BAB V CLASSIFICATION SURVEY FOR NEW KAPAL 5.1 Classification Surveys Before a ship or offshore structure can be registered, it must be surveyed in accordance with technical Rules and regulations of the Society. Once the ship has been surveyed to the satisfaction of the surveyor, classification of the ship is reviewed by the Classification Commitee of the Society. If approved, a certificate of classification or installation registration, as appropriate, is issued and the ship id entered into ClassNK’s Registration of Ships. Basically, in the process of shipbuilding there are three mutually interested parties. They are the shipyard, ship owner, and classification. They perform control function to ensure quality of shipbuilding process. Inspection during process of shipbuilding: a) Inspection by shipyard Shipyard’s quality control standards Quality assurance for customer b) Inspection by ship owner Owner’s specifications Consideration to wards usability and maintenance
Transcript
BAB V
CLASSIFICATION SURVEY FOR NEW KAPAL
5.1 Classification Surveys
Before a ship or offshore structure can be registered, it must be surveyed in
accordance with technical Rules and regulations of the Society. Once the ship has been
surveyed to the satisfaction of the surveyor, classification of the ship is reviewed by the
Classification Commitee of the Society. If approved, a certificate of classification or
installation registration, as appropriate, is issued and the ship id entered into ClassNK’s
Registration of Ships.
Basically, in the process of shipbuilding there are three mutually interested
parties. They are the shipyard, ship owner, and classification. They perform control
function to ensure quality of shipbuilding process.
Inspection during process of shipbuilding:
a) Inspection by shipyard
Shipyard’s quality control standards
Quality assurance for customer
b) Inspection by ship owner
Owner’s specifications
Consideration to wards usability and maintenance
c) Classification Survey
Class requirements and international regulations
To ensure the quality of the ship is always associated with the survey. This is
done not only when the ship was built, but it occurs througghout the lifetime of the ship
from the beginning design to operate the ship. To explain it, we can look the chart life of
ship below.
Chart 5.1 Life of Ship
Survey conducted during the building of new ship, including a survey for material and
equipment manufacturers. To more clearly we can look at chart below:
Chart 5.2 Construction Stage of Ship
Design Construction Service
Plan Approval Classification Surveys
Class Maintenance Surveys
Fabrication
Shipyard
Equipment Installation
Assembly Launching
Manufacturers
Equipment (engine, propeller, etc)
purchase
Materials (steel plates)
Steel Makers
Sea trials
Delivery
purchase
Chart 5.3 Outline of Classification Survey During Construction
Construction StageInspection by S/Y, Owner
Inspection by Surveyor
1. Building Contract
3. Material Order
4. Fabrication
5. AssemblyKeel Lay
SteelCutting
2. Design
Specification
Plan Approval
Acceptance Inspection
Surveys during Fabrication and Assembly process
Block Inspection
Plan Approval
Construction StageInspection by S/Y, Owner
Inspection by Surveyor
6. Outfitting
7. Block Loading
Launching
8. Outfitting
10. Sea TrialsDelivery
Tightness Test and NDT
Final Inspection of Hull Compartments
Performance Test of various Equipment
Installation of Rudder, Keel Alignment etc.
Sea Trial
Stability Experiments, if necessary
Statutory Survey
Delivery
5.2 Acceptance Inspection
5.2.1 Object of inspection
Plate
Propeller
Shaft
Safety equipment (life buoy, life boat)
Navigation equipment
5.2.2 Outgoing inspection and accepyance inspection
The maker or fabricator which producted plat, propeller, anchor, chain,
etc that used at ship must be approved by classification. And then before
installed, the product must have certificate and stamp by classification. Chart
below can describe the steps of inspection.
Chart 5.4 Steps of Inspection Equipment
5.2.3 Purpose of Acceptance inspection
1. To confirm that the parts or material, which are outside manufacture,
have been inspection by the classification society or other appropriate
body.
2. To confirm that they have not been damaged during transportation.
Example of acceptance inspection is shown picture below:
Figure5.1 Check Mill Sheet and The Pate Markings
Confirm the stamp and the entry in the certificate then examine any damage
caused during transportation.
Figure 5.2 Stamp and Certificate
3. To judge the adequacy of the installation of the delivered products to the
particular cessel.
5.3 Hull Structure Installation
5.3.1 Confirmation of scantling of members
Block assembling system
For quick building, hull construction is divided into the bigger
blocks
The size of blocka depend on the crane capacity and size of
block bay etc.
Working drawings (name and information of members,
sequence of assembling)
Importance of control for building schedule
Increase of building rotation and leveling of amount of building
Scantling of members including thickness and steel garde. Especially
primary members such as web frame and girders.
Missing members : Collar plates, carlings, stiffeners and small brackets,
etc.
If abnormality such as imbalance of structure and discontinuity of strength
are found, even if they are built as per drawings, surveyor is to discuss with the
shipyard and suggest correcting them.
Figure 5.3 Missing Brackets
5.3.2 Confirmation of assembly accuracy
Misalignment at cross joint (fillet welding). Especially counter
members to primary members.
Missalignment at butt joint
Distortion members
Figure 5.4 Inapproriate Edge Preparation and Misalignment
Figure 5.5 Misalignment at Block Joint
Figure 6.6 Misalignment at Block Joint
Figure 5.7 Misgnment at Bracket
Misalignment can cause damage
Figure 5.8 Damage Due to Misalgnment
Ripair for misalignment :
Figure 5.9 Repair for Misalignment
5.3.3 Welding
Check point :
1. Welder qualigication
2. Approved welding procedure specification
3. Welding shall be done properly in accordance with above 2.
4. Defect exceeding the critical the limit are to be repaired and re-
checked.
Proper welding is to be done in accordance with WPS
1. Confirmation of edge preparation
a) Same thickness
Figure 5.10 Edge Preparation for Butt Joint without Grooving
Figure 5.11 Edge Preparation for Butt Joint with V and X Type of Grooving
b) Different Thickness
Figure 5.12 Different Thickness of Butt Joint
ClassNK rule requires this tapering not more than 1/3 when there is the
difference in the thickness over 4 mm.
Figure 5.13 Tapering for Different Thickness Joint Preparation
Figure 5.14 Confirmation of Edge Preparation with Welding Gauge
2. Run-off tab
Tabs should be provided at both ends of butt welding,
because defects are likely to occur here.
Tabs should be cut after completion of welding and
surface should be inspected for defects.
Figure 5.15 Run-off tab
Figure 5.16 Various Type of Run-off tab
3. Welding sequence
In case of wrong welding sequence,
Butt joint will be deformed due to heat
End of butt joint overlaps on the seam, and defect is
likely to occur
NDT of welding joint
To know discontinuity in weld metal in surface and subsurface
Figure 5.17 Discontinuity in Weld Metal and The NDT Method
Kind of NDT
We can look at table below for kinds of NDT
Table 5.1 Kinds of NDT
After completin of welding works, the surveyor is to decide locations for NDT and
indicate them in the block plan.
Figure 5.18 Location for NDT
5.3.4 Other inspection
Confirmation of welding and remaining works：
Missing welding and back gouging of critical points
Defects such as under cut, blow hole, lack of leg length, distortion at
welding joint, etc.
Inspection around blocks：
Finished surface of edge preparation and treatment of craters
Sufficient penetration of automatic welding
Scallops on internal members at welding line of plates
Others：
Penetration of internal members through water/oil tight bulkhead
Properly arranged “cut-water scallop”
Air holes and drain holes in tanks
Inspection in special block (stern frame)
Check point ：
Welding between steel plate and cast/forged steel
Slot welding
Tightness test
Alignment of stern frame
Figure 5.19 Inspection of Stern frame for “A” Type Rudder
Inspection inspecial block (shoe piece)
Figure 5.20 Shoe Piece
Block inspection and final inspection
Table 5.2 Advantages of Block Inspection and Final Inspection
5.4 Inspection Before Lounching
5.4.1 Tightness test and structural test
1) Confirmation of tightness and strength
Chart 5.5 Confirmation of Tightness and Strength
2) Plan of Structure Test
Chart 5.6 Plan of Structure Test
3) Hydrostatic test
Hydrostatic test：
Filling water up to a suitable water head
Confirmation of tightness
Confirmation of strength of structure
Objects to be tested：
Double bottom tanks
Deep tanks
Cargo oil tanks and cofferdams of tankers
APT
FPT
Chain Lockers
etc.
Procedure of hydrostatic test
Where it is impracticable to carry out the hydrostatic test on the berth with the
specified test head, the test may be carried out as follows;
1. Hydrostatic test for each compartment on berth under the water head to the level
of ballast water line
2. After that, hydrostatic test for each compartment under the water head specified
above, when ship is afloat
When hydrostatic test for certain compartments is replaced by air test on berth;
a) Some of them including FPT, APT, all COT adjacent to cofferdam and pump
room and ones selected by the surveyor are to be subject to hydrostatic test
in float condition under the water head as specified above.
b) All ballast tanks other than the above selected ones are to be subject to the
hydrostatic test during sea trial with the head of water to the top of the air
pipe.
Example of hydrostatic test (Deep tank)
With the greatest one of followings :
a) Load waterline
b) Top of overflow pipe
c) 2.45m above tank top
(d) 2/3H from tank top
where H is the highest from tank top to upper end of D
Figure 5.21 Hydrostatic Test (Leakage and Strenth test)
4) Air test:
Charge compressed air in the tank up to the required pressure,
Spray leak indicator solution (a kind of soapy water),
In case of any leakage from defective spots, bubbles will be found on it.
Figure 5.22 Air Test (Only Leakage Test)
Figure 5.23 Check point for tightness test
Air Test (Local) Vacuum Test
If the gauge pressure doesn’t decrease, leakage of the box//gasket should be checked.
Figure 5.24 Vacum Test
Air Test (Local) Air Injection Test
This test may be carried out during “in-shop fabrication” or “block inspection”,
in accordance with the approved procedure.
If the gauge pressure doesn’t go up, the “tunnel” or “gap” is stuffed by any
reason. In this case, air tightess should be checked by the other methods.
Figure 5.25 Air Injection Test
5) Hose Test
Pressure (in nozzle): 0.2Mpa
Diameter of nozzle: 12mm or more
Maximum distance: 1.5m
Figure 5.26 Hose Test
Hose test is applicable to shell plating, water-tight deck, water-tight bulkhead,
shaft tunnel, hatchway, etc.
For shell plating of fully welded construction being inspected from both sides
visually, the hose test may be dispensed at the discretion of the surveyor.
5.4.2 Measurement of Pricipal Dimantions
Confirmation of accuracy to the design dimensions
Flatness of keel
Figure 5.27 Standard for Flatness of Keel
Length
Standard for error accordance Japan Standard Quality of Shipyard (JSQS) is ±
50 mm (per 100 m)
Breadth
Standard for error according Japan Standard Quality of Shipyard (JSQS) is ± 15
mm.
Dept
Standard for error according Japan Standard Quality of Shipyard (JSQS) is ±
mm.
Figure 5.28 Standard for Error
Check points ;
Calibartion of the measurement tool
Record of water
Temperature
Time during measurement
Figure 5.29 Flatness of keel, Measurement of L
Measurement of Breadth
a) Set up a pole along the side shell
b) Mark the height of the lower face of keel to the pole
c) Measure the height from the deck line to the lower face of keel
d) Measure the breadth at bottom
Figure 5.30 Measurement of Breadth
5.4.3 Marking
Load lines (ILLC)
� Position of Load line mark, deck line
� Accuracy (±0.5 mm)
� Permanent marking (welding of thin steel plate or punching)
� Color (in contrast with the color of the shell)
Measurement of load lines
Allowable error is 0.5mm
Permanent marking (welding of thin steel plate or punching, Color in
contrast with the color of the shell)
This Marking is on the starboard side
2. Draught Scale （SOLAS II-1）
Marked at fore, aft and midship on both port/ starboard side, every 20 cm of
draught. The height of each letter is to be 10 cm.
The lower edge of the letter should coincide with the actual draught line
(standard ±1 mm, limit ±2 mm)
Figure 5.32 Draught Scale
3. Ship’s identification number (IMO Number) (SOLAS XI/3.4)
Stern, both sides of hull at midship, both sides or front of superstructure
Aftermost bulkhead or hatchway in the machinery space
Figure 5.33 IMO Number at Front of Superstructure
Figurr 5.34 IMO Number at Machinery Space
4. Cargo Compartment Mark (TM 69)
Characters “CC” should be permanently marked at the compartments
included in the calculation of net tonnage
Location of the marking is in principle as follows:
Cargo ship :Outside of hatch coaming
Tanker :Outside of cargo hatch
PCC :Outside of entrance to the hold
LPG carrier:Coaming of tank on upper deck
Figure 5.35 CC (Cargo Compartment) Mark
5.4.4 Corrosion Prevention
5.4.4.1 Painting
Chart 5.7 Corosion Prevention
1. Surface Preparation
Surface preparation
To remove mill scale, rust, & other contaminations on steel surface, as
well, as to provide proper roughness for ensuring better adhesion with
coating
Automated blassting
Below figure shows general layout of shop primer coating machine
Manual blasting
Applicable for various shapes of the objects
Acid pickling
Applicable for pipes and small pieces by using phoshoric acid, etc.
2. Shop Primer
Applied for corrosion protection of steel materials at construction stage, as well
as for reducing work load of surface preparation at painting stage.
Inorganic zinc shop primer
Most propular shop primer due to good durability and a little adverse
defects to the welds.
Zinc epoxy primer
Popular primer used as touch up paint for the surface applied shop
primer due to good durability and quick drying.
Wash primer
Primer used previously due to good adhesion to various kind of coatings
and a little adverse defects to weld.
3. Control of Coating Film Thickness
Wet film gauge
To be used during application and before curing. Dry film thickness
(DFT) can be estimated from wet film thickness (WFT) based on wet/dry
film thickness ratio of the material in the specification.
Dry film gauge
To be used after curing. By using the change in the strength of magnetic
field depending on the distance between steel plate and probe, DFT is
measured.
Figure 5.36 Type of Control Coating
4. Timing of Coating
Main coating is not to be applied until the completion of tightness test.
Welds, which are passed tightness test (e.g. injection test) at block stage,
can be applied with main coating.
Notwithstanding the above, shop primers can be applied prior to
tightness test.
5.4.4.2 Cathodic Protection
Galvanic anode system
Corrosion protective method by fitting less noble metals such as Zinc, aluminum,
magnesium, etc. as sacrificial anode. Generally, outer hull and ballast tank surfaces are
protected by this system in cooperation with coatings.
Impressed current system
Corrosion protective method by using insoluble metal anodes such as Pb or Ti,
which are to be kept in anode potential applied by DC power source installed in E/R
generally. This anode potential works to protect corrosion.
Anodes of aluminum and magnesium generate higher anode potential than zinc, that
looks more effective than zinc. But magnesium anodes are not used for ships in general
due to the risk of hydrogen explosion. And aluminum anodes are not used for ballast
tanks in considering spark hazard and corrosion product from anode itself.
