In Service Survey and IIP 645

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In-service surveys

Svein FlogelandProduct Manager, Offshore Class

DNV Technical seminar on Mobile Offshore UnitsMumbai, February 15th 2008





Slide 3

Retention of Class

Assumptions:

Competently handled

Properly maintained Adequately manned

Obligations:

Submit complete and correct information

Subject vessel to prescribed periodical surveys and surveysof damage, repairs, conversion and alteration

Carry out condition of class

Pay all due fees and expences



Slide 4

Class surveys in operational phase– Why ?

In order to maintain class status, all classed offshore units are required toundergo periodical surveys.

The objective of the surveys is to ascertain that the condition of the structure,machinery installations, equipment and appliances meet, and will continue tomeet, applicable class requirements.

Periodical surveys will in general belong to one of the following categories:

- annual surveys

- intermediate surveys

- renewal surveys

- other complete periodical surveys.



Slide 5

Other Class related Surveys

Survey of Damage Survey of Repairs

Survey of Conversions/Alterations

The surveyor verifies the condition at the time of survey.



Slide 6

Main Survey Principles

The 5 Year Renewal Survey is basic survey for the hull:

All repairs and steel renewals should last at least until next RenewalSurvey.

The Intermediate and Annual Surveys are surveys to verify the predicteddevelopment at the Renewal surveys and initiate corrective actions ifnecessary.



Slide 7

What is a Survey?

Visual overall inspection

Visual close-up examination

Testing

Evaluation and decision making



Slide 8

Maintenance

Advantages of Good Maintenance:

Good coating:

- Limited extent of close-up survey

- Limited extent of thickness

measurements.

Limited scope of class surveys dueto “Good impression”

Disadvantages of Poor Maintenance:

Poor coating:- Annual survey of ballast tanks

- Annual mapping of areas with

“Substantial Corrosion”

Extended scope of Class surveydue to “Poor impression”



Slide 9

Survey planning parameters

Important factors:

•Age•Structural design•Corrosion potential•History (service type,damage, repairs)



Slide 10

Annual Surveys

Annual surveys are normally visual examinations to ascertain the generalcondition of the unit or relevant item.

The survey will normally cover systems and parts for:

- structure and equipment

- machinery and safety systems.

A more thorough annual survey may be specified for particular structures,

machinery installations or equipment due to consequences of failure or age.

Unless otherwise stated, annual surveys shall be carried out within a time period

3 months either side of the due date.



Slide 11

Intermediate Surveys

Intermediate surveys include visual examinations of hull structures, machinery,and electrical installations and equipment in order to ascertain that the unitcontinues to comply with class requirements.

Testing is specified for particular items as necessary due to consequence of

failure or age.

Unless otherwise stated, intermediate surveys shall be performed at the second orthird annual survey after the credited date of the renewal survey.

The survey shall normally be carried out in sheltered waters. Survey on locationmay be acceptable provided that the underwater inspection is performed inaccordance with an approved procedure, and using approved personnel andequipment.

The survey shall, in general, be carried out as the annual survey, but withextended visual inspection and non-destructive testing of the structure as given inrelevant rules and inservice inspection programme



Slide 12

Renewal Surveys

Renewal surveys are major surveys of hull structures, machinery installations andequipment.

Renewal surveys include visual examinations, measurements and tests in orderto confirm that the unit or installation complies with the relevant DNV classrequirements and is in satisfactorily maintained condition to continue the intendedservice.

Renewal surveys for hull, machinery installations and equipment shall be carriedout at 5-yearly intervals

DNV may accept that renewal surveys for hull, machinery installations andequipment are commenced before due date, provided that the surveys arecompleted:

- not later than 12 months after the commencement- in any case not later than expiry date of the classification certificate including possible

postponement granted.



Slide 13

Renewal surveys (contd..)

Any required repairs identified from survey examinations and testsshall normally be carried out:

- before the renewal survey is regarded as complete

- not later than the expiry date of the classification certificate

including possible postponement granted.

In certain cases, DNV may accept that minor deficiencies are

rectified within a specified time limit not exceeding 3 months afterexpiry date of the classification certificate



Slide 14

Other periodical surveys

The additional class notation's requirements shall be adhered to by the owneras conditions for the retention of these class notations, as applicable.

The surveys may be performed as annual surveys, intermediate surveys and orcomplete periodical surveys,

A complete periodical survey is a major survey related to an additional class

notation, system or component.



Slide 15

RegisterReport

Checklist

Internal Reporting External Reporting

QuickReports

FinalReports

Certificates

ExperienceFeedback

(EF)

THE UNIT

Immediate dispatch

Dispatch within 10 days

Dispatch if applicable

DNV Reporting System, Units in Operation

DNV Headoffice

Owner



Slide 16

Condition of Class (CC) or (CA) - Definition

Conditions of Class (CC) to be carried out are requirements to the effectthat specified operations (e.g repairs, adjustments, reinforcements orsurveys) are to be carried out within a specified time limit ( if necessary

immediately).

Conditions of Authority (CA) covers requirements outside the scope ofclassification.





Slide 18

Survey Due Dates

The due date of a periodical survey will depend on the survey interval,measured from one of the following events,(whichever is relevant):

- date of class assignment

- date of commissioning

- due date of the previous corresponding survey

- date of completion of the previous corresponding survey.



Slide 19

Survey Windows

A survey “window” exists around each due date, consisting of a window before(WB) and window after (WA). The total survey window represents the overallallowable period within which a survey shall be initiated and completed.

Surveying should normally be undertaken during the survey window. Under

certain conditions, however, DNV may allow surveys to be initiated prior toentering the survey window

Failing to complete surveys before the end of the survey window or expiry of

allowed postponement will result in warning and potential suspension of class.



Slide 20

Survey Time Windows



Slide 21

Survey Intervals



Slide 22

Class Survey Schedule

Year 0 Year 1 Year 2 Year 3 Year 4 Year 5

1stAnnual

2ndAnnual

3rdAnnual

4thAnnual

Renewalsurvey

Intermediate Renewal

Commencement CommencementCompletion Completion

Survey window of +/- 3months from due date

Minimum frequency of inspection is set by IACS unified requiremeMinimum frequency of inspection is set by IACS unified requirementsnts



Slide 23

Periodical Surveys - Main Class



Slide 24

Periodical surveys, additional class



Slide 25

Periodical Surveys, additional class (contd.)



Slide 26

Postponement of periodical surveys

DNV may accept to postpone periodical surveys beyond the survey windowupon consideration in each separate case.

Where postponement is granted, a condition of class (CC) will be issued stating

the time limit for the postponement period.

Annual and intermediate surveys shall normally not be postponed.

Upon the owner's request, an extension of the validity of the classificationcertificate by maximum 3 months may be granted in exceptional cases.



Slide 27

100 % SURVEY OF A VLCC WOULD REQUIRE

Climbing 10,000 m.

Examination of 300,000 m2.

Examination of 1,200 km hull

welding.

Examination of 100 km

longitudinals.

Examination of 100,000 hull

elements.



Slide 28

In-service Considerations

How are the

loads taken up

by the

structure?

Consequence

of a crack in

this detail?

Where is itlikely to find

cracks?



Slide 29

In-service Inspection Programme

MAIN OBJECTIVE:

Improve survey quality

HOW:

Obtain additional information (from Owner) Owner to be prepared

Access to and cleaning of structure planned

Evaluation of design, damages, corrosion protection





Slide 31

IN-SERVICE INSPECTION PROGRAMME

TAKES INTO ACCOUNT

Rig design criteria

Workmanship

Operational area

Damage history of rig Total experience



Slide 32

Example: In-service Inspection programme for a JU



Slide 33

Abbrev.:

INT = Internal A = 100%(2

EXT = External B = 50%(2

Special Areas are those sections of Primary Structurewhich are in way of critical load transfer points, stressconcentrations, etc.These special areas are designated "SP".

V = Visual Insp. C = 25%(2

NDT = None DestructiveTesting

X = (2-5%) Spot Check(2

See also Sec. 8,Special Considerations

ANNUALSURVEY INTERMEDIATESURVEY RENEWALSURVEY

INT EXT INT EXT INT EXTCONNECTIONS

SPECIAL AREAS (SP)

V N D T

V N D T

V N D T

V N D T

V N D T

V N D T

SP1 Leg to spudcan A X A A A A

SP2 Leg nodes X A A X1)

SP3 Connections of primary members in jackhouse A A X A A

SP4 Main barge girder/bulkhead connections X X X X A A

Attachments of:

SP5 Crane/gangway pedestal and top flange A A A X A X A A A A

SP6 Support of drill floor A A A A

SP7 Helideck support X X X C X A X A C

SP8 Other attachment/support connections X X X X X A X A X

SP =Special Area are those sections of Primary Structure which are in way of critical load transfer point, stress concentrations andfatigue sensitive details (See DNV-OS-C103 Sec.2, B and DNV-OS-C201 Sec.11, B.

1) = At levels which have been in way of lower guides in operation, upper guides in transit and in way of spudcans.

2) = Of the total number of these parts



Slide 34

Legs

Special areas





Slide 36

Adapting to modern maintenance systems

DNV has adopted to modern maintenance techniques by allowing for alternativesurvey arrangements.

Examples of the most common alternatives to the traditional 'open up inspection

techniques' are: Continuous surveys allowing the complete Renewal Survey or parts thereof to be

carried out on a rotational basis according to an agreed and accepted sequence

Survey arrangements based on owner's approved planned inspection and/or

maintenance systems (PMS). Such arrangement may be accepted for mechanical,electrical and instrumentation systems and components. When implemented, theunit's own PMS will be taken as basis for class surveys

Survey based on condition monitoring systems for machinery/systems and/or hull

Acceptance of inspection plans based on Risk Based Inspection (RBI) techniques



Slide 37

Collection and handling of experience

Reported damages such as cracks, serious corrosion, indentations etc. loggedin central damage data base

• currently holds more than 4000 entries.

Data balanced against other sources of information and are used for: Trend analysis

Highlighting of typical defects

Initiation of safety alerts and corrective actions

Modification of survey frequency and extent as defined in the In-service Inspectionprogram

Improvement of classification rules



Slide 38

DNV ’s service philosophy

Single point of contact for your convenience through dedicated rig co-ordinators.

rig co-ordinator assigned for each classed unit

has a key role in planning surveys in co-operation with owner qualified and experienced MOU surveyors

acts as focal point for DNV towards the owner, and will interact with the surveyorsand facilitate experience transfer through an established network

Global network of offices in all major offshore and shipping centres withmanagers, technically competent and authorised to make most decisions

locally.

Efficient working and approval processes;

All personnel world-wide working and updating common online single informationcarrier (DNV electronic production system NAUTICUS)

Survey information, inspection program and relevant check lists are made availablethrough Nauticus facilitates reporting and follow-up.



Slide 39

A day in the surveyor’s life…

Includes the use of very traditional instruments!

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In Service Survey and IIP 645

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