This NORSOK standard is developed by NTS with broad industry participation. Please note that whilst every effort
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NORSOK STANDARD
M-122
Rev. 1, June 2003
Cast structural steel
NORSOK standard M-122
Rev. 1, June 2003
NORSOK standard
Page 1 of 15
Foreword
2
Introduction
2
1
Scope
3
2
Normative references
3
3
Abbreviations
3
4
Qualification
4
4.1
General
4
4.2
Qualification based upon a test program
5
5
Requirement to cast structural steel
7
5.1
Steel making process
7
5.2
Heat treatment
7
5.3
Chemical composition
7
5.4
Mechanical testing
8
5.5
Retesting and criteria for rejection
9
6
Non – destructive testing
9
6.1
General
9
6.2
Surface requirements
9
6.3
Qualification of NDT personnel
10
6.4
Extent of testing
10
6.5
Test methods
11
6.6
Acceptance criteria
12
7
Repair
13
7.1
Repair by grinding
13
7.2
Repair by welding
13
8
Dimensions/tolerances 14
9
Surface protection
14
10
Marking
14
11
Certificate
15
NORSOK standard M-122
Rev. 1, June 2003
NORSOK standard
Page 2 of 15
Foreword
The NORSOK standards are developed by the Norwegian petroleum industry to ensure adequate safety,
value adding and cost effectiveness for existing and future petroleum industry developments.
The NORSOK standards are prepared to complement available international standards and fill the broad
needs of the Norwegian petroleum industry. Where relevant NORSOK standards 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publication of international standards, the relevant NORSOK standard will be withdrawn.
These standards are developed according to the consensus principle generally applicable for most
standards work and according to established procedures defined in NORSOK A-001
The preparation and publication of the NORSOK standards is supported by OLF (The Norwegian Oil
Industry Association) and TBL (Federation of Norwegian Manufacturing Industries). NORSOK standards are
administered and issued by NTS (Norwegian Technology Centre).
Introduction
This standard is based on former company specifications and experience from deliveries and operation.
NORSOK standard M-122
Rev. 1, June 2003
NORSOK standard
Page 3 of 15
1 Scope
This Standard defines the requirements for qualification of foundries and the technical delivery requirements
for cast structural steel for use in offshore structures where Steel Quality Level I or II is required.
2 Normative
references
The following standards include provisions which, through reference in this text, constitute provisions of this
NORSOK standard. Latest issue of the references shall be used unless otherwise agreed. Other recognised
standards may be used provided it can be shown that they meet or exceed the requirements of the
standards referenced below.
ASME V Article 3
Radiographic Examination
ASME V, Article 5
Ultrasonic Examination Methods For Materials And Fabrication
ASME V, Article 7
Magnetic Particle Examination
ASME IX
Welding and Brazing Qualifications
ASTM A 609
Standard Practice For Castings, Carbon, Low-Alloy And Martensitic Stainless
Steel, Ultrasonic Examination Thereof
ASTM E 112
Standard Test Method for Determining Average Grain Size
ASTM E 125 - 80
Standard Reference Photographs For Magnetic Particle Indications On Ferrous
Castings
ASTM E 446
Reference Radiographs For Steel Castings Up To 51 mm In Thickness
ASTM E 186
Reference Radiographs For Heavy-Walled (51 to 112 mm) Steel Castings
ASTM E 280
Reference Radiographs For Heavy-Walled (112 to 305 mm) Steel Castings
ASTM E 709
Standard Practice For Magnetic Particle Examination
BS 7448
Fracture mechanics toughness tests
Bureau de Normalisation
des Industries de la
Fondrie (BNIF)
Technical Recommendation No. 341-02, "Characterisation Of Surface Condition
Of Steel Castings"
EN 287
Approval testing of welders – Fusion welding
EN 288
Specification and approval of welding procedures for metallic materials
EN 473/Nordtest/ASNT
Qualification of NDT operators
EN 10204
Metallic products – Types of inspection documents
ISO148
Steel – Charpy impact test (V-notch)
ISO 2632 / III
Roughness Comparison Specimens, Cast Surfaces
ISO 6892
Metallic material – Tensile testing at ambient temperature
ISO 8062
Castings – System of dimensional tolerances and machining allowances
ISO 9001
Quality management systems – Requirements
MSS-SP 55
Visual Inspection Guide For Steel Castings
EN 10225 (Aug. 2001)
Weldable structural steels for fixed offshore structures – Technical delivery
conditions
3 Abbreviations
AOD
Argon Oxygen Decarburisation
CTOD Crack
Tip
Opening
Displacement
FATT
Fracture Appearance Transition Temperatures
NDT
Non Destructive Testing
PWHT
Post Weld Heat Treatment
VODC
Vacuum Oxygen Decarburisation Converter
VAD
Vacuum Argon Decarburisation
NORSOK standard M-122
Rev. 1, June 2003
NORSOK standard
Page 4 of 15
4 Qualification
The purchaser may accept the foundry’s qualification based on general information described in 4.1
combined with a verification or audit at the foundry.
However, depending on the criticality and complexity of the casting and the experience of the foundry, the
purchaser may require the foundry to perform a qualification as described in 4.2.
4.1 General
4.1.1 Basis
for
qualification of steel foundries
The basis for qualification:
•
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 to
finished products.
•
Manufacturers quality system, which shall fulfil the requirements related to product realization in ISO
9001 or equivalent.
•
Results of testing in compliance with this standard.
Prior to qualification a complete report, with information and results of testing as required by this standard
shall be available for review.
4.1.2 General
requirements
The manufacturer shall have knowledge and experience within relevant metallurgical aspects of the
applicable steel grades including welding, heat treatment parameters, etc. as applicable for his
manufacturing process.
Experience should be supported by statistical data or relevant test records for the size range to be qualified.
The steel shall have been produced to manufacturing procedures and with equipment intended used for the
actual manufacturing.
Facilities and equipment shall be fit for purpose, regularly maintained and calibrated as required. The
assessment shall concentrate on facilities and equipment for moulding, melting, refining, welding, heat
treatment, etc.
Foundries shall have heat treatment facilities on their own premises or such facilities shall be located in their
close vicinity.
If parts of the production is carried out at a sub-supplier, the manufacturer is responsible for ensuring that
the sub-supplier meets the requirements of this standard for the manufacturing steps that he is performing.
4.1.3 Manufacturing
The manufacturer shall have a Manufacturing Summary for each production route. The Manufacturing
Summary shall describe, step by step in a logical and correct sequence all important manufacturing activities
with reference to detailed procedures. A short description and the main parameters for each activity shall be
included. The production route shall be illustrated with a flow chart. The scope of the manufacturing
summary shall be clearly defined:
•
Name and address of manufacturer.
•
Grade of material with reference to standard.
•
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.
NORSOK standard M-122
Rev. 1, June 2003
NORSOK standard
Page 5 of 15
•
Melting and refining processes.
•
Heat treatment, including:
•
Loading temperature, heating rate, holding temperature (range) and time.
•
Loading of components in furnace.
•
Type
of
furnace(s).
•
Max. operating 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/or
thermocouples in the furnace.
•
Blasting/cleaning equipment, incl. type of grit.
•
Repair
welding.
•
PWHT (if applicable).
•
NDT and inspection.
•
Material testing. Type of tests and time of test sampling.
•
Design and position of test coupons.
If the manufacturer has different plants or different production routes for a product, separate documentation
is required for each of these. If essential parts of the work such as e.g. heat treatment is subcontracted, this
shall be identified in the documentation.
Whenever a change is made in the equipment or procedures, the documentation shall be updated
accordingly.
4.2
Qualification based upon a test program
For critical structural castings or castings intended for welding, base material and weldability data shall be
required documented according to 4.2.1 – 4-2 7.
4.2.1 Qualification
of
the manufacturing process
The manufacturing process as described in the Manufacturing Summary shall be qualified by testing of
actual products or of test blocks, if accepted by the purchaser, to:
a) Demonstrate that the proposed manufacturing route and production parameters results in products
meeting specified requirements.
b) Verify that the proposed production test sampling gives results which are representative of the properties
in the actual components which they represent.
4.2.2
Validity of qualification
The qualification shall be repeated if there are changes in the production route, the manufacturing
procedures or the specified composition or properties of the products which exceeds the limits given below.
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.
4.2.2.1 Thickness
limitations
The maximum thickness qualified is the thickness of the tested product or test block plus 25 %.
4.2.2.2 Material
grade
A change from one steel grade to a higher grade requires requalification.
4.2.2.3 Type of melting and refining equipment
A change of the melting/refining process requires a requalification.
4.2.2.4 Manufacturing
equipment
A major change of manufacturing equipment requires requalification, unless the new equipment can be
regarded as comparable to the old one with respect to its influence on the product properties. This applies
also if the manufacturer has several alternative manufacturing routes for a product.
NORSOK standard M-122
Rev. 1, June 2003
NORSOK standard
Page 6 of 15
4.2.2.5 Heat
treatment
A change of heat treatment method, (e.g. a change from normalising to quenching and tempering) will
require requalification. This also includes change in PWHT operations, when applicable.
4.2.3
Selection of material for testing
Selection of components or test blocks for testing and positioning of test samples shall be agreed between
purchaser and the manufacturer.
4.2.4
Extent of testing
Testing for qualification shall comprise:
a) Production testing with test sampling as specified in this standard.
b) Additional testing for qualification as required by this standard.
c) Non-destructive testing as specified in this standard
4.2.5 Base
material
The material used for the examinations to document properties shall be representative, implying that:
•
The chemical composition and mechanical properties shall be within the guaranteed limits
•
The steel making process, casting methods and heat treatment condition shall be equal to that proposed
for the actual delivery
The tested section thickness shall be representative for the thinnest and thickest portion in the casting for the
actual delivery.
4.2.5.1 Chemical
composition and mechanical properties
The chemical composition and mechanical properties shall be as per section 5 and 6.
4.2.5.2 Charpy V-notch impact test transition curves
Charpy V-notch impact test transition curves (-80, -60, -40 and –20°C) shall be made for both the thinnest
and thickest material section. The specimen shall be taken from 2 mm below surface and 1/3-thickness
position. Three specimens shall be tested at each test condition.
Both the energy absorption (J) and the FATT (Fracture Appearance Transition Temperatures), defined as
50% crystallinity, shall be reported.
4.2.5.3 Micrographic
examinations
The base material microstructure shall be documented by micrographs at magnification 500 X from
subsurface, 1/4 thickness and 1/2 thickness position. The type of structure, grain size and inclusion level
shall be reported. Testing to be carried out according to ASTM E 112.
4.2.6 Weldability
Weldability data are required for castings with a weld bevel thickness above 25 mm. The thickness to be
used for the weldability test shall be agreed, but is not to be more than 10% below the weld bevel thicknes to
be delivered The documentation of the weldability shall be in accordance with EN 10225 (Aug 2001), 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 PWHT
condition.
CTOD testing is required for weld bevel thickness above 50 mm and shall meet a requirement of minimum
0.25 mm (as-welded) and 0.20 mm (PWHT), at – 10
°
C unless a lower value has been accepted by the
purchaser. CTOD testing is limited to only grain-coarsened HAZ.
4.2.7 Qalification
test
record
The manufacturer shall present a qualification test record containing results of all required tests as well as
details about test sampling and test procedures.
NORSOK standard M-122
Rev. 1, June 2003
NORSOK standard
Page 7 of 15
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 fine
grain treated. A further treatment by ladle desulphurization and secondary refining using AOD/ VODC/ VAD
or equal, shall be performed to secure a base material with very close controlled chemistry and low levels of
elements 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 following
information:
•
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 mechanical
properties for the different section thicknesses and to reduce residual stresses. Heat treatment temperatures
shall be measured and recorded by means of thermocouples attached to the castings.
The temperature in the furnace at the time of loading the castings shall not exceed 200°C. The heating and
cooling rates for temperatures above 300°C shall not exceed 70°C and 50°C per hour respectively except for
quenching. Below 300°C the castings may be cooled in still air.
5.2.3
Post Weld Heat Treatment (PWHT)
PWHT shall be carried out after repair welding. All PWHT shall be carried out in a closed furnace. The
soaking temperature shall be as qualified during the repair welding procedure. The soaking time shall be
minimum 2 min./mm of the thickest wall at the actual weld repair location.
5.3 Chemical
composition
Proposed chemical compositions for the three cast steel grades are given in table 1. The values apply to
both ladle and product analysis. Deviations from this proposal shall be agreed in each case. Ladle analysis
shall be performed for each heat and product analysis performed for each casting.
NORSOK standard M-122
Rev. 1, June 2003
NORSOK standard
Page 8 of 15
Table 1 – Chemical composition
Steel
Grade
310 420 460
C
0,14 0,14 0,14
Si
0,60 0,60 0,50
Mn
1,60 1,60 1,60
S 0,008
0,008
0,005
P 0,012
0,012
0,012
Cr
0,20 0,25 1,3
Ni
1,10 1,10 2,7
Mo
0,08 0,30 0,55
Al
0,05 0,05 0,05
N 0,010
0,010
0,010
Cu
0,25 0,25 0,25
Nb
b)
0,03 0,03 0,03
V
b)
0,05 0,05 0,05
Ti
0,04 0,04 0,04
Sn 0,015
0,015
0,015
B
0,0010 0,0010 0,0010
Pcm
a)
0,24 0,26 0,28
CE
a)
0,41 0,48 0,55
All values are maximum values unless a range is given, all in weight percent.
a)
5B
10
V
15
Mo
60
Ni
20
Cr
Cu
Mn
30
Si
C
Pcm
+
+
+
+
+
+
+
+
=
15
Cu
Ni
5
V
Mo
Cr
6
Mn
C
CE
+
+
+
+
+
+
=
b)
0,05%
V
Nb
<
+
5.4 Mechanical
testing
5.4.1 General
All mechanical testing for certification shall be performed by an accredited laboratory or a laboratory
accepted by the purchaser
5.4.2
Frequency of testing
Product testing shall be carried out for each cast item. Other frequencies of mechanical testing might be
agreed with the purchaser in case of large series of castings or weight less than 1 ton. The test coupons
shall not be removed from the castings until all quality heat treatments have been carried out.
The number of test samples shall be:
A. Integral Test Samples:
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 thickness of the integral test sample shall represent the maximum weld member end thickness and/or
critical thickness to ensure representative microstructure and mechanical properties.
NORSOK standard M-122
Rev. 1, June 2003
NORSOK standard
Page 9 of 15
The purchaser shall approve the location (sketch) and size of the integral test sample(s) prior to start of
production. If there are more than one test sample on a casting, the samples shall be located as far away
from each other as possible.
B. Separate Cast Test Samples:
Two separately cast test samples shall be cast per heat/heat treatment batch with equivalent thickness to
the maximum 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 coupons:
Thin section:
≤
50 mm
- Mid thickness (T/2)
Thick section:
> 50 mm
- Sub surface and T/3
5.4.4 Test
methods
The tensile testing shall be carried out according to ISO 6892 or equivalent.
The Charpy V-notch testing shall be carried out according to ISO 148 or equivalent. The longitudinal axis of
the specimen shall 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
Steel grade Yield
strength
R
e
min*
MPa
Tensile
strength
R
m
min
MPa
Elongation
A
5
min
%
Reduction
of area
Z min
%
IMpact test
KV min
J aver./single
KV test
temp.
o
C
Ratio
R
e/
R
m
max
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 R
e
and R
m
may be agreed
* R
e
= R
eH
or R
p
0,2
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 of
additional tests, preferably from the same test coupon and position. All results from retest shall meet the
requirements.
If retesting fails, the casting will be rejected. However the manufacturer may choose to carry out a reheat
treatment 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
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 and
hot tears.
NORSOK standard M-122
Rev. 1, June 2003
NORSOK standard
Page 10 of 15
Other surface discontinuities shall meet the requirements specified for MT.
Surface roughness shall as a minimum be as follows, ref. Recommendation Technique No. 359-01 du
Bureau 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, ref. ISO 2632/III:
- N
10
(Ra
≤
12
µ
m) on surfaces subject UT with normal probes
- N
9
(Ra
≤
6
µ
m) on surfaces subject UT with angel probes
- N
10
(Ra
≤
12
µ
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, ASNT-TC-1A or Purchaser
approved equivalent. Personnel performing RT exposures 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 personnel shall 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 possessed
certificates and expiry dates. This list shall be made available to Purchaser on request.
6.4
Extent of testing
The extent of NDT shall be as per Table 3.
NORSOK standard M-122
Rev. 1, June 2003
NORSOK standard
Page 11 of 15
Table 3 - Extent of NDT
Methods
Areas and volume to be
examined
Extent of
NDT
%
Time for examination
1)
Visual
examinations
Surface from inside and outside. 100
F
Magnetic particle
testing
Surface from inside and outside.
Excavated grooves before start
of repair welding.
100
100
F
Radiographic
testing
Weld End Zones.
Area 3 x thickness of the edge,
or minimum 100 mm
100 2)
Questionable indications
detected by ultrasonic testing
100
Ultrasonic testing Normal probes. Volumetric
testing (from all accessible
inside & outside
100
Angle probes. Areas where the
angles between front and back
surfaces of the casting exceed
15
°
(non-parallel)
100
Angle probes. Areas where loss
of back wall echo occurs.
100
Angle probes. Indications from
the testing with normal probes.
100
Repaired areas where the
defects were detected by
radiography or ultrasonic testing.
100 F
Notes:
1)
F means that the NDT shall be carried out in the final repair welded and PWHT condition. Otherwise, the NDT may be carried out
before the final repair welding and PWHT.
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 acceptance criteria as specified in 9.5/Table 9.5
Inspection Category A+B.
6.5 Test
methods
6.5.1
Magnetic particle testing
Magnetic particle testing shall be carried out according to ASME Section V, Article 7 or equivalent. An NDT
procedure shall be prepared. The procedure shall show the acceptance criteria.
6.5.2 Radiographic
testing
Radiographic testing shall be carried out in accordance with ASME Section V, Article 3. A written procedures
shall be prepared as specified in T-321.2. The procedure shall include the additional information:
-
shooting sketches as specified in SE – 1030, Appendix XI, Radiographic Standard Shooting Sketch
(RSS)
-
location for IQI
- acceptance
criteria.
6.5.3 Ultrasonic
testing
Ultrasonic testing shall be carried out in accordance with ASME V, Article 5 using normal probes and angle
probes.
NORSOK standard M-122
Rev. 1, June 2003
NORSOK standard
Page 12 of 15
6.5.3.1 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 and
probes to be used
- acceptance
criteria
-
reporting and identification system
6.5.3.2 Probes
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 size
diameter 10-24 mm
2-4 Mhz, 45
°
-70
°
crystal size,
approx. 8x9 mm
> 100 mm
2mhz, crystal size
diameter 10-24 mm
2-4MHz, 45
°
-70
°
crystal size, approx.
20x22 mm
Notes:
-
Crystal size shall be selected to give optimum coverage and coupling to test surface.
-
Twin crystal probes shall be used for evaluation of indications close to the surface.
-
All available probes shall be used for assessment of indications.
6.5.3.3 Calibration blocks
The flat bottom holes in the reference blocks in ASTM A 609, fig 1 shall have a diameter equal to 3 mm for
sensitivity setting for normal probes.
One additional reference block is required having metal distance equal to 10 mm for assessment of
indications close to the surface.
6.5.3.4 Ultrasonic
attenuation
The ultrasonic attenuation in the casting shall be checked at different typical locations of the casting. The
difference 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 clause 6.6.2, 6.6.3 and 6.6.4 and secure that these
meet the design requirements for the cast steel materials. Purchaser shall be informed if more stringent
acceptance criteria have to be applied. Revised acceptance criteria shall be implemented on drawings, NDT
procedures and NDT reports.
The castings are devided in Zone 1, 2 and 3 as follows, unnless otherwise shown on drawings:
Zone 1:
0-30 mm from all finished surfaces and all critical zones independent of thickness
Zone 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.
6.6.2 Visual
examination
All surfaces shall show evidence of good workmanship. (Ref. is made to surface requirements, Paragraph
6.2 and acceptance criteria for MT, Paragraph 6.6.5).
6.6.3 Radiographic
testing
Acceptance criteria related to type of discontinuity and zones are given in Table 5
NORSOK standard M-122
Rev. 1, June 2003
NORSOK standard
Page 13 of 15
Table 5 – Acceptance criteria for radiographic testing
Zone
Type of discontinuity
Acceptance standard
Cracks Not
acceptable
Gas porosity
ASTM E186, E280, E446, level A2
Inclusions
ASTM E186, E280, E446, level B2
1
Shrinkage
ASTM E186, E280, E446, level C2
Cracks Not
acceptable
Gas porosity
ASTM E186, E280, E446, level A4
Inclusions
ASTM E186, E280, E446, level B4
2
Shrinkage
ASTM E186, E280, E446, level C4
Cracks Not
acceptable
Gas porosity
Inclusions
3
Shrinkage
Shall meet the requirements of NORSOK M 101:
Inspection category A + B Table 9.5
6.6.4 Ultrasonic
testing
Acceptance criteria for ultrasonic testing are given below.
Zone 1
ASTM A 609 Table 2 - Level 1 Linear indications are not acceptable.
Zone 2
ASTM A 609 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
9.5.
6.6.5
Magnetic particle testing
Acceptance criteria for magnetic particle testing are given in Table 6
Table 6 Acceptance criteria for magnetic 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
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 (at
the location of the defect) or maximum 15 mm, whichever is less. Arc-air gouged areas shall be ground. The
ground area shall be 100% magnetic particle tested to ensure complete elimination of the defective material.
All grinding shall be carried out in a way 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 repair
welds shall be recorded.
The maximum extent of repair welding shall not exceed 20% of the total surface area unless otherwise
agreed with the purchaser.
The excavations shall be suitably shaped to allow good access for welding. The groove shall be ground
smooth and be free from dirt, grease, oil, etc.
NORSOK standard M-122
Rev. 1, June 2003
NORSOK standard
Page 14 of 15
Welding consumable of low hydrogen content (max. 5 ml/HDM pr. 100 g, IIW-method) shall be used for
repair welding. The welding consumable shall be handled according to the consumable manufacturer's
recommendations.
Repair welding procedures shall be qualified according to NS-EN 288, ASME IX or equivalent with the
following additional requirements:
•
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 for the
parent metal.
•
Macrosection.
•
Hardness values shall not exceed 350 HV10.
Repair welders shall be qualified according to EN-NS 287, ASME IX or equivalent.
Castings repaired by welding shall be post weld heat treated at a temperature at least 15
°
C below the
tempering temperature. On completion of heat treatment the weld repairs and adjacent material shall be
ground smooth. All weld repairs shall be magnetic particle tested and major repairs shall additionally be
ultrasonic (or radiographic) tested. Weld repairs shall meet the quality level designated for that particular
area of the casting.
The foundry shall maintain records of repair welding, subsequent heat treatment and inspections traceable
to each casting repaired.
8 Dimensions/tolerances
Dimensions and required tolerances shall be as given on the relevant drawing of the casting or other
information supplied. If nothing is specified, ISO 8062 Grade CT 13 shall apply.
9 Surface
protection
Castings shall before delivery, be degreased, shot blasted to bright metal and protected by a shop primer
with a dry film thickness of approximately 20 µm.
All sharp edges shall be rounded and smoothed by
grinding 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).
10 Marking
Castings shall be marked for identification against a certificate. The marking shall include Contractor’s
identification and heat number.
All markings shall be carried out by die stamping or as cast in marks, and be framed by white painting. The
letters used for the stamping should be 15 mm in height.
NORSOK standard M-122
Rev. 1, June 2003
NORSOK standard
Page 15 of 15
11 Certificate
Certificate according to EN 10204 3.1b is required.
The certificate shall contain all relevant information including, but not restricted to the following:
•
purchaser’s 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.
