Paints

200 ~ 250 um

70 ~ 100 um

500 ~ 800 um

Non - S I Paints

70 ~ 100 um

200 ~ 250 um

300 ~ 400 um

Colour Shows Thickness ! Thickness Shows Colour !

Thickness differencebut, No colour difference

This area measures 11 times thicker Than general paint !! Still, See-through texture with 230 microns !!!

Physical thickness measurement (PTM) on wet/dry

coating is carried out for ensuring paint thickness. The

PTM is to check coating thickness on dots-and-spots

(D&S) basis and not in sheet-and-area (S&A) basis.

The D&S measurement does not represent coating

thickness on vast surrounding plate areas.

SI technology enables painter to judge coating thickness

on “S&A basis” (not “on D&S basis”) during painting

without using thickness gauge.

SI paint is developed and launched in the marine paint

market (NB and M&R) based on opacity / pigmentation /

dispersion control technology.

Painter himself can realize when to stop painting during

spraying in the process of wet color change.

This will substantially reduce painting and inspection

workload and make painting job simple and easy.

2.3 EFFICIENCY OF SI AND ITS FUNDAMENTAL

PROPERTY

On top of surface preparation coating thickness (DFT) is

very important for long life corrosion protection.

Physical thickness measurement (PTM) on wet/dry

coating is carried out for ensuring paint thickness. The

PTM is to check coating thickness on dots-and-spots

(D&S) basis and not in sheet-and-area (S&A) basis.

The D&S measurement does not represent coating

thickness on vast surrounding plate areas.

SI technology enables painter to judge coating thickness

on “S&A basis” (not “on D&S basis”) during painting

without using thickness gauge.

SI paint is developed and launched in the marine paint

market (NB and M&R) based on opacity / pigmentation /

dispersion control technology.

Painter himself can realize when to stop painting during

spraying in the process of wet color change.

This will substantially reduce painting and inspection

workload and make painting job simple and easy.

Look into Picture 3.

3 panels show how SI paint looks like in comparison with

non-SI paint.

Far left panel was applied with SI paint, and the rest 2

panels were applied with non-SI paint.

There are 3 areas which do not reach the specified DFT

(300 microns) in each panel, but the areas of 2 panels

painted with non-SI version do not show the color

difference. Color looks the same irrespective of different

thickness. 70 microns or 300 microns ? (e.g.) We cannot

see.

As is non-SI panels, very low DFT areas exist in vast and

complicated surfaces of vessels, and such areas will be

corroded with the lapse of time.

On the other hand, lower DFT areas in SI paint can be

visually judged and such designated areas are touched-up

during or after application before stagings are taken off.

This reduces overall painting and inspection workload,

especially in case of water ballast tank coating.

Picture 3 Panel of SI paint and non-SI paint

2.4 PRODUCTS INCORPORATED WITH SI

PROPERTY

By making best use of SI technology,

we have product line-up for ;

Newbuilding

NOA 10 F for outside hull & all exterior areas



NOA 60 HS for water ballast tanks / other tanks.

Maintenance & Repair

NOA 10 M for outside hull & all exterior areas

2.5 CONCLUSION AND OUR PROPOSAL

SI paints explained as above are recommended to

positively comply with new IMO coating requirements.

It is time saving and cost saving coating system, and

gives benefits and merits for shipyard & shipowner.

Ultimate mission and objective of marine paint makers is

to provide vessels with quality coatings to live up to IMO

requirements of long life (over 15 years) corrosion

protection in water ballast spaces.

The integral quality of coatings will be achieved only

when paints are properly coated with uniformity of

specified thickness on all parts of painted surface.

Marine paint makers, so far, have not succeeded in

supplying paint to users which provides painters with

self-inspecting function to control coating thickness

during paint application. Therefore, coating thickness

must be checked / inspected by physical thickness gauge

after painting.

This PTM (Physical Thickness Measurement) is nothing

but a mean / measure / step to confirm paint thickness.

IMO new coating regulation demands hefty PTM

inspection.

This will cause big cost increase during new construction.

The cost of such inspection is a very “negative cost”.

We, Nippon Paint Marine Coatings, propose the visual

self-inspecting paint instead of conventional type which

needs PTM on D&S (dots & spots) basis.

Which do you think is the better coating system, PTM

type or SI version ?

We strongly recommend SI system for the coating of 21st

century.

We strongly recommend to save the “negative cost” for

inspection and to invest “positive cost” for research and

development of genuine quality products for the ultimate

long life corrosion protection of vessels.

3. AUTHOR’S BIOGRAPHY

Nobuhiro Sasaki holds the current position of technical

director at Nippon Paint Marine Coatings Co., Ltd.

Responsible for research & development of marine

paints.



CORROSION PROTECTION REGULATIONS TO IMPROVE SHIP’S SAFETY? Thorsten Lohmann, Germanischer Lloyd AG, Germany Daniel Engel, Germanischer Lloyd AG, Germany SUMMARY The International Maritime Organization sets new standards in the corrosion prevention of seawater ballast tanks on steel ships. With the adoption of an international valid coating standard a uniform quality shall be achieved to raise ship’s safety. This means at the same time that new requirements come into force with partly huge impact on the shipbuilding industry. 1. INTRODUCTION From a corrosion point of view, seawater ballast tanks on steel ships are one of the most critical areas. Hence the following article deals mainly with the corrosion protection in these tanks. Specific corrosion problems and protections through coatings will be discussed with reference to a newly released, internationally valid standard for the corrosion protection of seawater ballast tanks on steel ships. With the constant contact to seawater, different levels of filling and possibly extreme varying temperatures, a proper corrosion protection in these tanks is essential. With a damaged or improper corrosion protection in ballast water tanks severe corrosion rates are possible. These can, if not detected in time, lead to immense damages with devastating consequences for the construction and therewith possibly for humans and the environment. Unprotected ship steel shows considerable rates of corrosion in seawater. In average, rust-off rates of 0.4 to 0.8 mm per year have been observed, unprotected steel in water ballast tanks of ships showed partly up to 3 mm per year. The corrosion rates in these tanks are subject to considerable fluctuations and can rarely be determined in a precise way. Operational area of the vessel, frequency of water changes, the corrosion protection system and its condition, the character of tank design and especially the composition of the ballast water are key factors. With the knowledge of the occurrence of corrosion in these tanks corrosion factors are added to the calculated steel thicknesses. In addition, an effective corrosion protection system is to be applied in ballast water tanks usually by a hard coating system, sometimes in combination with sacrificial anodes. 2. NORMALLY USED PROTECTION SYSTEMS IN SEAWATER BALLAST TANKS ON STEEL SHIPS Typical paint systems for ballast water tanks are epoxy based systems with a nominal dry film thickness of around 300 µm. The main coating is most commonly applied in two layers. One of the key issues for a resistant coating system is the surface preparation which consists of the surface profile and the surface cleanliness. Furthermore special attention has to be paid to the preparation of the welding seams and the edges of profiles and stiffeners.

The steel plates and profiles to be used for the ship’s hull and therewith in the ballast water tanks are normally blasted to a surface cleanliness of Sa 2 ½ acc. to ISO 8501-1 with a defined roughness profile. To protect the surface during the following building period an overweldable shop primer is applied on the steel surface afterwards. Depending on the compatibility with the main coating system it is not unusual that the shop primer partly remains on the surface and therewith forms the underground layer of the following main coating system. Further critical factors for a good surface preparation are the salt and dust level on the surface. Especially the salt level is often intensified with most shipyards lying close to the sea. With a too high salt level the risk of blistering and loss of adhesion of the coating system is given. The same problem of loss of adhesion might occur with too much dust on the surface whereas with dust, the amount and the size have to be observed. The salt and dust limits for a coating system are specified by the paint manufacturer in the relevant coating specification. Another critical area within the coating process of ballast water tanks on ships is the surface preparation of profile edges and welding seams. Sharp edges have to be grinded to give the possibility of reaching the specified dry film thickness.

Figure 1: Stripe Coat

The same applies to welding seams which often have to be smoothened if not welded automatically. Weld spatters have to be removed to ensure smooth and even surfaces for the paint application. Edges and welding seams not only have to be smoothened but it is essential to apply a stripe coat by brush or roller (usually one or two stripe coats are necessary) to ensure the achieving of the nominal dry film thickness (see pictures). The full coat is then applied by spraying. In some water ballast tanks in addition to the coating system, which forms the passive barrier against corrosion, an active corrosion protection system by sacrificial anodes is installed. The anodes are a supplementary



protection if installed in a proper way. This means that they have to be evenly distributed in the tank to avoid shadow effects and to have an overlap of the ranges of the anodes. It is also very important to ensure a permanent electrical connection. Special attention has to be paid to the fact that sacrificial anodes only work when they are submerged in the electrolyte (seawater), which might not permanently be achieved in a ballast water tank. Further it has to be proven that the coating system is compatible with a cathodic protection system. 3. CORROSION PROTECTION RULES AND REGULATORY BODIES 3.1 CLASSIFICATION SOCIETIES In the shipping industry, classification societies are non-governmental organisations that promote the safety and protection of the environment of ships and offshore structures. This is achieved by setting technical rules, confirming that designs and calculations meet these rules, surveying ships and structures during the process of construction and commissioning, and periodically surveying vessels to ensure that they continue to meet these rules. Classification societies employ or comprise of naval architects, engine specialists, material and welding specialists, electrical engineers, etc. and are usually located at ports around the world. The ships are accompanied and surveyed during the new building process and periodically during their entire lifetime. Marine vessels and structures are classified according to the soundness of their structure and design for the purpose of the vessel. The classification rules are designed to ensure an acceptable degree of stability, safety, environmental impact, etc. In particular, classification societies may be authorised to inspect ships and other structures and issue certificates on behalf of the state under which flag the ships are registered. Concerning the seawater ballast tanks the classification societies are publishing rules requiring not only routine inspection of these tanks but also a corrosion protection system in order to avert the risk of an unprotected or not sufficiently protected seawater ballast tank. Thus, the International Association of Classification Societies (IACS), an association of the leading classification societies of ships, elaborates so called ‚Unified Requirements’ (binding standards for all members), which define certain minimum requirements for seawater ballast tanks among other things concerning corrosion protection. These minimum requirements released by IACS state that the seawater ballast tanks are to be provided with an effective protective coating system. However there is no defined standard of how to achieve an effective protective coating system which means that there are no requirements concerning surface preparation, dry film thickness, qualification of the coating system for the range of application, application method or the like. The

interpretation and technical implementation of these minimum requirements is left to the associated IACS members, which determine – more or less precisely – the details of admissible methods via their rules and under consideration of other standards. The classification societies have extended these minimum IACS requirements by setting further demands concerning the corrosion protection of seawater ballast tanks. Germanischer Lloyd (GL) requires a corresponding corrosion protection in all seawater ballast tanks on every GL-classified ship – independently from dimension and ship type. This means that a product certification of coating systems applied in ballast water tanks is necessary, i.e. qualification tests have to be carried out by laboratories, independent from the coating manufacturer, in order to prove the performance of the product. After passing these tests successfully (normally following ISO 12944), the coating system will receive a type approval valid for seawater ballast tanks by Germanischer Lloyd. A list of every GL type approved seawater ballast tank coating is published in the Internet. Furthermore is in the current edition of Germanischer Lloyd Rules a minimum dry film thickness for the ballast water tank coating system of 250 µm required as well as an appropriate surface preparation. These requirements are part of the drawing approval, i.e. the coating specification for seawater ballast tanks has to be submitted to Germanischer Lloyd for examination and approval at an early state of construction and especially prior the starting of the coating work. Other classification societies require similar additions exceeding the minimum ‘Unified Requirements’ defined by IACS. The coating requirements will change in the future which is described under point 4. These measures of corrosion protection only determined by minimum requirements are very different concerning their quality. These differences shall now be harmonised on an international level. The measure representing the greatest scope of an international harmonised standard is the development of a coating performance standard by the International Maritime Organization (IMO), which shall be applied to the coating of seawater ballast tanks of ships above 500 GT and on the double skin spaces of bulk carriers longer than 150 m. 3.2 INTERNATIONAL MARITIME ORGANIZATION The International Maritime Organization (IMO) with its head office in London has been established in 1948 with the intention to improve the safety of ships by developing and adopting international regulations, which have to be observed by the Member States. Today the IMO consists of 167 Member States. IMO's first task was to adopt a new version of the International Convention for the Safety of Life at Sea (SOLAS), the most important of all treaties dealing with maritime safety. This was achieved in 1960 and adjusted in 1974. Further Conventions and Resolutions have followed and will follow with the permanent adjustment


http://en.wikipedia.org/wiki/Shipping

http://en.wikipedia.org/wiki/Non-governmental_organization

http://en.wikipedia.org/wiki/Non-governmental_organization

http://en.wikipedia.org/wiki/Structures

http://en.wikipedia.org/wiki/Ship

http://en.wikipedia.org/wiki/Electrical_engineer


of these conventions. Surely, the main focus of IMO is and will remain the ship’s safety, but there is a further task which needs international regimentation and conventions – the protection of our environment. IMO’s Convention for the Prevention of Pollution from Ships (MARPOL) is the most important regulation in this matter. IMO is divided in different committees and sub-committees; the committee responsible for ship’s safety is the ‘Maritime Safety Committee’ (MSC). In the scope of further development of the safety of tankers and bulkers, MSC decided in December 2002 that it is necessary to address the need to develop an international coating standard for seawater ballast tanks and void spaces in the double hull of these ships. IMO’s sub-committee ‘Ship Design and Equipment’ (DE) was charged with this task. The main reason for this decision lies in the required double hull construction of tankers and bulkers which have a greater surface exposed to possible corrosion problems. Further the inspection of these areas is much more difficult due to its construction. Moreover the reigning atmosphere in double hulls makes corrosion effects very probable, which may lead to a higher rate of corrosion. In June 2005, MSC decided – based on an already existing draft of an international coating performance standard for ballast water tanks and void spaces on tankers and bulkers – to extend the scope of this standard also to ballast water tanks of every ship type. As before, this duty was delegated to the sub-committee DE. At the beginning of December 2006, MSC finally adopted the designed coating standard for ballast water tanks (meanwhile void spaces are considered separately). The coating standard is settled in the IMO Resolution MSC.215(82). It will be made internationally mandatory by an amendment of the SOLAS Convention. 4. CONTENT OF IMO’S COATING STANDARD In detail IMO’s Performance Standard for Protective Coatings implies new requirements that, by far, exceed and render more precisely the above mentioned ‘Unified Requirements’ by IACS and even the classification societies’ standards. Today one can say that the adoption of this standard means extensive changes for shipyards, ship owners, coating manufacturers and classification societies. The aim of the coating standard is to achieve a coating lifetime of 15 years in the seawater ballast tanks. Up to now there is no regulation that specifies the intended lifetime of a coating in seawater ballast tanks. The intention is that the coating remains in good condition after 15 years. The future will show whether this target can be obtained following the new standard. The intention is that the lifetime shall be achieved by the definition of concrete requirements, limit values and control mechanisms during the construction phase. Accordingly, the coating standard indicates clearly

defined limit values for the surface preparation concerning cleanliness, surface profile, salt level, dust grade, dry film thickness, etc. Precepts are also given with respect to the selection of an appropriate coating system, application methods and required pre-qualification tests of coating systems. Naturally limit values and application requirements are already existent and come along with each coating system. However they are usually defined by the coating manufacturers with regard to specific characteristics of the coating systems and not by an international unified standard. Moreover verification and inspection methods concerning these requirements and limit values in practice are not regulated in a harmonised way nowadays and are fulfilled with a very varying diligence. Three main items shall specifically be amplified because they are completely newly introduced and representing at the same time major consequences for the shipbuilding industry. 4.1 PRE-QUALIFICATION AND CERTIFICATION OF THE COATING SYSTEM According to the IMO PSPC, coating systems have to be pre-qualified in a laboratory test prior to be used on board. The laboratory test is clearly described in the standard including the testing facility, the panels to be tested, the test duration and the acceptance criteria to be achieved after the testing period. The testing facility simulates the conditions in a seawater ballast tank including ship’s movement, adjacent heated tanks and different levels of filling. In the testing tank different panels, coated with the coating system to be tested, are positioned. One panel is assembled with a sacrificial anode whereas on other panels the coating is artificially hurt. The testing period in the tank is 180 days.

Figure 2: Wave tank for testing of ballast tank coatings

Further the coating on two test panels is tested in a condensation chamber also for 180 days. One more panel will be exposed to dry heat for 180 days to simulate boundary plating between a heated bunker tank and a ballast tank in the double bottom.



With successful testing results the coating will be certified by a type approval or statement of compliance issued by the administration or recognised organisation which is usually the classification society. The control of this certificate will be part of the coating inspection process. 4.2 COATING INSPECTORS Another big issue that comes along with the IMO Coating Standard is the implementation of verification, inspection and documentation items. Those items shall ensure that the defined limits concerning surface preparation, salt and dust limit, dry film thickness, etc. are achieved and obeyed. This means that new control persons in form of coating inspectors have to be included in the ship yard’s quality control system. Coating inspectors need a special qualification which has to be verified by the administration or recognised organisation. They inspect and document the complete coating process of the ballast water tanks. The inspection and documentation items of the coating inspectors are clearly defined in the standard. 4.3 COATING TECHNICAL FILE The documentation of each single step of the coating process will be filed in a Coating Technical File (CTF), the third major introduction of the IMO standard. The CTF will include, amongst others, the reports of the coating inspector, technical data sheets of the coating system, type approval certificates, procedures for in-service maintenance and repair of coating systems, etc. The CTF remains on board of the vessel and shall be maintained throughout the life of the vessel. This means that inspection and maintenance of the coating shall be continuously recorded including location and work specification. 5. IMPLEMENTATION PROCEDURE AND DATES The IMO PSPC will be made mandatory through an amendment of the SOLAS Convention (see point 3), settled in Resolution MSC.216(82) Page 3, and is therefore a statutory requirement. Basically all commercial vessels are built under the SOLAS Convention nowadays which means that with the amendment the coating standard will be made internationally mandatory. IMO has set three different dates to activate the new coating standard. It will apply to seawater ballast tanks of all types of ships of not less than 500 gross tonnage and double-side skin spaces arranged in bulk carriers of 150m in length and upwards

• for which the building contract is placed on or after 1 July 2008; or

• in the absence of a building contract, the keels of which are laid or which are at a similar stage of construction on or after 1 January 2009; or

• the delivery of which is on or after 1 July 2012.

An exception from the a.m. dates exists for tankers and bulkers built under the Common Structural Rules (CSR) released by IACS. For those types of vessels the coating standard is already mandatory from its date of adoption on which was 8 December 2006. This date applies to the contracting date of vessels. 6. CONCLUSIONS With the intent of the constant improvement of the ship’s safety the newly developed standard might be a good contribution from a corrosion protection point of view. With seawater ballast tanks being one of the most jeopardised areas on a steel ship and with devastating damages in these areas still appearing, it can been seen as a good approach to set international valid rules and technical requirements concerning the coating of these tanks. It is however to be awaited the issue how the technical requirements will be realised and if it is practicable to have one standard for ballast water tanks on different types of vessels. All involved parties (shipyards, owners, classification societies, coating manufacturers, application companies, etc.) will be faced with partly big changes.

Certainly Germanischer Lloyd will give all necessary support that is needed and will provide the class relevant inspection requirements that come with this standard.

It is already decided by IMO to develop and release further coating standards for steel ships. This includes regulations for the coating of void spaces on certain type of vessels, the coating of the cargo tanks on crude oil carriers and a maintenance standard for the seawater ballast tanks as a supplement to the described coating standard.

It is obvious that the ship’s safety can be improved by proper corrosion protection. It has however to be paid attention that the regulations are a good compromise between sufficient protection and economical efficiency. This ensures the acceptance of such regulations and therewith the optimum realisation. 7. AUTHORS’ BIOGRAPHIES Daniel Engel is the head of the Competence Centre Materials and Products and the Department Materials and Corrosion Protection at Germanischer Lloyd. Thorsten Lohmann is engineer in the Department Materials and Corrosion Protection at Germanischer Lloyd. He is responsible for the certification of coatings, corrosion protection measures and antifouling systems.



Class NK’s Course of Action to Protective Coating – Guidelines for Performance Standard for Protective Coating Contained in IMO Resolution MSC.215(82)

Toshitomo Matsui, Class NK

1. PREFACE

IACS Common Structural Rules (hereinafter referred to “CSR”) has been effected from 1st April, 2006, and applied to a ship of which the building contract is signed on and after that date. In the section of Corrosion Protection of CSR the followings are specified for sea water ballast tanks and the void double skin spaces of bulk carriers:

“For ships contracted for construction on or after the date of IMO adoption of the amended SOLAS regulation II-1/3-2, by which an IMO “performance standard for protective coatings for ballast tanks and void spaces” will be made mandatory, the coating of internal spaces subject to the amended SOLAS regulation are to satisfy the requirements of the IMO performance standard.

Consistent with IMO Resolution A.798(19) and IACS UI SC122, the selection of the coating system, including coating selection, specification, and inspection plan, are to be agreed between the shipbuilder, coating system supplier and the owner, in conjunction with the Society, prior to commencement of construction. The specification for the coating system for the spaces is to be documented and this documentation is to be verified by the Society and is to be in full compliance with the coating performance standard.

The shipbuilder is to demonstrate that the selected coating system with associated surface preparation and application methods is compatible with manufacturing processes and methods.

The shipbuilder is to demonstrate that the coating inspectors have proper qualification as required by the IMO standard.

The attending surveyor of the Society will not verify the application of the coatings but will review the reports of the coating inspectors to verify that the specified shipyard coating procedures have been followed.

It goes without saying that protective coatings are not just for ballast tanks, they are necessary for ease of maintenance and keeping ships in good condition.

CSR having maid Society’s surveyors not to verify the coatings’ application but to review the coating inspector’s reports, Class NK recognizes the important role of coating inspectors and therefore has decided to prepare the guidelines for them in order to clarify the methods and criterion of inspections, criteria for them.

On the other hands Class NK concerned much that there are too few coating inspectors qualified as “FROSIO Red” or NACE level 3” in this industry comparing to duly implement IMO PSPC to the rushing amount of new shipbuilding vessels.

2. GUIDELINES FOR COATING INSPECTION

2.1 For Guidelines

In order to maximize the effectiveness of protective coatings, it is especially important to improve the



quality of coating application. The IMO PSPC1 stipulates that the following be taken into account when developing a coating design and coating work plan:

It is essential that specifications, procedures and the various different steps in the coating application process (including, but not limited to, surface preparation) are strictly applied by the shipbuilder in order to prevent premature decay and/or deterioration of the coating system. (IMO PSPC 3.3.1)

The coating performance can be improved by adopting measures at the ship design stage such as reducing scallops, using rolled profiles, avoiding complex geometric configurations and ensuring that the structural configuration permits easy access for tools and to facilitate cleaning, drainage and drying of the space to be coated. (IMO PSPC 3.3.2)

Inspections by the coating inspector during the application process are crucial in order to ensure conformance to IMO PSPC, or in other words, to ensure that the basic requirements stipulated in IMO PSPC are being followed adequately.

Class NK believes that coating inspectors need to share a common understanding of what (level of quality) is deemed acceptable in regards to protective coating for any vessel. Therefore, Class NK put together the “Guidelines for the Performance Standard for Protective Coatings” from the sources below, as a guide for shipyards and coating inspectors regarding coating inspections in accordance with IMO PSPC.

“Guidelines for Coating Inspection on PSPC,” prepared by the Japan Ship Technology Research Association (hereinafter referred to “JSTRA”) to provide guidance for coating inspection carried out by shipyards and coating inspectors in regards to Japanese and international standards, is included in the ANNEX of these guidelines for your reference. An official response is yet to come from IACS regarding the questions from Japanese industry, but any new developments will be incorporated into these guidelines promptly.

IACS established the IACS-Industry Joint Working Group on Coating (JWG/COATING) to address the problems that arise in regards to the application of IMO PSPC. These guidelines will be updated regularly with interpretations from the IACS Common Interpretation and Q&A developed by JWG/COATING to ensure that the latest information is available.

Hoping that “Guidelines for Performance Standard for Protective Coatings contained in IMO Resolution MSC.215(82) (draft)” will be of good use to you.

Generally speaking there are very many negotiations between a ship owner and a ship builder before signing a building contract. In this contract it is one of the obligations to comply with IMOPSPC. However, there seldom happens for a ship owner and a ship builder to negotiate the details of coating inspections.

1 IMO Resolution MSC.215(82) (adopted on 8 December 2006 at MSC82）Performance Standard for Protective

Coatings for Dedicated Seawater Ballast Tanks in All Types of Ships and Double-Side Skin Spaces of Bulk Carriers



Classification societies are usually not involved in the negotiations at this moment.

As like class rules specifies the details of the scantlings of construction and welding, Class NK realize the necessity to give both ship owners and ship builders the guidelines of coatings for the duly compliance with IMO PSPC as one of the conditions for class registration.

Needless to say, the coating inspectors play the important role to apply IMO PSPC to a ship during construction in order to assure her coating works to be complied with the requirements of IMO PSPC.

As CSR specifies, class surveyors will only review the report of coating inspector to verify that the specified shipyard coating procedures have been followed.

In other words coating inspectors shall share with the allowable standards of coating work performances and also the unified understanding of quality of coating works. Class NK has worked from the scratch for preparing the “Guidelines for Performance Standard for Protective Coatings contained in IMO Resolution MSC.215(82)” (hereinafter “Class NK Guidelines”) for coating inspectors.

2.2 JSTRA’s “GUIDELINE FOR COATING INSPECTION ON PSPC”

The working group for PSPC has been set out by JSTRA for duly implementation of IMO PSPC. The members of this working group are from shipyards, manufacturers, ship owners, institutes and class society.

Under the above working group two sub-working groups were also set. One is for the approval test and certification of coating system and the other one is for drafting guidelines for coating inspectors. ClassNK chaired the sub-working group for guidelines for coating inspectors and also took part in the other sub-working group.

The sub-working group for guidelines extensively worked to draft the “GUIDELINE FOR COATING INSPECTION ON PSPC” (hereinafter referred to JSTRA Guideline) around year end of 2006.

JSTRA Guideline has been developed on the principles of coating inspection as follows:-

The objective of the coating inspection is to ensure that the required minimum level and quality of protective coatings by PSPC is adequately applied.

Coating inspector should understand that perfect execution of coating application and inspection, throughout the entire surface without any small imperfectness is hardly achievable and all inspectors should have unified understanding as to what extent is acceptable as the required minimum level and quality of the protective coatings for any ship built in any shipyard.

For example, the check points for DFT measurements for the judgment of 90/10 rule are clearly indicated in the annex 3 of PSPC, but this cannot guarantee that 90/10 rule is perfectly achieved for the entire surface. The common understanding is that such sampling methods is practically enough for making the judgment, and if the sample measurements do not satisfy the criteria, additional spot checks should be taken for any area considered necessary by the coating inspector.



Unless expressly provided otherwise in PSPC and this Guideline, inspection by sampling and statistical method should be adopted to the extent necessary for making practical judgment. This means that the extent of inspection depends on the quality control of shipyards and should be allowed to vary better shipyards to ensure that the required minimum level and quality is achieved.

The sub-working group drafted the JSTRA Guidelines taking into consideration that it will be not only domestic but also global guidelines. Its final draft was proposed to IACS by Shipbuilding Association of Japan with the cooperation (SAJ) of Korean Shipbuilders Association (KOSHIPA), and IACS Joint Working Group/Coating used it as one of the key materials for ”GUIDELINE FOR IMPLEMENTATION OF MSC.215(82) PERFORMANCE STANDARD OF PROTECTIVE COATINGS” (hereinafter referred to IACS Guidelines) in its meeting at Pusan, Korea in May, 2007.

IACS has established its internal expert group and joint working group with industries concerned to develop practical approaches to implement IMO PSPC, and the meeting were held in last May and August. The IACS common understandings being developed by the working groups will be timely incorporated into Class NK Guidelines.

3. COATING INSPECTION

As for coating inspection, a superintendent with a shipyard inspector daily inspect the surface preparation such as edge preparation, blasting, salt content check, dust, and coating application such as coating, drying, recoating, dry film thickness measurement.

IMO PSPC requires those inspections, such as work log and measurements to be documented and also to be filed in the Coating Technical File.

In case of VLCC the amount of dry film thickness measurements is reported 80,000 to 100,000 if measured in accordance with IMO PSPC.

It is questionable that dry film thickness shall be measured by qualified coating inspectors even though you can easily measure it by the device.

During drafting JSTRA Guidelines this issue was disputed very much, and eventually assistants may be used into coating inspections under the coating inspector’s supervision. These assistants shall complete the due training course. These assistants may mitigate the lack of quailed coating inspectors in the marine industry.

IACS defines the coating inspectors’ qualification in the Procedural Requirement No.34 taking into consideration the current small number of qualified inspectors in the marine industry even though IACS is of the opinion that all inspections are to be executed by qualified inspectors and/or inspector with equivalent qualification.

As for qualification of coating inspectors, the scheme of assistant coating inspectors has been adopted by the attendants from the all industries but IACS at Joint Working Group/Coating in Pusan in May, 2007. It may help for lack of qualified coating inspectors. IACS may develop the qualification of the assistant and the



scope of his duties.

4. CLASS NK’s ACTION

4.1 Rules

As you know well, the amendment of regulation 3-2, Ch. II-1, SOLAS has been adopted by MSC82 on 8th December, 2006 and will be effective from 1st July, 2007.

Simultaneously IMO PSPC is to be applied to a ship under IACS CSR of which the building contract is signed on and after 8th December, 2006. IACS Procedural Requirement No. 34 has been also implemented for the smooth application of IMO PSPC.

The amendments of Class NK rules have been approved by the Technical Committee in March, and by Council and Japanese Administration in April, 2007.

The amendments of Class NK rules are only the requirements as class related of IMO PSPC and IACS PR34, such as Type Approval of Coating System, Approval procedures of manufacturers, qualification of coating inspectors, monitoring the coating inspectors and approval of CTF..

4.2 Class NK Guidelines

Class NK has developed both Class NK Guidelines for coating inspectors and NK instructions for Society surveyors.

Class NK Guidelines explains the Society surveyors’ review of inspection records and the inspections of coating inspectors. Class NK Guidelines consists of PR 34, IMO PSPC and JSTRA Guidelines.

As IACS has established JWG/Coatings for drafting IACS Guidelines, IACS Guidelines will timely be incorporated into Class NK Guidelines.

4.3 Class NK Instructions for the Society surveyors

Class surveyor need not be qualified as FROSIO Red or NACE Level III for the review of inspection records. However Class NK gets Society surveyors to have training course of FROSIO or NACE not only in Japan but also China and Korea.

Society surveyors qualified by FROSIO or NACE will give other surveyors the lectures of coating works in order to duly review the inspection records.

NK instructions are being prepared for Society surveyors as follows:-

4.3.1 Type Approval of Coating System

-1 Statement of Compliance issued by MARINTEK or Research Institute of Marine Engineering, Japan Ship-Machinery Quality Control Association.



-2 Approval certificate issued in accordance with the Society’s “Guidance for the Approval and Type Approval of Materials and Equipment for Marine Use”.

-3 Where the shop primer is not removed, either one of the followings is to be confirmed:-

(1) Statement of Compliance or Type Approval Certificate for the coating system consisting of epoxy-base paint and shop primer.

(2) Where neither the statement of compliance nor type approval certificate is available, followings are to be confirmed:-

- statement of compliance nor type approval certificate of the shop primer

- statement of compliance nor type approval certificate for coating system consisting of the said shop primer and other main coating than the intended one

- statement of compatibility between the intended coating system issued by the manufacturer

4.3.2 Approved Course for Coating Inspector’s Equivalent Qualification (program, materials & etc.)

-1. A course may be established by either shipyards, paint manufacturers or any third party, and should be approved by the Society.

-2. A course is to have those syllabus specified by IACS PR 34.

-3. The qualification of course tutor is to follow IACS PR 34.

-4. The Society shall confirm the followings for approval of the course:-

(1) A course tutor: qualification and experience.

(2) List and maintenance instructions of devices and/or equipments for the course.

(3) Syllabus

(4) Test procedures and its criterion.

(5) Procedures of certification for course and tests .

4.3.3 Kick-off meeting on coating (coating system, surface preparation, inspection, recording and etc.)

Shipyards strongly request class to take part in the Kick-off meeting. The Society acknowledge that it is important for the Society to participate in the tripartite kick-off meeting by a shipyard, a ship owner and manufacturer. Therefore the Society surveyor will attend the kick-off meeting as an observer.

Followings are the key agenda of the kick-off meeting:-

-1 Technical Data Sheet of Coating System.

-2 Statement of Compliance or Type Approval Certificate of coating system.



-3 Qualification of coating inspectors

-4 Procedures of surface preparation and coating application

4.3.4 Verification of the coating works(Monitoring the coating inspectors、sampling check of reports

&etc.)

-1 Correspondence of paints

-2 Monitoring coating inspectors’ performance

(1) Primary surface preparation

(2) Block assembly

(3) Erection of blocks

-3 Coating Log/Reports

(1) Each report of surface preparation and each stage of coating works.

(2) Above reports shall be signed by a coating inspector.

4.3.5 Approval of CTF (Coating Technical File)

Followings are to be included in CTF:-

-1 Shipyard work records of coating application, including:

- applied actual space and area (in square meters) of each compartment

- applied coating system

- time of coating, thickness, number of layers, etc.;

- method of surface preparation;

-2 Procedures for inspection and repair of coating system during ship construction;

-3 Coating log issued by the coating inspector – stating that the coating was applied in accordance with the specification of the coating supplier representative and specifying deviations from the specifications

-4 Shipyard’s verified inspection report, including:

- completion date of inspection;

- result of inspection;

- remarks (if given); and

- inspector signature.



-5 Procedures for in-service maintenance and repair of coating system

-6 Approved CTF placed on board.

4 REFERENCE

IMO PSPC:

IMO Resolution MSC.215(82) (adopted on 8 December 2006 at MSC82）Performance Standard for Protective Coatings for Dedicated Seawater Ballast Tanks in All Types of Ships and Double-Side Skin Spaces of Bulk Carriers

IACS PR No.34:

IACS Procedural Requirement （adopted on 8 December 2006 at IACS Council）Applied until the date of application referred to in para.1 of SOLAS Chapter II-1, Part A-1, Reg.3-2, as adopted by resolution MSC.216(82) for the purpose of flexible enforcement of IMO PSPC requirements related to classification in order to solve the difficulties with regard to approved coating systems and coating inspectors.

NK sources:

“Rules for the Survey and Construction of Steel Ships,” Part B, Part CSR-B, and Part CSR-T; and related sections from “Guidance for the Survey and Construction of Steel Ships” and “Guidance for the Approval and Type Approval of Materials and Equipment for Marine Use”

5 CURRENT ACTIVITIES

As every class society develop its own rules and/or guidelines, Class NK Guidelines is continuously updated every time when IMO PSPC, IACS Guidelines and relevant standards are amended.

Class NK joins in the working group with Japan Ship Technology and Research Association and the Japan Society of Naval Architects and Ocean Engineers for improving and/or developing coating guidelines, coating maintenance & etc.


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