norsok m-122 (ed. 2012)_cast structural steel

5/21/2018 NORSOK M-122 (Ed. 2012)_Cast Structural Steel

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This NORSOK standard is developed with broad petroleum industry participation by interested parties in theNorwegian petroleum industry and is owned by the Norwegian petroleum industry represented by The NorwegianOil Industry Association and The Federation of Norwegian Industry. Please note that whilst every effort has beenmade to ensure the accuracy of this NORSOK standard, neither The Norwegian Oil Industry Association nor TheFederation of Norwegian Industry or any of their members will assume liability for any use thereof. Standards

Norway is responsible for the administration and publication of this NORSOK standard.

Standards Norway Telephone: + 47 67 83 86 00Strandveien 18, P.O. Box 242 Fax: + 47 67 83 86 01N-1326 Lysaker Email: [email protected] Website: www.standard.no/petroleum

Copyrights reserved

NORSOK STANDARD M-122 Edition 2, October 2012

Cast structural steel

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NORSOK standard M-122 Edition 2, October 2012

NORSOK standard Page 1 of 16

Foreword 2Introduction 21 Scope 32 Normative and informative references 3

2.1 Normative references 32.2 Informative references 3

3 Terms, definitions and abbreviations 43.1 Terms and definitions 43.2 Abbreviations 4

4 Qualification 44.1 General 44.2 Basis for qualification of steel foundries 54.3 General requirements 54.4 Manufacturing 54.5 Qualification based upon a test program 6

4.5.1 General 64.5.2 Qualification of the manufacturing process 64.5.3 Validity of qualification 64.5.4 Selection of material for testing 74.5.5 Extent of testing 74.5.6 Base material 74.5.7 Weldability 74.5.8 Qualification test record 75 Requirement to cast structural steel 8

5.1 Steel making process 85.2 Heat treatment 8

5.2.1 General 85.2.2 Heat treatment procedures 85.2.3 Post weld heat treatment (PWHT) 8

5.3 Chemical composition 85.4 Mechanical testing 9

5.4.1 General 95.4.2 Frequency of testing 105.4.3 Position of test specimens 105.4.4 Test methods 105.4.5 Mechanical properties 10

5.5 Retesting and criteria for rejection 116 Non destructive testing (NDT) 11

6.1 General 116.2 Surface requirements 116.3 Qualification of NDT personnel 116.4 Extent of testing 126.5 Test methods 12

6.5.1 Visual inspection 126.5.2 Magnetic particle testing 12 Pro

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6.5.3 Radiographic testing 126.5.4 Ultrasonic testing 12

6.6 Acceptance criteria 136.6.1 General 136.6.2 Visual examination 146.6.3 Radiographic testing 146.6.4 Ultrasonic testing 146.6.5 Magnetic particle testing 147 Repair 15

7.1 Repair by grinding 157.2 Repair by welding 15

8 Tolerances for dimensions and weight 159 Surface protection 1510 Marking 1611 Certificate 16

Foreword

The NORSOK standards are developed by the Norwegian petroleum industry to ensure adequate safety,value adding and cost effectiveness for petroleum industry developments and operations. Furthermore,NORSOK standards are, as far as possible, intended to replace oil company specifications and serve asreferences in the authorities regulations.

The NORSOK standards are normally based on recognised international standards, adding the provisionsdeemed necessary to fill the broad needs of the Norwegian petroleum industry. Where relevant, NORSOKstandards will be used to provide the Norwegian industry input to the international standardisation process.Subject to development and publication of international standards, the relevant NORSOK standard will bewithdrawn.

The NORSOK standards are developed according to the consensus principle generally applicable for moststandards work and according to established procedures defined in NORSOK A-001.

The NORSOK standards are prepared and published with support by The Norwegian Oil IndustryAssociation (OLF), The Federation of Norwegian Industry, Norwegian Shipowners Association and ThePetroleum Safety Authority Norway.

NORSOK standards are administered and published by Standards Norway.

Introduction

This NORSOK standard is based on former company specifications and experience from deliveries andoperation.


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1 Scope

This NORSOK standard defines the requirements for qualification of foundries and the technical deliveryrequirements for cast structural steel for use in offshore structures where steel quality level I or II is required.

2 Normative and informative references

The following standards include provisions and guidelines which, through reference in this text, constituteprovisions and guidelines of this NORSOK standard. Latest issue of the references shall be used unlessotherwise agreed. Other recognized standards may be used provided it can be shown that they meet therequirements of the referenced standards.

2.1 Normative references

ASME V, Article 5, Ultrasonic Examination Methods For Materials And FabricationASME V, Article 7, Magnetic Particle ExaminationASTM A609, Standard Practice For Castings, Carbon, Low-Alloy And Martensitic Stainless

Steel, Ultrasonic Examination ThereofASTM A991, Standard Test Method for Conducting Temperature Uniformity Surveys of

Furnaces Used to Heat treat Steel products

ASTM E112, Standard Test Method for Determining Average Grain SizeASTM E45, Standard Test Methods for Determining the Inclusion Content of SteelASTM E125 80, Standard Reference Photographs For Magnetic Particle Indications On Ferrous

CastingsASTM E446, Reference Radiographs For Steel Castings Up To 51 mm In ThicknessASTM E186, Reference Radiographs For Heavy-Walled (51 to 112 mm) Steel CastingsASTM E280, Reference Radiographs For Heavy-Walled (112 to 305 mm) Steel CastingsEN 287-1, Qualification test of welders Fusion welding Part 1: SteelsEN 473/Nordtest/ASNT, Qualification of NDT operatorsEN 10204, Metallic products Types of inspection documentsEN 10225, Weldable structural steels for fixed offshore structures Technical delivery

conditionsISO148, Steel Charpy impact test (V-notch)ISO 6892, Metallic material Tensile testing at ambient temperatureISO 8062, Castings System of dimensional tolerances and machining allowancesISO 9001, Quality management systems RequirementsISO 10423, Petroleum and natural gas industries Drilling and production equipment

Wellhead and Christmas tree equipmentISO 15607, Specification and qualification of welding procedures for metallic materials

General rulesISO 15609-1, Specification and qualification of welding procedures for metallic materials

Welding procedure specification Part 1: Arc weldingISO 15614-1, Specification and qualification of welding procedures for metallic materials

Welding procedure test Part 1: Arc and gas welding of steels and arc weldingof nickel and nickel alloys

ISO/IEC 17025, General requirements for the competence of testing and calibration laboratoriesMSS-SP 55, Visual Inspection Guide For Steel CastingsNORSOK M-101, Structural steel fabricationRecommandationTechnique No. 359-01 duBureau de Normalisationdes Industries de laFonderie (BNIF),

2.2 Informative references

None


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3 Terms, definitions and abbreviations

For the purposes of this NORSOK standard, the following terms, definitions and abbreviations apply.

3.1 Terms and definitions

3.1.1can

verbal form used for statements of possibility and capability, whether material, physical or casual

3.1.2mayverbal form used to indicate a course of action permissible within the limits of this NORSOK standard

3.1.3shallverbal form used to indicate requirements strictly to be followed in order to conform to this NORSOKstandard and from which no deviation is permitted, unless accepted by all involved parties

3.1.4should

verbal form used to indicate that among several possibilities one is recommended as particularly suitable,without mentioning or excluding others, or that a certain course of action is preferred but not necessarilyrequired

3.2 Abbreviations

ACCP ASNT Central Certification ProgramAOD argon oxygen decarburisationASME American Society Mechanical Engineers StandardASNT American Society for Non-destructive TestingASTM American Society for Testing and MaterialsBS British StandardCTOD crack tip opening displacementEN European StandardFATT fracture appearance transition temperaturesHAZ heat affected zoneIEC International Electrotechnical CommisssionIIW International Institute of WeldingISO International Organization for StandardizationMT magnetic particle testingNDT non-destructive testingPWHT post weld heat treatmentRT radiographic testingVAD vacuum argon decarburisationVODC vacuum oxygen decarburisation converterUT Ultrasonic testing

4 Qualification

4.1 General

The purchaser may accept the foundrys qualification based on general information described in 4.2-4.4combined with a verification or audit at the foundry.

However, depending on the criticality and complexity of the casting and the experience of the foundry, thepurchaser may require the foundry to perform a qualification as described in 4.5.


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4.2 Basis for qualification of steel foundries

The basis for qualification is as follows:

documented knowledge and previous experience with the material and the manufacturing;

manufacturing facilities and equipment;

established manufacturing procedures covering all important manufacturing steps from melting tofinished products;

manufacturers quality system, which shall fulfill the requirements related to product realization inISO 9001;

results of testing in compliance with this NORSOK standard.

Prior to qualification a complete report, with information and results of testing as required by this standardshall be available for review.

4.3 General requirements

The manufacturer shall have knowledge and experience within relevant metallurgical aspects of theapplicable steel grades including welding, heat treatment parameters, etc. as applicable for hismanufacturing process.

Experience should be supported by statistical data or relevant test records for the size range to be qualified.The steel shall have beenproduced to manufacturing procedures and with equipment intended used for theactual manufacturing.

Facilities and equipment shall be fit for purpose, regularly maintained and calibrated as required. Theassessment shall concentrate on facilities and equipment for moulding, melting, refining, welding, heattreatment, etc.

Foundries shall have heat treatment facilities on their own premises or such facilities shall be located in theirclose vicinity.

If parts of the production are carried out at a sub-supplier, the manufacturer is responsible for ensuring thatthe sub-supplier meets the requirements of this standard for the manufacturing steps that he is performing.

4.4 Manufacturing

The manufacturer shall have a Manufacturing Summary for each production route. The ManufacturingSummary shall describe, step by step in a logical and correct sequence all important manufacturing activitieswith reference to detailed procedures. A short description and the main parameters for each activity shall beincluded. The production route shall be illustrated with a flow chart. The scope of the manufacturingsummary shall be clearly defined:

name and address of manufacturer;

grade of material;

type and size range of products for which the manufacturing summary applies;

identification of the manufacturing process.

The manufacturing summary shall include procedures for

moulding method, type of sand, binding agent and method of casting,

melting and refining processes,

heat treatment, including

loading temperature, heating rate, holding temperature (range) and time,

loading and stacking of components in furnace,

type and identification of furnace(s),

maximum operation temperature for furnace(s),

temperature control and calibration of furnace(s),

cooling facilities and max. time from furnace to quenching bath (if relevant),

sketch of heat treatment facilities/furnace which also shall show location of pyrometers and/orthermocouples in the furnace(s) and on the component(s).


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blasting/cleaning equipment, incl. type of grit,

repair welding,

PWHT (if applicable),

NDT and inspection,

material testing. Type of tests and test sampling,

design and position of test coupons.

If the manufacturer has different plants or different production routes for a product, separate documentationis required for each of these. If essential parts of the work such as e.g. heat treatment are subcontracted,this shall be identified in the documentation.

Whenever a change is made in the equipment or procedures, the documentation shall be updatedaccordingly.

The casting shall not be subject to any plastic deformation during manufacturing including handling at hightemperatures.

4.5 Qualification based upon a test program

4.5.1 GeneralFor critical structural castings or castings intended for welding, base material and weldability data shall berequired documented according to 4.5.2 to 4.5.8.

4.5.2 Qualification of the manufacturing process

The manufacturing process as described in the manufacturing summary shall be qualified by testing ofactual products or of test blocks, if accepted by the purchaser, to

demonstrate that the proposed manufacturing route and production parameters results in productsmeeting specified requirements,

verify that the proposed production test sampling gives results which are representative of the propertiesin the actual components which they represent.

4.5.3 Validity of qualification

4.5.3.1 General

The qualification shall be repeated if there are changes in the production route, the manufacturingprocedures or the specified composition or properties of the products which exceeds the limits given below.

4.5.3.2 Plant and location

If production is carried out at different plants/locations, a separate qualification is required for each plant.This applies also for change of subcontractors for essential operations as e.g. heat treatment, etc.

4.5.3.3 Thickness limitations

The maximum thickness qualified is the thickness of the tested product or test block plus 25 %.

4.5.3.4 Material grade

A change from one steel grade to a higher grade requires requalification.

4.5.3.5 Type of melting and refining equipment

A change of the melting/refining process requires a requalification.

4.5.3.6 Manufacturing equipment

A major change of manufacturing equipment requires requalification, unless the new equipment can beregarded as comparable to the old one with respect to its influence on the product properties. This appliesalso if the manufacturer has several alternative manufacturing routes for a product.


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4.5.3.7 Heat treatment

A change of heat treatment method, (e.g. a change from normalising to quenching and tempering) willrequire requalification. This also includes change in PWHT operations, when applicable.

4.5.4 Selection of material for testing

Selection of components or test blocks for testing and positioning of test samples shall be agreed betweenpurchaser and the manufacturer.

4.5.5 Extent of testing

Testing for qualification shall comprise

production testing with test sampling as specified in this NORSOK standard,

additional testing for qualification as required by this NORSOK standard,

non-destructive testing as specified in this NORSOK standard.

4.5.6 Base material

4.5.6.1 General

The material used for the examinations to document properties shall be representative, implying that thesteel making process, casting methods and heat treatment condition shall be equal to that proposed for theactual delivery. The section thicknesses shall be representative for the thinnest and thickest portion in thecasting for the actual delivery.

4.5.6.2 Chemical composition and mechanical properties

The chemical composition and mechanical properties shall be as per clause 5.

4.5.6.3 Charpy V-notch impact test transition curves

Charpy V-notch impact test transition curves ( 80 C, 60 C, 40 C and 20 C) shall be made for boththe thinnest and thickest material section. The position and number of the test specimens shall be asspecified in 5.4.3. Both the energy absorption (J) and the FATT, defined as 50 % crystallinity, shall bereported.

4.5.6.4 Micrographic examinations

The base material microstructure shall be documented by micrographs at magnification 500 X fromsubsurface, 1/4 thickness and 1/2 thickness position. The type of structure, grain size and inclusion levelshall be reported. Examination shall be carried out according to ASTM E112 and ASTM E45.

4.5.7 Weldability

Weldability data are required for castings with a weld bevel thickness above 25 mm. The thickness to beused for the weldability test shall be agreed, but shall not to less than 10 % below the weld bevel thicknessto be delivered The documentation of the weldability shall be in accordance with EN 10225, Annex E.

The heat input shall be 3,5 0,2 kJ/mm (EN 10225, Table E.3).

For weld bevel thicknesses above 50 mm the testing shall be carried out both in the as welded and PWHTcondition.

CTOD testing is required for weld bevel thickness above 50 mm and shall meet a requirement of minimum0,25 mm (as-welded) and 0,20 mm (PWHT), at 10 C unless a lower value has been accepted by thepurchaser. CTOD testing is limited to only grain-coarsened HAZ.

4.5.8 Qualification test record

The manufacturer shall present a qualification test record containing results of all required tests as well asdetails about test sampling and test procedures.


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5 Requirement to cast structural steel

5.1 Steel making process

The steel shall be made by basic oxygen or electric arc furnace process and shall be fully killed and finegrain treated. A further treatment by ladle desulphurization and secondary refining using AOD/ VODC/ VADor equal, shall be performed to secure a base material with very close controlled chemistry and low levels ofelements like phosphorous, sulphur, oxygen and hydrogen.

5.2 Heat treatment

5.2.1 General

All castings shall be delivered in homogenised, normalised and stress relieved condition, or in homogenised,quenched and tempered condition, also including any post weld heat treatment after repair welding.

5.2.2 Heat treatment procedures

All heat treatments shall be carried out according to an accepted procedure containing at least the followinginformation:

description of furnaces and quenching facilities; location and support of the castings in the furnace;

locations and number of thermocouples;

all temperature cycles.

The heat treatment variables shall be selected to promote uniform microstructure, correct mechanicalproperties for the different section thicknesses and to reduce residual stresses.

Heat treatment temperatures shall be measured and recorded by means of thermocouples attached to thecastings.The temperature in the furnace at the time of loading the castings shall not exceed 200 C. The heating andcooling rates for temperatures above 300 C shall not exceed 70 C and 50 C per hour respectively exceptfor quenching. Below 300 C the castings may be cooled in still air.

The heat treatment furnaces shall be calibrated according to ASTM A991 or ISO 10423, Annex M.

5.2.3 Post weld heat treatment (PWHT)

PWHT shall be carried out after any repair welding. All PWHT shall be carried out in a closed furnace. Thesoaking temperature shall be as qualified during the repair welding procedure. The soaking time shall beminimum 2 min/mm of the thickest wall at the actual weld repair location.

5.3 Chemical composition

Chemical composition for the three cast steel grades are given in Table 1. The values apply to both ladleand product analysis. Any modification from Table 1 shall be agreed in each case. Ladle analysis shall beperformed for each heat and product analysis performed for each casting.


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Table 1 Chemical composition

Steel Grade 310 420 460C 0,14 0,14 0,14Si 0,60 0,60 0,50Mn 1,60 1,60 1,60

S 0,008 0,008 0,005P 0,012 0,012 0,012Cr 0,20 0,25 1,3Ni 1,10 1,10 2,7Mo 0,08 0,30 0,55Al 0,05 0,05 0,05N 0,010 0,010 0,010Cu 0,25 0,25 0,25Nb

b) 0,03 0,03 0,03

Vb)

0,05 0,05 0,05Ti 0,04 0,04 0,04Sb 0,01 0,01 0,01Sn 0,015 0,015 0,015

Pb 0,005 0,005 0,005As 0,02 0,02 0,02Bi 0.005 0,005 0,005B 0,0010 0,0010 0,0010Pcm

a) 0,24 0,26 0,28

CEa)

0,41 0,48 0,55

All values are maximum values unless a range is given, all in weight percent.

a)

5B10

V

15

Mo

60

Ni

20

CrCuMn

30

SiCPcm

15

CuNi

5

VMoCr

6

MnCCE

b)

0,05%VNb

5.4 Mechanical testing

5.4.1 General

All mechanical testing shall be carried out in the final delivery condition (including PWHT).

The test blocksshall not be removed from the castings until all quality heat treatments have been carriedout. It is acceptable that the test blocks are given a simulated PWHT.

All mechanical testing for certification shall be performed by a laboratory that complies with ISO/IEC 17025or an accredited laboratory


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5.4.2 Frequency of testing

Product testing shall be carried out for each cast item. Other frequencies of mechanical testing might beagreed with the purchaser in case of large series of castings or weight less than 1 ton.

The number of test blocks shall be:

A. Integral test block(s):

Weight of castings G (tonnes) Number of test block(s)

G < 2 * 1

2 G < 10 2

10 G < 20 3

G 20 minimum 4

*Minimum 1 off integral test block for each casting.

The test block(s) shall be an integral part of the casting. The test block(s) shall not be gated onto the casting.

The thickness of the integral test block(s) shall represent the maximum weld member end thickness and/or

critical thickness to ensure representative microstructure and mechanical properties.

The location (sketch) and size of the integral test block(s) shall be agreed with the purchaser prior to start ofproduction. If there are more than one test sample on a casting, the blocks shall be located as far away fromeach other as possible.

B. Separate cast test block(s):

Two separately cast test blocks shall be cast per heat/heat treatment batch with equivalent thickness to themaximum casting section in the heat treatment batch (up to a limit of 500 mm).

5.4.3 Position of test specimens

1 tensile test and 3 Charpy V-notch tests shall be carried out from each of the three following positions of the

test blocks:

Thin section: 50 mm - Mid thickness (T/2)Thick section: > 50 mm - Sub surface (2 mm below surface) and T/3

5.4.4 Test methods

The tensile testing shall be carried out according to ISO 6892.

The Charpy V-notch testing shall be carried out according to ISO 148. The longitudinal axis of the specimenshall be parallel to the cast surface with the notch perpendicular to the same.

5.4.5 Mechanical properties

Requirements for mechanical properties are given in Table 2.

Table 2 Mechanical properties

Steelgrade

YieldstrengthRemin*

MPa

TensilestrengthRmmin

MPa

ElongationA5min

%

Reductionof areaZ min

%

Impact testKV min

Javerage/single

KVtest

temp.oC

RatioRe/Rm

maximum

310 310 450 20 50 36/27 40 0,85

420 420 540 20 40 42/35 40 0,90

460 460 560 18 40 42/35 40 0,90

For section thicknesses above 100 mm, lower values for Reand Rmmay be agreed.

* Re= ReHor Rp0,2


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5.5 Retesting and criteria for rejection

If one or more of the results fails to meet the requirements, the manufacturer may carry out double set ofadditional tests, preferably from the same test coupon and position. All results from retest shall meet therequirements.

If retesting fails, the casting will be rejected. However the manufacturer may choose to carry out a reheattreatment once followed by full set of mechanical testing. If any results still are not acceptable, the casting or

lot will be rejected.

6 Non destructive testing (NDT)

6.1 General

All NDT shall be carried out in accordance with the established procedures.

The NDT reports shall show examined areas, size and nature of defects and reportable indications.

6.2 Surface requirements

All surfaces shall be free from irregularities which may interfere with the performance of the examinations.

The surface of the castings shall be examined visually and shall be free of adhering sand, scale, cracks andhot tears.Other surface discontinuities shall meet the requirements specified for MT.

Surface roughness shall as a minimum be as follows (see Recommandation Technique No. 359-01 duBureau de Normalisation des Industries de la Fonderie (BNIF)):

4S1 on surfaces subject to UT with normal probes;

3S2 on surfaces subject to UT with angle probes;

3S2 on transition zones/fillets surfaces subject to MT;

4S1 on general surfaces subject to MT and Visual inspection;

3S1 on surfaces subject to RT only.

When surfaces are machined the roughness shall as a minimum be as follows (see BS 2634-1):

Ra 12 m on surfaces subject UT with normal probes;

Ra 6 m on surfaces subject UT with angel probes;

Ra 12 m on general surfaces subject to MT and visual inspection.

6.3 Qualification of NDT personnel

All NDT personnel shall be qualified according to EN 473/Nordtest level II in product sector (c) or an industrysector containing product sector (c) ASNT ACCP level 2 accredited NDT. Personnel performing RTexposures only, may, however, be qualified to level I.

Personnel qualified to level III, shall be responsible for all NDT activities. ASNT-TC-1A level III personnelshall hold valid ASNT-TC-1A level III Certificate (i.e. Management appointed level III is not accepted).

Contractor shall keep an updated list of all NDT personnel engaged in the work, with reference to possessedcertificates and expiry dates. This list shall be made available to Purchaser on request.


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6.4 Extent of testing

The extent of NDT shall be as per Table 3.

Table 3 - Extent of NDT

Methods Areas and volume to beexamined

Extent ofNDT

%

ime for examinationNOTE 1

Visualexaminations

Surface from inside and outside. 100 F

Magnetic particletesting

Surface from inside and outside.Excavated grooves before start

of repair welding.

100

100

F

Radiographictesting

Weld end zones.Area 3 x thickness of the edge,

or minimum 100 mm

100NOTE 2

Questionable indicationsdetected by ultrasonic testing

100

Ultrasonic testing Normal probes. Volumetric

testing (from all accessibleinside and outside

100

Angle probes. Areas where theangles between front and backsurfaces of the casting exceed

15(non-parallel)

100

Angle probes. Areas where lossof back wall echo occurs.

100

Angle probes. Indications fromthe testing with normal probes.

100

Repaired areas where thedefects were detected by

radiography or ultrasonic testing.

100 F

NOTE 1 F means that the NDT shall be carried out in the final repair welded and PWHTcondition. Otherwise, the NDT may be carried out before the final repair weldingand PWHT.

NOTE 2 100 % radiography of weld end zones may be deleted provided ultrasonic testing(UT) is carried out in accordance with NORSOK M-101 and the acceptancecriteria as specified in 9.8/Table 5 Inspection Category A+B.

6.5 Test methods

6.5.1 Visual inspection

Visual inspection shall be in accordance with MSS SP-55

6.5.2 Magnetic particle testing

Magnetic particle testing shall be carried out according to ASME Section V, Article 7. An NDT procedureshall be prepared. The procedure shall show the acceptance criteria.

6.5.3 Radiographic testing

Radiographic testing shall be carried out in accordance with ASME Section V, Article 2. A written procedureshall be prepared as specified in T-221.1.

6.5.4 Ultrasonic testing

6.5.4.1 Procedures

Ultrasonic testing shall be carried out in accordance with ASME Section V, Article 5, using normal probesand angle probes.


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6.5.4.2 Procedures

The ultrasonic testing procedures shall additionally include at least the following information:

sensitivity setting;

typical sketches of section (with dimensions) to be examined which clearly show scanning pattern andprobes to be used;

acceptance criteria;

reporting and identification system.

6.5.4.3 Probes

The frequency value shall be selected to suit the test and shall be within the range 0.5 MHz to 5 MHz. Higherfrequency can be used for testing wall thicknesses of less than 20 mm or areas close to the surface. For thedetection of near-surface discontinuities, the use of dual-element and/or angle probes shall be used.

The probes for ultrasonic testing shall be selected in accordance with Table 4.

Table 4- Probes for ultrasonic testing

Section

thickness

Normal probes Angle probes

< 100 mm 4 MHz, crystal sizediameter 10 mm to 24 mm

2 Mhz to 4 Mhz, 45to 70crystalsize, approximately 8 mm x 9 mm

> 100 mm 2 Mhz, crystal sizediameter 10 mm to 24 mm

2 Mhz to 4 MHz, 45to 70crystalsize, approximately 20 mm x 22 mm

NOTE 1 Crystal size shall be selected to give optimum coverage and coupling to testsurface.

NOTE 2 Twin crystal probes shall be used for evaluation of indications close to thesurface.

NOTE 3 All available probes shall be used for assessment of indications.

6.5.4.4 Calibration blocksThe flat bottom holes in the reference blocks in ASTM A609, Figure 1, shall have a diameter equal to 3 mmfor sensitivity setting for normal probes.

One additional reference block is required having metal distance equal to 10 mm for assessment ofindications close to the surface.

6.5.4.5 Ultrasonic attenuation

The ultrasonic attenuation in the casting shall be checked at different typical locations of the casting. Thedifference in attenuation shall be taken into consideration during the testing.

6.6 Acceptance criteria

6.6.1 General

Contractor shall review the defined acceptance criteria in 6.6.2, 6.6.3 and 6.6.4 and secure that these meetthe design requirements for the cast steel materials. Manufacturer shall be informed if more stringentacceptance criteria have to be applied. Revised acceptance criteria shall be implemented on drawings, NDTprocedures and NDT reports.

The castings are divided in Zone 1, 2 and 3 as follows, unless otherwise shown on drawings:

Zone 1: 0 mm to 30 mm from all finished surfaces and all critical zones independent of thicknessZone 2: Depths greater than 30 mm from all finished surfaces.Zone 3: Weld end zones: Full thickness of end (preparation) for a distance of 3T or minimum 100 mm

from the (preparation) end.


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6.6.2 Visual examination

All surfaces shall show evidence of good workmanship and satisfy the following:

surface requirements as per 6.2;

visual appearance shall also satisfy 6.6.5;

MSS-SP-055.

6.6.3 Radiographic testing

Acceptance criteria related to type of discontinuity and zones are given in Table 5

Table 5 Acceptance criteria for radiographic testing

Zone Type ofdiscontinuity

Acceptance standard

1 Cracks Not acceptable

Gas porosity ASTM E186, ASTM E280, ASTM E446, level A2

Inclusions ASTM E186, ASTM E280, ASTM E446, level B2

Shrinkage ASTM E186, ASTM E280, ASTM E446, level C2


Gas porosity ASTM E186, ASTM E280, ASTM E446, level A4Inclusions ASTM E186, ASTM E280, ASTM E446, level B4

Shrinkage ASTM E186, ASTM E280, ASTM E446, level C4


Gas porosity Shall meet the requirements of NORSOK M 101:Inspection category A + B Section 9.8, Table 6.Shrinkage: ASTM E186, ASTM E280, ASTM E446,level C1

Inclusions

Shrinkage

6.6.4 Ultrasonic testing

Acceptance criteria for ultrasonic testing are given below:

Zone 1 ASTM A609, Table 2 - Level 1 Linear indications are not acceptable.

Zone 2 ASTM A609, Table 2 - Level 3 Linear indications are not acceptable.

Zone 3 Indications shall meet the requirements of NORSOK M 101 - Inspection category A + B Table 7.

6.6.5 Magnetic particle testing

Acceptance criteria for magnetic particle testing are given in Table 6

Table 6 Acceptance criteria formagnetic particle testing

Type of indications Acceptance standard

linear not acceptable

shrinkage ASTM E125, level 2

inclusions ASTM E125, level 3

chills and chaplets ASTM E125, level 1

porosity ASTM E125, level 1


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7 Repair

7.1 Repair by grinding

Repair by arc gouging and grinding may be carried out to a depth of maximum 10 % of the wall thickness (atthe location of the defect) or maximum 15 mm, whichever is less. It is a provision that the design wallthickness is maintained. Arc-air gouged areas shall be ground. The ground area shall be 100 % magneticparticle tested to ensure complete elimination of the defective material. All grinding shall be carried out in away that ensures smooth transitions.

7.2 Repair by welding

Defects shall be repaired by welding if they are deeper than 15 mm or 10 % of the wall thickness. All repairwelds shall be recorded.

The maximum extent of repair welding shall not exceed 20 % of the total surface area unless otherwiseagreed with the purchaser.

The excavations shall be suitably shaped to allow good access for welding. The groove shall be groundsmooth and be free from dirt, grease, oil, etc.

Welding consumable of low hydrogen content (maximum 5 ml/HDMpr. 100 g, IIW-method) shall be used forrepair welding. The welding consumable shall be handled according to the consumable manufacturer'srecommendations.

Repair welding procedures shall be established and qualified according to ISO 15607, ISO 15609-1 andISO 15614-1, with the following additional requirements. The repair welding procedure shall be qualified onthe same grade of material as the delivered component:

Charpy V-notch impact tests with notch locations in weld metal, fusion line and heat affected zone+ 2 mm and + 5 mm from fusion line, respectively. Test results shall meet the requirements specified forthe parent metal;

macro section;

hardness values shall not exceed 350 HV10.

Welders shall be qualified according to EN 287-1.

Castings repaired by welding shall be post weld heat treated at a temperature at least 15 C below thetempering temperature. On completion of heat treatment the weld repairs and adjacent material shall beground smooth. All weld repairs shall be magnetic particle tested and major repairs shall additionally beultrasonic (or radiographic) tested. Weld repairs shall meet the quality level designated for that particularzone of the casting.

The foundry shall maintain records of repair welding, subsequent heat treatment and inspections traceableto each casting repaired.

8 Tolerances for dimensions and weight

Dimensions and required tolerances shall be as given on the relevant drawing of the casting or otherinformation supplied. If nothing is specified, ISO 8062, Grade CT, 13 shall apply.

The weight tolerances shall be within agreement with the purchaser.

9 Surface protection

Castings shall before delivery, be degreased, shot blasted to bright metal and protected by a shop primerwith a dry film thickness of approximately 20 m.All sharp edges shall be rounded and smoothed bygrinding to a minimum radius of 2 mm to assure full film thickness on all edges.

Machined surfaces shall be protected by a rust protection coating (water soluble Tectyl or equivalent).


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10 Marking

Castings shall be marked for identification against a certificate. The marking shall include Contractorsidentification and heat number.

All markings shall be carried out by die stamping or as cast in marks, and be framed by white painting. Theletters used for the stamping should be 15 mm in height.

11 Certificate

Certificate according to 3.1 (see EN 10204) is required.

The certificate shall contain all relevant information including, but not restricted to the following:

purchasers name and order number;

delivery condition;

heat number/casting number;

description of product, dimension and weight;

yield strength, tensile strength, elongation and reduction of area;

Charpy V-notch values and test temperature;

chemical composition, carbon equivalent/Pcm; visual inspection and NDT, or reference to separate reports;

weld repairs, or reference to separate reports.


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norsok m-122 (ed. 2012)_cast structural steel

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