offshore mooring chain cables and accessories

8/10/2019 Offshore Mooring Chain Cables and Accessories

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NR 216, Ch 4, Sec 2

April 2005 with amendments May 2006 Bureau Veritas 165

SECTION 2 OFFSHORE MOORING CHAIN CABLES ANDACCESSORIES

1 General requirements

1.1 Scope

1.1.1 The requirements of this Section apply to the materi-als, design, manufacture and testing of offshore mooringchain and accessories intended to be used for applicationsuch as: mooring of mobile offshore units, mooring of float-ing production units, mooring of offshore loading systems

and mooring of gravity based structures during fabrication.Mooring equipment covered are common links, connectingcommon links (splice links), enlarged links, end links,detachable connecting links (shackles), end shackles, swiv-els and swivel shackles.

1.2 Chain grades

1.2.1 Depending on the nominal tensile strength of thesteels used for manufacture, chains are to be subdividedinto three grades, i.e.: QR3, QR3S and QR4.

1.3 Approval of chain manufacturers

1.3.1 Offshore mooring chain are to be manufactured onlyby works approved by the Society. For this purpose approvaltests are to be carried out, the scope of which is to includeproof and breaking load tests, measurements and mechani-cal tests including fracture mechanics tests.

1.3.2 Manufacturers are to submit for review and approvalthe sequence of operations from receiving inspection toshipment and details of the following manufacturing pro-cesses:

a) bar heating and bending including method, tempera-tures, temperature control and recording

b) flash welding including current, force, time and dimen-sional variables as well as control and recording ofparameters

c) flash removal incl method and inspection

d) stud insertion method

e) heat treatment incl. furnace types, means of specifying,controlling and recording of temperature and chainspeed and allowable limits, quenching bath andagita-tion, cooling method after exit

f) proof and break loading incl. method/machine, meansof horizontal support (if applicable), method of mea-

surement, recording

g) non-destructive examination procedures.

1.3.3 Calibration of furnaces shall be verified by measure-ment and recording of actual link temperature (surface andinternal).

1.4 Approval of quality system at chain

manufacturers

1.4.1 Chain manufacturers are to have a documented andeffective quality system approved by the Society. The provi-

sion of such a quality system is required in addition to, andnot in lieu of, the witnessing of tests by a Surveyor as speci-fied in this Section.

1.5 Approval of steel mills for rolled bars

1.5.1 Bar material intended for chain and accessories are tobe manufactured only by works approved by the Society.The approval is limited to a nominated supplier of bar mate-rial. If a chain manufacturer wishes to use material from anumber of suppliers, separate approval tests must be carriedout for each supplier.

Approval will be given only after successful testing of thecompleted chain. The approval will normally be limited to adiameter equal to that of the bars tested.

1.5.2 The steelmaker is to submit a specification of thechemical composition of the bar material, which must beapproved by the Society and by the chain manufacturer.

For Grade QR4 chain the steel should contain a minimumof 0,20 per cent of molybdenum.

1.5.3 A heat treatment sensitivity study simulating chainproduction conditions shall be applied in order to verifymechanical properties and establish limits for temperatureand time combinations.

1.5.4 The bar manufacturer is to provide evidence that thematerial is resistant to strain ageing, temper embrittlementand hydrogen embrittlement.

1.6 Approval of forges and foundries for

accessories

1.6.1 Forges and foundries intending to supply finished orsemi-finished accessories are to be approved by the Society.The scope of approval is to be agreed with the Society.

1.6.2 Manufacturers intending to supply accessories inmachined condition (e.g. Kenter type shackles) are to sub-mit detailed drawings for approval.


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NR 216, Ch 4, Sec 2

166 Bureau Veritas April 2005 with amendments May 2006

2 Materials

2.1 Scope

2.1.1 These requirements apply to rolled steels, forgings

and castings used for the manufacture of offshore mooringchain and accessories.

2.2 Rolled steel bars

2.2.1 Steel manufacture

The steels are to be manufactured by basic oxygen, electricfurnace or such other process as may be speciallyapproved. All steels are to be killed and fine grain treated.

2.2.2 Chemical composition

The chemical composition of ladle samples of each heat isto be determined by the steel maker and is to comply with

the approved specification.

2.2.3 Mechanical tests

a) Bars of the same nominal diameter are to be presentedfor test in batches of 50 tonnes or fraction thereof fromthe same heat. Test specimens are to be taken frommaterial heat treated in the same manner as intended forthe finished chain.

b) Each heat of Grade QR3S and QR4 steel bars is to betested for hydrogen embrittlement. In case of continu-ous casting, test samples representing both the begin-ning and the end of the charge shall be taken. In case ofingot casting, test samples representing two differentingots shall be taken.

Two (2) tensile test specimens shall be taken from thecentral region of bar material which have been simu-lated heat treated. The specimens shall preferably havea diameter of 20 mm, alternatively 14 mm. One speci-men is to be tested within max. 3 hours after machining.For a 14 mm specimen, the time limit is 1,5 hours.(Alternatively, the specimen may be cooled to 60Cimmediately after machining and kept at that tempera-ture for a period of max. 5 days). The other specimen isto be tested after baking at 250C for 4 hours, alterna-tively 2 hours for 14 mm specimen.

A slow strain rate < 0,0003 s1must be used during theentire test, until fracture occurs (This means approx. 10minutes for a 20 mm specimen).

Tensile strength, elongation and reduction of area are tobe reported. The requirement for the test is:

Z1/ Z20,85where:

Z1 : Reduction of area without baking

Z2 : Reduction of area after baking.

If the requirement Z1 / Z2 0,85 is not met, the bar

material may be subjected to a hydrogen degassingtreatment after agreement with the Society. New testsshall be performed after degassing.

c) For all grades, one tensile and three Charpy V-notchspecimens are to be taken from each sample selected.The test specimens are to be taken at approx. one-thirdradius below the surface, as shown in Fig 1.

The results of all tests are to be in accordance with theappropriate requirements of Tab 1.

d) Re-test requirements for tensile tests are given in Ch 1,Sec 2, [2.3].

e) Re-test requirements for Charpy V-notch impact tests aregiven in Ch 1, Sec 2, [4.4].

f) Failure to meet the requirements will result in rejectionof the batch represented unless it can be clearly attribut-able to improper simulated heat treatment.

Figure 1 : Sampling of steel bars, forgings and castings

Table 1 : Mechanical properties of grades QR3, QR3S and QR4

Specimen for notchedbar impact test

Tensilespecimen

r/3

r/3

GradeYield stress

(N/mm2)minimum(1)

Tensile strength

(N/mm2)

minimum(1)

Elongation(%)

minimum

Reduction(3)of area (%)minimum

Charpy V-notch impact tests

Test temperature(C)(2)

Average energy Jminimum

Average energy flashweld J minimum

QR3 410 690 17 50 0

20

60

40

50

30

QR3S 490 770 15 50 0

20

65

45

53

33

QR4 580 860 12 50 20 50 36

(1) Aim value of yield to tensile ratio: 0,92 max.

(2) At the option of the Society, the impact test of grade QR3 and QR3S may be carried out at either 0C or 20C.

(3) Reduction of area of cast steel is to be for grades QR3 and QR3S: min. 40%, for QR4: min. 35%, see 2.4.4.


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NR 216, Ch 4, Sec 2


2.2.4 Tolerances on dimensions

The diameter and roundness shall be within the tolerancesspecified in Tab 2, unless otherwise agreed.

Table 2 : Tolerances on dimensions of bar stock

2.2.5 Non-destructive examination and repair

The bars shall be free of pipe, cracks and flakes. Bar mate-rial is to be subjected to ultrasonic examination at an appro-priate stage of the manufacture.

One hundred percent of the bar material is to be examinedby magnetic particle or eddy current methods. The barsshall be free of injurious surface imperfections such asseams, laps and rolled-in mill scale. Provided that theirdepth is not greater than 1% of the bar diameter, longitudi-nal discontinuities may be removed by grinding and blend-ing to a smooth contour.

The frequency of NDE may be reduced at the discretion ofthe Society provided it is verified by statistical means thatthe required quality is consistently achieved.

2.2.6 Marking

Each bar is to be stamped with the steel grade designationand the charge number (or a code indicating the chargenumber) on one of the end surfaces. Other marking meth-ods may be accepted subject to agreement.

2.3 Forged steel

2.3.1 Forged steels used for the manufacture of accessoriesmust be in compliance with specifications submitted andapproved.


The chemical composition of ladle samples of each heat isto be determined by the steel maker and is to comply withthe approved specification.

2.3.3 Heat treatment

Finished forgings are to be properly heat treated in compli-ance with specifications submitted and approved.

2.3.4 Mechanical properties

The forgings must comply with the mechanical propertiesgiven in Tab 1, when properly heat treated.


For test sampling, forgings of similar dimensions (diametersdo not differ by more than 25mm) originating from the sameheat treatment charge and the same heat of steel are to be

combined into one test unit. From each test unit one tensileand three impact test specimens are to be taken and tested.For the location of the test specimens see Fig 1.

2.3.6 Ultrasonic examination

The forgings are to be subjected to ultrasonic examination

at an appropriate stage of manufacture and in compliancewith the standard submitted and approved.

2.3.7 Marking

Marking is to be similar to that specified in [2.2.6].

2.4 Cast steel

2.4.1 Cast steels used for the manufacture of accessoriesmust be in compliance with specifications submitted andapproved.


The chemical composition of ladle samples of each heat is

to be determined by the steel maker and is to comply withthe approved specification.


All castings are to be properly heat treated in compliancewith specifications submitted and approved.

2.4.4 Mechanical properties

The castings must comply with the mechanical propertiesgiven in Tab 1. The requirement for Reduction of Area is,however, reduced to 40% for grades QR3 and QR3S and35% for grade QR4.


For test sampling, castings of similar dimensions originatingfrom the same heat treatment charge and the same heat ofsteel are to be combined into one test unit. From each testunit one tensile and three impact test specimens are to betaken and tested. For the location of the test specimens seeFig 1.

2.4.6 Ultrasonic examination

The castings are to be subjected to ultrasonic examinationin compliance with the standard submitted and approved.

2.4.7 Marking

Marking is to be similar to that specified in [2.2.6].

2.5 Materials for studs

2.5.1 The studs are to be made of steel corresponding tothat of the chain or in compliance with specifications sub-mitted and approved. In general, the carbon content shouldnot exceed 0,25% if the studs are to be welded in place.

3 Design and chain manufacture

3.1 Design

3.1.1 Drawings giving detailed design of chain and acces-

sories made by or supplied through the chain manufacturerare to be submitted for approval. Typical designs are givenin ISO 1704:1991.

Nominaldiameter (mm)

Tolerance ondiameter (mm)

Tolerance on roundnessdmaxdmin(mm)

less than25 0 +1,0 0,60

25 - 35 0 +1,2 0,80

36 - 50 0 +1,6 1,10

51 - 80 0 +2,0 1,50

81 - 100 0 +2,6 1,95

101 - 120 0 +3,0 2,25

121 - 160 0 +4,0 3,00


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NR 216, Ch 4, Sec 2


In addition, drawings showing the detailed design of thestud shall be submitted for information. The stud shall givean impression in the chain link which is sufficiently deep tosecure the position of the stud, but the combined effect ofshape and depth of the impression shall not cause any harm-ful notch effect or stress concentration in the chain link.

Machining of Kenter shackles shall result in fillet radiusmin. 3% of nominal diameter.

3.2 Manufacturing process

3.2.1 Offshore mooring chains shall be manufactured incontinuous lengths by flash butt welding and are to be heattreated in a continous furnace; batch heat treatment is notpermitted.

The use of joining shackles to replace defective links is sub-ject to the written approval of the end purchaser in terms ofthe number and type permitted. The use of connecting com-mon links is restricted to 3 links in each 100 m of chain.

3.3 Manufacturing Process Records

3.3.1 Records of bar heating, flash welding and heat treat-ment shall be made available for inspection by the Sur-veyor.

3.3.2 Bar heating

For electric resistance heating, the heating phase shall becontrolled by an optical heat sensor. The controller shall bechecked at least once every 8 hours and records made.

For furnace heating, the heat shall be controlled and thetemperature continuously recorded using thermocouples in

close proximity to the bars. The controls shall be checked atleast once every 8 hours and records made.

3.3.3 Flash welding

The following welding parameters shall be controlled dur-ing welding of each link:

a) Platen motion

b) Current as a function of time

c) Hydraulic pressure

The controls shall be checked at least every 4 hours andrecords made.


Chain shall be austenitized, above the upper transformationtemperature, at a combination of temperature and timewithin the limits established.

When applicable, chain shall be tempered at a combinationof temperature and time within the limits established.

Temperature and time or temperature and chain speed shallbe controlled and continuously recorded.

3.4 Mechanical properties

3.4.1 The mechanical properties of finished chain andaccessories are to be in accordance with Tab 1. For thelocation of test specimens see Fig 1 and Fig 2.

3.5 Proof and breaking test loads

3.5.1 Chains and accessories are to withstand the proofand break test loads given in Tab 3.

Figure 2 : Sampling of chain links

Table 3 : Formulas for proof and break test loads of studlink chain cables, weight and length over 5 links

Grade QR3 Grade QR3S Grade QR4

Proof test load (kN) 0,0148 d2(44 0,08 d) 0,0180 d2(44 0,08 d) 0,0216 d2(44 0,08 d)

Break test load (kN) 0,0223 d2(44 0,08 d) 0,0249 d2(44 0,08 d) 0,0274 d2(44 0,08 d)

Chain weight (kg/m) 0,0219 d2

Length over 5 links

Minimum (mm) 22 d

Maximum (mm) 22,55 d

Specimen for notchedbar impact test

Tensilespecimen

r/3

r/3

Specimen for notchedbar impact testr/3


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NR 216, Ch 4, Sec 2


3.6 Freedom from defects

3.6.1 All chains are to have a workmanlike finish consistentwith the method of manufacture and be free from defects.Each link is to be examined in accordance with [4.5] usingapproved procedures.

3.7 Dimensions and tolerances

3.7.1 The shape and proportion of links and accessoriesmust conform to ISO 1704:1991 or the designs speciallyapproved.

3.7.2 The following tolerances are applicable to links:

a) Diameter measured at the crown:

up to 40 mm nominal diameter: 1 mm

over 40 up to 84 mm nominal diameter: 2 mm

over 84 up to 122 mm nominal diameter: 3 mm

over 122 mm nominal diameter: 4 mmThe plus tolerance may be up to 5% of the nominaldiameter.

The cross sectional area at the crown must have no neg-ative tolerance.

b) Diameter measured at locations other than the crown:

The diameter is to have no negative tolerance. The plustolerance may be up to 5% of the nominal diameter. Theapproved manufacturers specification is applicable tothe plus tolerance of the diameter at the flash butt weld.

c) The allowable manufacturing tolerance on a length offive links is + 2,5%, but is not to be negative.

d) All other dimensions are subject to a manufacturing tol-erance of 2,5%, provided always that all parts fittogether properly.

e) Studs must be located in the links centrally and at rightangles to the sides of the link. The following tolerancesare acceptable provided that the stud fits snugly and itsends lie flush against the inside of the link:

Maximum off-centre distance "X" is 10% of the nom-inal diameter.

Maximum deviation from the 90 position is 4.

The tolerances are to be measured in accordance withFig 3.

Figure 3 : Manufacturing tolerances

3.7.3 The following tolerances are applicable to accesso-ries:

a) Nominal diameter: + 5%, 0%

b) Other dimensions: 2,5%.

3.8 Welding of studs

3.8.1 A welded stud may be accepted for grade QR3 andQR3S chains. Welding of studs in grade QR4 chain is notpermitted unless specially approved.

3.8.2 Where studs are welded into the links this is to becompleted before the chain is heat treated.

3.8.3 The stud ends must be a good fit inside the link andthe weld is to be confined to the stud end opposite to theflash butt weld. The full periphery of the stud end is to bewelded unless otherwise approved.

3.8.4 Welding of studs both ends is not permitted unlessspecially approved.

3.8.5 The welds are to be made by qualified welders usingan approved procedure and low-hydrogen approved con-sumables.

3.8.6 The size of the fillet weld shall as a minimum be asper API Specification 2F.

3.8.7 The welds are to be of good quality and free fromdefects such as cracks, lack of fusion, gross porosity andundercuts exceeding 1 mm.

3.8.8 All stud welds shall be visually examined. At least10% of all stud welds within each length of chain shall beexamined by dye penetrant or magnetic particles after prooftesting. If cracks or lack of fusion are found, all stud weldsin that length are to be examined.

3.9 Connecting common links

3.9.1 Single links to substitute for test links or defectivelinks without the necessity for re-heat treatment of thewhole length are to be made in accordance with anapproved procedure. Separate approvals are required foreach grade of chain and the tests are to be made on themaximum size of chain for which approval is sought.

3.9.2 Manufacture and heat treatment of connecting com-mom link is not to affect the properties of the adjoininglinks. The temperature reached by these links is nowhere toexceed 250C.

3.9.3 Each link is to be subjected to the appropriate proofload and non-destructive examination as detailed in Tab 3and in [4.5]. A second link shall be made identical to theconnecting common link; the link shall be tested andinspected as per [4.4] and [4.5].

3.9.4 Each connecting common link is to be marked on thestud in accordance with [4.7] plus a unique number for thelink. The adjoining links are also to be marked on the studs.

a

d

A

Off-centre distance :

X =A - a 2


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NR 216, Ch 4, Sec 2


4 Testing and inspection of finishedchain

4.1 General

4.1.1 All chain is to be subjected to proof load tests, breakload tests and mechanical tests after final heat treatment inthe presence of a Surveyor. Where the manufacturer has aprocedure to record proof loads and the Surveyor is satisfiedwith the adequacy of the recording system, he need not wit-ness all proof load tests. The Surveyor is to satisfy himselfthat the testing machines are calibrated and maintained in asatisfactory condition.

Prior to test and inspection the chain is to be free fromscale, paint or other coating. The chain shall be sand or shotblasted to meet this requirement.

4.2 Proof and break load tests

4.2.1 The entire length of chain shall withstand the proofload specified in Tab 3 without fracture and shall not crackin the flash weld. The load applied shall not exceed theproof load by more than 10% when stretching the chain.Where plastic straining is used to set studs, the applied loadis not to be greater than that qualified in approval tests.

4.2.2 A break-test specimen consisting of at least 3 links isto be either taken from the chain or produced at the sametime and in the same manner as the chain. The test fre-quency is to be based on tests at sampling intervals accord-

ing to Tab 4 provided that every cast is represented. Eachspecimen shall be capable of withstanding the break loadspecified without fracture and shall not crack in the flashweld. It shall be considered acceptable if the specimen isloaded to the specified value and maintained at that loadfor 30 seconds.

If the loading capacity of the testing machine is insufficient,another equivalent method shall be agreed with the Society.

Table 4 : Frequency of break and mechanical tests

4.3 Dimensions and dimensional tolerances

4.3.1 After proof load testing measurements are to be takenon at least 5 per cent of the links in accordance with [3.7].

4.3.2 The entire chain is to be checked for the length, fivelinks at a time. By the five link check the first five links shallbe measured. From the next set of five links, at least twolinks from the previous five links set shall be included. Thisprocedure is to be followed for the entire chain length. Themeasurements are to be taken preferably while the chain isloaded to 5-10% of the minimum proof load. The links heldin the end blocks may be excluded from this measurement.

4.4 Mechanical tests

4.4.1 Links of samples detached from finished, heat treatedchain shall be sectioned for determination of mechanicalproperties. A test unit shall consist of one tensile and nineimpact specimens. The tensile specimen shall be taken inthe side opposite the flash weld. Three impact specimensshall be taken across the flash weld with the notch centeredin the middle. Three impact specimens shall be taken acrossthe unwelded side and three impact specimens shall betaken from the bend region.

The test frequency is to be based on tests at sampling inter-vals according to Tab 4 provided that every cast is repre-sented. Mechanical properties shall be as specified in Tab 1.

The frequency of impact testing in the bend may be reducedat the discretion of the Society provided it is verified by sta-tistical means that the required toughness is consistently

achieved.

4.5 Non-destructive examination

4.5.1 After proof testing, all surfaces of every link shall bevisually examined. Burrs, irregularities and rough edgesshall be contour ground. Links shall be free from milldefects, surface cracks, dents and cuts, especially in thevicinity where gripped by clamping dies during flash weld-ing. Studs shall be securely fastened.

4.5.2 Magnetic particles shall be employed to examine theflash welded area including the area gripped by the clamp-

ing dies. Procedures and equipment in accordance withthose approved shall be used.

Frequency of examination shall be every link.

Link surface at the flash weld shall be free from cracks, lackof fusion and gross porosity.

4.5.3 Ultrasonics shall be employed to examine the flashweld fusion. Procedures and equipment in accordance withthose approved shall be used. On-site calibration standardsfor chain configurations shall be approved.

Frequency of examination shall be every link.

The flash weld shall be free from defects causing ultrasonicback reflections equal to or greater than the calibrationstandard.

Nominal chain diameter(mm)

Maximum sampling interval(m)

Min - 48 91

49 - 60 110

61 - 73 131

74 - 85 152

86 - 98 175

99 - 111 198

112 - 124 222

125 - 137 250

138 - 149 274

150 - 162 297

163 - 175 322


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NR 216, Ch 4, Sec 2


4.6 Retest, rejection and repair criteria

4.6.1 If the length over 5 links is short, the chain may bestretched by loading above the proof test load specified pro-vided that the applied load is not greater than that approvedand that only random lengths of the chain need stretching.

If the length exceeds the specified tolerance, the overlengthchain links shall be cut out and [4.6.2] shall apply.

4.6.2 If single links are found to be defective or to not meetother applicable requirements, defective links may be cutout and a connecting common link inserted in their place.The individual heat treatment and inspection procedure ofconnecting common links is subject to the Society'sapproval.

Other methods for repair is subject to the written approvalof the Society and the end purchaser.

4.6.3 If a crack, cut or defect in the flash weld is found by

visual or magnetic particle examination, it shall be grounddown no more than 5% of the link diameter in depth andstreamlined to provide no sharp contours. The final dimen-sions must still conform to the agreed standard.

4.6.4 If indications of interior flash weld defects in refer-ence to the accepted calibration standards are detected dur-ing ultrasonic examination, [4.6.2] shall apply.

4.6.5 If link diameter, length, width and stud alignment donot conform to the required dimensions, these shall becompared to the dimensions of 40 more links; 20 on eachside of the affected link. If a single particular dimension failsto meet the required dimensional tolerance in more than 2

of the sample links, all links shall be examined and [4.6.2]shall apply.

4.6.6 If a break load test fails, a thorough examination withthe Surveyor informed in a timely manner is to be carriedout to identify the cause of failure. Two additional break testspecimens representing the same sampling length of chainare to be subjected to the break load test. Based upon satis-factory results of the additional tests and the results of thefailure investigation, it will be decided what lengths ofchain can be accepted. Failure of either or both additionaltests will result in rejection of the sampling length of chainrepresented and [4.6.2] shall apply.

4.6.7 If a link fails during proof load testing, a thoroughexamination with the Surveyor informed in a timely manneris to be carried out to identify the probable cause of failureof the proof test. In the event that two or more links in theproof loaded length fail, that length is to be rejected. Theabove failure investigation is to be carried out especiallywith regard to the presence in other lengths of factors orconditions thought to be causal to failure.

In addition to the above failure investigation, a break testspecimen is to be taken from each side of the one failedlink, and subjected to the breaking test. Based upon satis-factory results of both break tests and the results of the fail-ure investigation, it will be decided what length of chain

can be considered for acceptance. Failure of either or bothbreaking tests will result in rejection of the same proofloaded length.

Replacement of defective links is to be in accordance with[4.6.2].

4.6.8 Re-test requirements for tensile tests are given in Ch1, Sec 2, [2.3]. Failure to meet the specified requirements ofeither or both additional tests will result in rejection of the

sampling length of chain represented and [4.6.2] shallapply.

4.6.9 Re-test requirements for Charpy V-notch impact testsare given in Ch 1, Sec 2, [4.4].

Failure to meet the requirements will result in rejection ofthe sampling length represented and [4.6.2] shall apply.

4.7 Marking

4.7.1 The chain shall be marked at the following places:

at each end

at intervals not exceeding 100 m

on connecting common links

on links next to shackles or connecting common links.

All marked links shall be stated on the certificate, and themarking shall make it possible to recognize leading and tailend of the chain. In addition to the above required marking,the first and last common link of each individual chargeused in the continuous length shall be adequately andtraceable marked.

The marking shall be permanent and legible throughout theexpected lifetime of the chain.

4.7.2 The chain shall be marked on the studs as follows:

chain grade certificate No.

Society's stamp.

The Certificate number may be exchanged against anabbreviation or equivalent. If so, this shall be stated in thecertificate.

The chain certificate shall contain information on numberand location of connecting common links. The certificatenumber and replacement link number may be exchangedagainst an abbreviation or equivalent. If so, this shall bestated in the certificate.

4.8 Documentation

4.8.1 A complete Chain Inspection and Testing Report inbooklet form shall be provided by the chain manufacturerfor each continous chain length. This booklet shall includeall dimensional checks, test and inspection reports, NDTreports, process records, photographs as well as any non-conformity, corrective action and repair work.

Individual certificates are to be issued for each continuoussingle length of chain.

All accompanying documents, appendices and reports shallcarry reference to the original certificate number.

The manufacturer will be responsible for storing, in a safeand retrievable manner, all documentation produced for aperiod of at least 10 years.


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NR 216, Ch 4, Sec 2


5 Testing and inspection of accessories

5.1 General

5.1.1 All accessories are to be subjected to proof load tests,break load tests and mechanical tests after final heat treat-ment in the presence of a Surveyor. Where the manufac-turer has a procedure to record proof loads and theSurveyor is satisfied with the adequacy of the recording sys-tem, he need not witness all proof load tests. The Surveyoris to satisfy himself that the testing machines are calibratedand maintained in a satisfactory condition.

Prior to test and inspection the chain accessories are to befree from scale, paint or other coating.

5.2 Proof and break load tests

5.2.1 All accessories are to be subjected to the proof loadspecified for the corresponding chain.

5.2.2 Chain accessories are to be tested at the break loadprescribed for the grade and size of chain for which they areintended. At least one accessory out of every batch or every25 accessories, whichever is less, is to be tested. For indi-vidually produced accessories or accessories produced insmall batches, alternative testing will be subject to specialconsideration.

The accessories which have been subjected to the breakload test are to be destroyed and not used as part of an out-fit, with the exceptions given in [5.2.3].

5.2.3 Where the accessories are of increased dimension or

alternatively a material with higher strength characteristicsis used, they may be included in the outfit at the discretionof the Classification Society, provided that:

a) the accessories are successfully tested at the prescribedbreaking load appropriate to the chain for which theyare intended, and

b) it is verified by procedure tests that such accessories areso designed that the breaking strength is not less than1,4 times the prescribed breaking load of the chain forwhich they are intended.

5.3 Dimensions and tolerances on dimensions

5.3.1 At least one accessory (of the same type, size andnominal strength) out of 25 is to be checked for dimensionsafter proof load testing. The manufacturer is to provide astatement indicating compliance with the purchaser'srequirements.

5.4 Mechanical tests

5.4.1 Accessories are to be subjected to mechanical testingas described in [2.3] and [2.4]. For individually producedaccessories or accessories produced in small batches, alter-native testing will be subjected to special consideration.

5.5 Non-destructive examination

5.5.1 After proof load testing all chain accessories are to besubjected to a close visual examination. Special attention isto be paid to machined surfaces and high stress regions. Allnon-machined surfaces are to be sand or shot blasted topermit a thorough examination. All accessories are to bechecked by mangnetic particles or dye penetrant.

The manufacturer is to provide a statement that nondestructive examination has been carried out with satisfac-tory results. This statement should include a brief referenceto the techniques and to the operator's qualification.

5.6 Test failures

5.6.1 In the event of a failure of any test the entire batchrepresented is to be rejected unless the cause of failure hasbeen determined and it can be demonstrated to the Sur-veyor's satisfaction that the condition causing the failure isnot present in any of the remaining accessories.

5.7 Marking

5.7.1 Each accessory is to be marked as follows:

chain grade.

The certificate number may be exchanged against an abbre-viation or equivalent. If so, this shall be stated in the certifi-cate.

5.8 Documentation

5.8.1 A complete Inspection and Testing Report in bookletform shall be provided by the manufacturer for each order.This booklet shall include all dimensional checks, test andinspection reports, NDT reports, process records as well asany nonconformity, corrective action and repair work.

Each type of accessory shall be covered by separate certifi-cates.

All accompanying documents, appendices and reports shallcarry reference to the original certificate number.

The manufacturer will be responsible for storing, in a safeand retrievable manner, all documentation produced for aperiod of at least 10 years.

offshore mooring chain cables and accessories

Documents