Petroleum, petrochemical and natural gas industries - Test methods for quality control of microstructure of austenitic/ferritic (duplex) stainless steel (ISO 17781:2017)

This document specifies quality control testing methods and test conditions for the characterization
of microstructure in relation to relevant properties in ferritic/austenitic (duplex) stainless steel
components supplied in the solution annealed condition and fabrication welds in the as welded
condition.
This document supplements the relevant product and fabrication standards with respect to destructive
testing methods including sampling of test specimens, test conditions and test acceptance criteria to
show freedom from deleterious intermetallic phases and precipitates in duplex stainless steels. In
addition, this document specifies the documentation of testing and test results by the testing laboratory.
NOTE 1 This document is based upon experience with duplex stainless steels in offshore oil and gas industry
applications including topside and subsea hydrocarbon service, sea water service, as well as structural use.
NOTE 2 The austenite spacing is relevant to the susceptibility of duplex stainless steels to hydrogen-induced
stress cracking (HISC) in subsea applications where cathodic protection is applied. This falls outside the scope of
this document. Reference is made to DNV/GL RP-F112[4].

Erdöl-, petrochemische und Erdgasindustrie - Werkstofftestanforderungen für nichtrostenden Duplexstahl (ISO 17781:2017)

Industries du pétrole, de la pétrochimie et du gaz naturel - Méthodes d'essai de contrôle de la qualité de la microstructure des aciers inoxydables (duplex) austénitiques/ferritiques (ISO 17781:2017)

ISO 17781:2017 spécifie les méthodes et les conditions d'essai de contrôle de la qualité pour caractériser la microstructure par rapport aux propriétés pertinentes des composants en acier inoxydable ferritique/austénitique (duplex) fournis à l'état recuit et les soudures de fabrication à l'état brut de soudage.
ISO 17781:2017 complète les normes de fabrication du produit concerné par rapport aux méthodes d'essais destructifs, y compris le prélèvement des éprouvettes, les conditions d'essai et les critères d'acceptation des essais, pour démontrer l'absence de phases intermétalliques préjudiciables et de précipités dans les aciers inoxydables duplex. De plus, le présent document précise la documentation des essais et des résultats des essais par le laboratoire d'essai.
NOTE 1 Le présent document se fonde sur l'expérience acquise avec des aciers inoxydables duplex dans des applications de plates-formes d'extraction en mer de pétrole et de gaz, y compris dans le cadre d'un fonctionnement en milieu hydrocarbure sous-marin ou en surface ou en service dans l'eau de mer ou pour une utilisation structurelle.
NOTE 2 L'espacement austénitique est pertinent pour la sensibilité des aciers inoxydables duplex à la fissuration par contrainte induite par l'hydrogène (HISC) dans les applications sous-marines en présence d'une protection cathodique. Cela ne relève pas du domaine d'application du présent document. Cela relève du domaine d'application du DNV/GL RP-F112[4].

Petrokemična industrija ter industrija za predelavo nafte in zemeljskega plina - Preskusne metode za kontrolo kakovosti mikrostrukture avstenitno-feritnega (dupleksnega) nerjavnega jekla (ISO 17781:2017)

Ta dokument določa preskusne metode za kontrolo kakovosti in preskusne pogoje za karakterizacijo mikrostrukture glede na ustrezne lastnosti komponent iz avstenitno-feritnega (dupleksnega) nerjavnega jekla, ki so dobavljene v žarjenem stanju, in proizvodnih zvarov v varjenem stanju.
Ta dokument dopolnjuje ustrezne standarde proizvodov in izdelave v zvezi s porušitvenimi preskusnimi metodami, vključno z vzorčenjem, preskusnimi pogoji in merili sprejemljivosti preskusa, za dokazovanje neprisotnosti zdravju škodljivih intermetalnih faz in izločkov v dupleksnih nerjavnih jeklih. Dokument poleg tega določa dokumentacijo za preskušanje in rezultate preskusa iz laboratorija za preskušanje.
OPOMBA 1: Ta dokument temelji na izkušnjah z dupleksnimi nerjavnimi jekli, ki se uporabljajo v industriji za predelavo nafte in zemeljskega plina, med drugim v sistemih za rokovanje z ogljikovodiki, sistemih za rokovanje z morsko vodo in uporabo v strukturah na palubi in pod morsko gladino.
OPOMBA 2: Avstenitni razmak je pomemben za določanje občutljivosti dupleksnega nerjavnega jekla na inducirano vodikovo napetostno pokanje (HISC) pri uporabi pod vodo, kjer se uporablja katodna zaščita. Slednje ne spada na področje uporabe tega dokumenta. Dokument se sklicuje na dokument DNV/GL RP-F112[4].

General Information

Status
Published
Public Enquiry End Date
11-Jul-2016
Publication Date
19-Sep-2017
Technical Committee
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
12-Sep-2017
Due Date
17-Nov-2017
Completion Date
20-Sep-2017

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SLOVENSKI STANDARD
SIST EN ISO 17781:2017
01-november-2017
3HWURNHPLþQDLQGXVWULMDWHULQGXVWULMD]DSUHGHODYRQDIWHLQ]HPHOMVNHJDSOLQD
3UHVNXVQHPHWRGH]DNRQWURORNDNRYRVWLPLNURVWUXNWXUHDYVWHQLWQRIHULWQHJD
GXSOHNVQHJD QHUMDYQHJDMHNOD ,62

Petroleum, petrochemical and natural gas industries - Test methods for quality control of

microstructure of austenitic/ferritic (duplex) stainless steel (ISO 17781:2017)
Erdöl-, petrochemische und Erdgasindustrie - Werkstofftestanforderungen für
nichtrostenden Duplexstahl (ISO 17781:2017)

Industries du pétrole, de la pétrochimie et du gaz naturel - Méthodes d'essai de contrôle

de la qualité de la microstructure des aciers inoxydables (duplex)
austénitiques/ferritiques (ISO 17781:2017)
Ta slovenski standard je istoveten z: EN ISO 17781:2017
ICS:
75.180.01 Oprema za industrijo nafte in Equipment for petroleum and
zemeljskega plina na splošno natural gas industries in
general
77.140.20 Visokokakovostna jekla Stainless steels
SIST EN ISO 17781:2017 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 17781:2017
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SIST EN ISO 17781:2017
EN ISO 17781
EUROPEAN STANDARD
NORME EUROPÉENNE
August 2017
EUROPÄISCHE NORM
ICS 75.180.01
English Version
Petroleum, petrochemical and natural gas industries - Test
methods for quality control of microstructure of
ferritic/austenitic (duplex) stainless steels (ISO
17781:2017)

Industries du pétrole, de la pétrochimie et du gaz Erdöl-, petrochemische und Erdgasindustrie -

naturel - Méthodes d'essai de contrôle de la qualité de Prüfverfahren für die Qualitätslenkung von

la microstructure des aciers inoxydables (duplex) Microstrukturen von austenitisch/ferritisch

austénitiques/ferritiques (ISO 17781:2017) nichtrostendem Duplexstahl (ISO 17781:2017)

This European Standard was approved by CEN on 1 July 2017.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this

European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references

concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN

member.

This European Standard exists in three official versions (English, French, German). A version in any other language made by

translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management

Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,

Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,

Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,

Turkey and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels

© 2017 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 17781:2017 E

worldwide for CEN national Members.
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SIST EN ISO 17781:2017
EN ISO 17781:2017 (E)
Contents Page

European foreword ....................................................................................................................................................... 3

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SIST EN ISO 17781:2017
EN ISO 17781:2017 (E)
European foreword

This document (EN ISO 17781:2017) has been prepared by Technical Committee ISO/TC 67 “Materials,

equipment and offshore structures for petroleum, petrochemical and natural gas industries” in

collaboration with Technical Committee CEN/TC 12 “Materials, equipment and offshore structures for

petroleum, petrochemical and natural gas industries” the secretariat of which is held by NEN.

This European Standard shall be given the status of a national standard, either by publication of an

identical text or by endorsement, at the latest by February 2018, and conflicting national standards

shall be withdrawn at the latest by February 2018.

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. CEN shall not be held responsible for identifying any or all such patent rights.

According to the CEN-CENELEC Internal Regulations, the national standards organizations of the

following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,

Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia,

France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta,

Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,

Turkey and the United Kingdom.
Endorsement notice

The text of ISO 17781:2017 has been approved by CEN as EN ISO 17781:2017 without any modification.

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SIST EN ISO 17781:2017
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SIST EN ISO 17781:2017
INTERNATIONAL ISO
STANDARD 17781
First edition
2017-07
Petroleum, petrochemical and
natural gas industries — Test
methods for quality control of
microstructure of ferritic/austenitic
(duplex) stainless steels
Industries du pétrole, de la pétrochimie et du gaz naturel — Méthodes
d’essai de contrôle de la qualité de la microstructure des aciers
inoxydables (duplex) austénitiques/ferritiques
Reference number
ISO 17781:2017(E)
ISO 2017
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SIST EN ISO 17781:2017
ISO 17781:2017(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2017, Published in Switzerland

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form

or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior

written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of

the requester.
ISO copyright office
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO 2017 – All rights reserved
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SIST EN ISO 17781:2017
ISO 17781:2017(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms, definitions and abbreviated terms ................................................................................................................................ 2

3.1 Terms and definitions ....................................................................................................................................................................... 2

3.2 Abbreviated terms ............................................................................................................................................................................... 3

4 Sampling of test specimens ....................................................................................................................................................................... 4

4.1 General ........................................................................................................................................................................................................... 4

4.2 Casting test blocks................................................................................................................................................................................ 6

4.3 Welds in the as welded condition ........................................................................................................................................... 6

5 Test methods ............................................................................................................................................................................................................. 7

5.1 General ........................................................................................................................................................................................................... 7

5.2 Microstructural examination ...................................................................................................................................................... 7

5.2.1 General...................................................................................................................................................................................... 7

5.2.2 Preparation of specimen ........................................................................................................................................... 7

5.2.3 Etching of specimens ........................................................................................................................................... ......... 7

5.2.4 Microstructural evaluation of test specimens ........................................................................................ 8

5.3 Ferrite content measurement .................................................................................................................................................10

5.3.1 Test standard and conditions .............................................................................................................................10

5.3.2 Acceptance criteria .....................................................................................................................................................11

5.3.3 Reporting .............................................................................................................................................................................11

5.4 Charpy V-notch impact toughness test ............................................................................................................................11

5.4.1 Test standard and conditions .............................................................................................................................11

5.4.2 Acceptance criteria .....................................................................................................................................................11

5.4.3 Reporting .............................................................................................................................................................................12

5.5 Corrosion test ........................................................................................................................................................................................12

5.5.1 Test standard and conditions .............................................................................................................................12

5.5.2 Preparation of test specimens ...........................................................................................................................13

5.5.3 Acceptance criteria .....................................................................................................................................................13

5.5.4 Reporting .............................................................................................................................................................................13

Annex A (informative) Chemical compositions of duplex stainless steels .................................................................14

Annex B (informative) Preparation and etching for microstructural examination .........................................16

Bibliography .............................................................................................................................................................................................................................18

© ISO 2017 – All rights reserved iii
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SIST EN ISO 17781:2017
ISO 17781:2017(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards

bodies (ISO member bodies). The work of preparing International Standards is normally carried out

through ISO technical committees. Each member body interested in a subject for which a technical

committee has been established has the right to be represented on that committee. International

organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.

ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of

electrotechnical standardization.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www .iso .org/ patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation on the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO’s adherence to the

World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following

URL: w w w . i s o .org/ iso/ foreword .html.

This document was prepared by Technical Committee ISO/TC 67, Materials, equipment and offshore

structures for petroleum, petrochemical and natural gas industries.
iv © ISO 2017 – All rights reserved
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SIST EN ISO 17781:2017
ISO 17781:2017(E)
Introduction

The aim of this document is to establish common test methods for quality control of microstructure of

ferritic/austenitic (duplex) stainless steels for the oil and gas industry, enabling the manufacturers to

apply the same test procedures for their clients.

Duplex stainless steels have a dual phase microstructure consisting of ferrite and austenite. Ideally,

these phases are present in equal proportions; although in alloys which are commercially available, the

ferrite phase volume fraction can vary between 35 % and 65 % for products in the solution annealed

condition. They are characterized by high-chromium (19 % to 33 %) and low-nickel contents compared

with austenitic stainless steels.

Duplex stainless steels are prone to precipitation of intermetallic phases, carbides and/or nitrides

possibly causing embrittlement and reduced corrosion resistance. The formation of intermetallic

phases such as Sigma, σ, and Chi, χ, occurs depending on exposure time in the approximate temperature

range 590 °C to 1 000 °C (1 094 °F to 1 832 °F) and decomposition of ferrite to Alpha Prime occurs in the

range 300 °C to 540 °C (572 °F to 1 004 °F).

The microstructure of components or fabrication welds is affected by amongst others the thermal-

mechanical history associated with hot working, solution annealing and with subsequent forming

and welding. The destructive test methods with acceptance criteria specified herein are considered

relevant to verify that exposure time at above stated temperature ranges have been within acceptable

limits and to ensure that desired corrosion resistance and mechanical properties are obtained in final

products.
© ISO 2017 – All rights reserved v
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SIST EN ISO 17781:2017
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SIST EN ISO 17781:2017
INTERNATIONAL STANDARD ISO 17781:2017(E)
Petroleum, petrochemical and natural gas industries —
Test methods for quality control of microstructure of
ferritic/austenitic (duplex) stainless steels
1 Scope

This document specifies quality control testing methods and test conditions for the characterization

of microstructure in relation to relevant properties in ferritic/austenitic (duplex) stainless steel

components supplied in the solution annealed condition and fabrication welds in the as welded

condition.

This document supplements the relevant product and fabrication standards with respect to destructive

testing methods including sampling of test specimens, test conditions and test acceptance criteria to

show freedom from deleterious intermetallic phases and precipitates in duplex stainless steels. In

addition, this document specifies the documentation of testing and test results by the testing laboratory.

NOTE 1 This document is based upon experience with duplex stainless steels in offshore oil and gas industry

applications including topside and subsea hydrocarbon service, sea water service, as well as structural use.

NOTE 2 The austenite spacing is relevant to the susceptibility of duplex stainless steels to hydrogen-induced

stress cracking (HISC) in subsea applications where cathodic protection is applied. This falls outside the scope of

[4]
this document. Reference is made to DNV/GL RP-F112 .
2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements of this document. For dated references, only the edition cited applies. For

undated references, the latest edition of the referenced document (including any amendments) applies.

ISO 148-1, Metallic materials — Charpy pendulum impact test — Part 1: Test method

ISO 15614-1 , Specification and qualification of welding procedures for metallic materials — Welding

procedure test — Part 1: Arc and gas welding of steels and arc welding of nickel and nickel alloys)

ASTM A 370, Standard test methods and definitions for mechanical testing of steel products

ASTM A 1058, Standard test methods and definitions for mechanical testing of steel products — Metric

ASTM A 1084, Standard test method for detecting detrimental phases in lean duplex austenitic/ferritic

stainless steels
ASTM E 3, Standard practice for preparation of metallographic specimens

ASTM E 562, Standard test method for determining volume fraction by systematic manual point count

ASTM E 1245, Standard practice for determining the inclusion or second-phase constituent content of

metals by automatic image analysis

ASTM G 48, Standard test methods for pitting and crevice corrosion resistance of stainless steels and

related alloys by use of ferric chloride solution

1) For the purpose of this document, the following documents are considered equivalent: ASME Boiler and

[2]
pressure vessel code, section IX Welding and brazing qualifications .
© ISO 2017 – All rights reserved 1
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SIST EN ISO 17781:2017
ISO 17781:2017(E)
3 Terms, definitions and abbreviated terms
For the purposes of this document, the following terms and definitions apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— IEC Electropedia: available at http:// www .electropedia .org/
— ISO Online browsing platform: available at http:// www .iso .org/ obp

NOTE For limitations in chemical composition of each specific material grade of duplex stainless steel,

reference is made to the appropriate product standards or UNS number. For nominal chemical composition of

duplex stainless steels and grouping of different types, used within this document, reference is made to Annex A.

3.1 Terms and definitions
3.1.1
centreline intermetallic stringer

group of intermetallic phases (3.1.4) aligned within the mid-thickness area due to alloy segregation

Note 1 to entry: They can be observed as both continuous and discontinuous precipitates.

3.1.2
fabrication

building of structures or equipment by cutting, bending, and assembling processes such as welding,

riveting, threaded fasteners or other joining methods
3.1.3
ferritic/austenitic (duplex) steel

stainless steel (3.1.8) with a high-chromium mass fraction (19 % to 33 %) with or without molybdenum

additions up to 5 %, and a nickel mass fraction intermediate to those of ferritic and austenitic

stainless steels
3.1.4
intermetallic phase

solid-state compounds, containing two or more metallic elements, whose ordered structure differs

from that of its constituents

Note 1 to entry: In duplex stainless steel, the most relevant phases are identified as σ-phase, χ-phase and R-phase.

3.1.5
lot

finite quantity of products from the same heat (or melt), same manufacturing process steps and same

heat treatment load

Note 1 to entry: For continuous and semi-continuous furnaces, the lot definition should comply with the

applicable product standards.
3.1.6
non-metallic precipitate

solid-state compounds, containing two or more elements, whose ordered structure differs from that of

its constituents

Note 1 to entry: In duplex stainless steel, the relevant non-metallic precipitates are chromium carbides and

nitrides.
2 © ISO 2017 – All rights reserved
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SIST EN ISO 17781:2017
ISO 17781:2017(E)
3.1.7
pitting resistance equivalent number
PREN

number indicating the resistance of stainless steel (3.1.8) to pitting corrosion related to chemical

composition and derived from one of the equations PREN = % Cr + 3,3 % Mo + 16 % N or PREN = % Cr +

3,3 × % (Mo + 0,5W) + 16 × % N (mass fraction)

Note 1 to entry: All PREN limits are absolute limits based upon the heat analysis. The calculated value is not to be

rounded.
3.1.8
stainless steel

steel with at least 10,5 % mass fraction or more chromium, possibly with other elements added to

secure special properties
3.1.9
type 20Cr duplex Group A
ferritic/austenitic stainless steel (3.1.8) alloys with 24,0 ≤ PREN < 28,0
3.1.10
type 20Cr duplex Group B
ferritic/austenitic stainless steel (3.1.8) alloys with 28,0 ≤ PREN < 30,0
3.1.11
type 22Cr duplex

ferritic/austenitic stainless steel (3.1.8) alloys with 30,0 ≤ PREN < 40,0 and Cr ≥ 19 % (mass fraction)

3.1.12
type 25Cr duplex
ferritic/austenitic stainless steel (3.1.8) alloys with 40,0 ≤ PREN < 48,0
3.1.13
type 27Cr duplex

ferritic/austenitic stainless steel (3.1.8) alloys with 48,0 ≤ PREN ≤ 55,0 and Cr ≤ 33,0 % (mass fraction)

3.2 Abbreviated terms
For the purposes of this document, the following abbreviated terms are used.
ASTM American society for testing and materials
CVN Charpy V-notch
HIP hot isostatically-pressed
NA not applicable
OD outside diameter
PREN pitting resistance equivalent number
QL quality level
T ruling section thickness
UNS unified numbering system
© ISO 2017 – All rights reserved 3
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SIST EN ISO 17781:2017
ISO 17781:2017(E)
4 Sampling of test specimens
4.1 General

The test samples shall be made from a sacrificial product or from a prolongation/extension of a

product in the final solution annealed condition with location of test specimens as defined in Table 1

representing the thickest product within the lot. Alternatively, a representative test block may be used

when agreed with the purchaser.
4 © ISO 2017 – All rights reserved
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SIST EN ISO 17781:2017
ISO 17781:2017(E)
Table 1 — Sampling of test specimens dependent of product
Product
Product Test sample Test method Test direction Thickness location
dimension
Plates, and Prolongation of All CVN Transverse Mid-thickness
seamless tubes, the product
Corrosion, Transverse Full thickness
pipes and fit-
Microstructure
tings
Welded pipes Prolongation or All CVN Transverse Mid-thickness
and fittings welded exten-
c b
Corrosion , Transverse Full thickness
sion piece
Microstructure
Bars and long Prolongation OD or section CVN Longitudinal Mid-thickness
solid forgings thickness
Corrosion, Transverse Surface to centre
without weld <50 mm (2 in)
Microstructure
end
OD or section CVN Longitudinal 1/4 thickness
thickness
Corrosion, Transverse Surface to centre
≥50 mm (2 in)
Microstructure
Flanges and Sacrificial prod- All CVN Both longitudinal Mid-thickness
other hollow uct or prolonga- and tangential to weld end
contour shaped tion at weld end centre bore
forgings with
Corrosion, Longitudinal or Full thickness
weld end includ-
Microstructure tangential weld end
ing tees
HIP products Sacrificial prod- All CVN Any direction Mid-thickness
with weld end uct or prolonga- weld end
tion at weld end
Corrosion, Any direction Full thickness
with greatest
Microstructure weld end
wall thickness
HIP products Sacrificial prod- Section thick- CVN Any direction Mid-thickness
without weld uct or prolon- ness <50 mm
Corrosion, Any direction Surface to centre
end gation at cross (2 in)
Microstructure
section with
Section thick- CVN Any direction 1/4 thickness
greatest wall
ness ≥50 mm
thickness
Corrosion, Any direction Surface to centre
(2 in)
Microstructure
Castings Sacrificial Test block CVN Any direction Mid-thickness
product or test thickness Corrosion,
block (see 4.2) <50 mm (2 in) Microstructure
Test block CVN Any direction Within hatched
thickness Corrosion, area (see Figure 1)
≥50 mm (2 in) Microstructure
For definition of test directions, reference is made to ASTM A 370/ASTM A 1058.

For products with large sections, the corrosion test specimen shall be taken transverse to the longitudinal axis with

dimensions of approximately 6 mm × 25 mm (1⁄4 in × 1 in) by thickness. For very large sections, the thickness dimension of

the specimen can be cut so that one-half to two-thirds of the product thickness is tested.

For welded products, the test specimens for corrosion testing and microstructure examination shall include weld

metal and the heat affected zone of parent metal. For products with wall thickness exceeding 25 mm, more than one (1)

specimen can be taken to cover full thickness. In such a case, all specimens shall fulfil the specified criteria.

When flange body thickness <50 mm (2 in) or weld end OD ≤100 mm (4 in), test specimens may be taken from the

flange body mid-thickness in tangential direction.

For all products, the mid-length of the test specimens shall be located one T or minimum 50 mm to any

second surface provided this is feasible within the size of the test sample/sacrificial product.

CVN testing is required when the wall thickness is ≥6 mm, wherever geometry permits.

For all products, the notch axis of CVN test specimens shall be positioned perpendicular to the closest

outer surface.
© ISO 2017 – All rights reserved 5
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SIST EN ISO 17781:2017
ISO 17781:2017(E)

For welded products, two (2) sets of three (3) CVN impact toughness test specimens shall be taken from

mid-thickness of the component, one (1) with notch located in base material and the other notched in

the weld metal.

For forgings, HIP products and fittings, dimensioned sketches shall be established showing type, size

and orientation of test specimens to be taken from a prolongation of product or a sacrificial product.

4.2 Casting test blocks

Test blocks shall be integral or gated with the casting(s) they represent and shall accompany the

castings through all heat treatment operations. During any heat treatment of products, which the test

block represents, the test blocks shall be tack welded onto the casting and shall accompany the castings

through all heat treatment operations. Alternatively, a sacrificial product may be used as a test sample.

The thickness of the test block shall be equal to the thickest section of the casting(s) represented. For

flanged components, the largest flange thickness should be used as the ruling section.

Dimensions of test blocks and location of test specimens within the test blocks are shown in Figure 1 for

integral and gated test blocks, respectively. All test specimens shall be taken within the cross hatched

area. When the thickness T of the test block is ≤50 mm, the longitudinal axis of test specimens shall be

located in the centre of the test block.
Figure 1 — Int
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