1、BS 8701:2016 Full ring ovalization test for determining the susceptibility to cracking of linepipe steels in sour service Test method BSI Standards Publication WB11885_BSI_StandardCovs_2013_AW.indd 1 15/05/2013 15:06Publishing and copyright information The BSI copyright notice displayed in this docu
2、ment indicates when the document was last issued. The British Standards Institution 2016 Published by BSI Standards Limited 2016 ISBN 978 0 580 89474 9 ICS 77.060 The following BSI references relate to the work on this document: Committee reference PSE/17 Draft for comment 16/30319903 DC Publication
3、 history First published June 2016 Amendments issued since publication Date Text affected BS 8701:2016 BRITISH STANDARDContents Foreword iii Introduction 1 1 Scope 1 2 Normative references 2 3 Terms and definitions 2 4 Principle 5 5 Reagents 5 6 Apparatus 6 7 Samples 6 8 Surface preparation 7 9 Proc
4、edure for test specimens with internal loading 7 10 Expression of results 12 Annexes Annex A (normative) Ultrasonic examination of pipe, plate and welds during accelerated laboratory tests 13 Annex B (normative) Ring loading 17 Annex C (informative) Typical internal and external load application rig
5、s for use in the full ring test 27 Annex D (normative) Chemistry of test solutions 28 Annex E (informative) Analysis of test solution iodimetric titration procedure 29 Annex F (informative) Illustrated summary of the full ring test procedure 30 Annex G (informative) Hydrogen sulfide (H 2 S) health a
6、nd safety considerations 38 Annex H (informative) Sample identification and test record, Form 1 39 Annex I (informative) Sample identification and test record, Form 2 40 Annex J (informative) Acceptance criteria 43 Annex K (informative) Sulfide stress corrosion (SSC) and hydrogen induced cracking (H
7、IC) 43 Annex L (informative) Explanatory notes on test method: Galvanic Coupling 45 Annex M (informative) Modified test procedure for externally loaded test specimens (Diameter 12 in. 305 mm) 45 Annex N (informative) Magnetic particular inspection (MPI) procedure 46 Bibliography 47 List of figures F
8、igure 1 Full ring test using internal loading techniques 8 Figure 2 Modified full ring test using external loading technique 8 Figure A.1 Most common crack locations 13 Figure B.1 Gauge positions for seamless ring specimens 20 Figure B.2 Gauge positions for ring specimens that contain only a longitu
9、dinal seam weld 21 Figure B.3 Gauge positions on specimens having a spirally wound seam only 22 Figure B.4 Gauge positions for ring specimens that contain only a girth weld seam 22 Figure B.5 Gauge positions for ring specimens that contain both circumferential and longitudinal weld seams and have an
10、 angular gap of between 5 and 175 between longitudinal seams 23 Figure B.6 Modified gauge positions for ring specimens that contain both circumferential and longitudinal weld seams and have an angular off-set of 5 or 175 to 185 between longitudinal weld seams 24 Figure B.7 Gauge positions on specime
11、ns having spirally wound weld seams combined with a girth weld 24 BRITISH STANDARD BS 8701:2016 The British Standards Institution 2016 iFigure B.8 Gauge positions for ring specimens that contain both circumferential and longitudinal weld seams where individual plates are of unequal thickness 25 Figu
12、re C.1 External loading blocks used for ring specimens below 12 in. (305 mm) in diameter 27 Figure C.2 Internal loading rig used for ring specimens above 12 in. (305 mm) in diameter 28 Figure F.1 Ring machined and grit blasted 31 Figure F.2 Ring strain gauged 32 Figure F.3 Application of internal an
13、d external loads 32 Figure F.4 Conversion of ring into test cell 33 Figure F.5 On-line ultrasonic inspection 34 Figure F.6 Full ring after test 34 Figure F.7 Example of ultrasonic indications after test 35 Figure F.8 Example of recorded permeation data 35 Figure F.9 Typical HIC crack 36 Figure F.10
14、Typical weld SSC 37 Figure F.11 Typical soft zone crack 37 Figure F.12 Typical SOHIC 38 Figure H.1 Sample identification and test record, Form 1 39 Figure I.1 Full ring test loading data sheets, Form 2 40 Figure L.1 Typical example of potential change on a girth welded sample 45 List of tables Table
15、 B.1 Load level ranges 26 Table D.1 Standard NACE TM0177 solution A composition 29 Table D.2 Highly buffered solution composition 29 Table F.1 List of full ring test procedure figures 31 Table G.1 Chemical and physical properties of hydrogen sulfide 38 Summary of pages This document comprises a fron
16、t cover, an inside front cover, pages i to iv, pages 1 to 48, an inside back cover and a back cover. BRITISH STANDARD BS 8701:2016 ii The British Standards Institution 2016Foreword Publishing information This British Standard is published by BSI Standards Limited, under licence from The British Stan
17、dards Institution, and came into effect on 30 June 2016. It was prepared by Technical Committee PSE/17, Materials and equipment for petroleum, petrochemical and natural gas industries. A list of organizations represented on this committee can be obtained on request to its secretary. Use of this docu
18、ment It has been assumed in the preparation of this British Standard that the execution of its provisions will be entrusted to appropriately qualified and experienced people, for whose use it has been produced. Presentational conventions The provisions of this standard are presented in roman (i.e. u
19、pright) type. Its methods are expressed as a set of instructions, a description, or in sentences in which the principal auxiliary verb is “shall”. Commentary, explanation and general informative material is presented in smaller italic type, and does not constitute a normative element. Where words ha
20、ve alternative spellings, the preferred spelling of the Shorter Oxford English Dictionary is used (e.g. “organization” rather than “organisation”). Contractual and legal considerations This publication does not purport to include all the necessary provisions of a contract. Users are responsible for
21、its correct application. Compliance with a British Standard cannot confer immunity from legal obligations. BRITISH STANDARD BS 8701:2016 The British Standards Institution 2016 iiiBRITISH STANDARD BS 8701:2016 This page deliberately left blank iv The British Standards Institution 2016Introduction Sou
22、r service cracking problems in susceptible pipeline steels are caused by the various forms of hydrogen damage due to the presence of wet hydrogen sulfide (H 2 S). The main mechanisms are hydrogen pressure induced cracking (HPIC) also called hydrogen induced cracking (HIC) or stepwise cracking (SWC),
23、 sulfide stress corrosion (SSC) and stress oriented hydrogen induced cracking (SOHIC). An industry proven technique for assessing pipeline steels is to stress a full ring specimen in a sour environment. The advantage of the full ring test specified in this British Standard is that it is not necessar
24、y to pressurize the linepipe full ring specimen to achieve the required stress loading and residual stresses are retained. Equivalent stresses can be produced using mechanical means to deform the pipe by ovalization. Additional advantages are representative sample and single sided exposure. This tes
25、t uses well tried experimental procedures to exert a known stress level at two regions on a full ring section of pipe steel. The pipe specimen is then exposed internally to the sour test solution, although some cases require the sour media externally. Ultrasonic monitoring and hydrogen permeation me
26、asurements are conducted regularly during the exposure period. Both crack initiation and propagation can therefore be monitored. Finally, a metallographic study of indications is undertaken to classify any defects found by the ultrasonic survey. The method has been in use since 1984, but in 1991 a J
27、oint Industry Sponsored Project was set up with the aim of systematically developing, defining and validating the full ring test. The resultant test method designed to determine the susceptibility of pipeline steels, bends, flanges and fittings, including all associated welds to hydrogen damage caus
28、ed by exposure to sour environments, was published by the UK HSE as OTI 95 635 1 and forms the basis of this British Standard. 1 Scope This British Standard gives a method for determining the susceptibility to cracking of steel pipes in sour service. This British Standard utilizes a tubular specimen
29、 comprising a full circumferential ring. The test method applies to any pipe with or without seam (longitudinal or spiral) or girth weld (with or without filler). NOTE 1 The specimen is usually a pipe but can also consist of flange neck or section of a bend, or other tubular component or a combinati
30、on of the above. This British Standard provides guidance on determination of specimen size to ensure it retains residual stresses from manufacture and welding. NOTE 2 See Clause 7 for specimen sizes. The method utilizes ovalization to simulate hoop stress, using mechanical loading on a tubular form.
31、 The specimen is subjected to single sided exposure to the sour test environment. NOTE 3 The test also allows measurement of hydrogen permeation rates which can provide useful information, such as highlighting the effects of galvanic coupling between materials of apparent compatibility. BRITISH STAN
32、DARD BS 8701:2016 The British Standards Institution 2016 12 Normative references The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the late
33、st edition of the referenced document (including any amendments) applies. BS EN 12668 (all parts), Non-destructive testing Characterization and verification of ultrasonic examination equipment BS EN ISO 2400, Non-destructive testing Ultrasonic testing Specification for calibration block No.1 BS EN I
34、SO 7963, Non-destructive testing Ultrasonic testing Specification for calibration block No.2 BS EN ISO 8044, Corrosion of metals and alloys Basic terms and definitions BS EN ISO 9712, Non-destructive testing Qualification and certification of NDT personnel BS EN ISO 11666, Non-destructive testing of
35、 welds Ultrasonic testing Acceptance levels BS EN ISO 16810, Non-destructive testing Ultrasonic testing General principles BS EN ISO 17640, Non-destructive testing of welds Ultrasonic testing Techniques, testing levels, and assessment ASTM D1193, Standard Specification for Reagent Water Other public
36、ations N1NACE TM0177, Laboratory Testing of Metals for Resistance to Sulfide Stress Cracking in H 2 S Environments. NACE International, PO Box 218340, Houston, TX. 77218. 3 Terms and definitions For the purposes of this British Standard, the terms and definitions given in BS EN ISO 8044 and the foll
37、owing apply. 3.1 ancillary components parts of the apparatus necessary for the test which are not the loading components to impart stress 3.2 anodic reaction involving an oxidation process and conjoint generation of electrons 3.3 cathodic reaction involving a reduction process with conjoint consumpt
38、ion of electrons 3.4 free corrosion potential naturally occurring electrode potential measured against a standard reference adopted by a metal undergoing corrosion in an aqueous environment 3.5 galvanic coupling electrical contact between two or more materials which exhibit different free corrosion
39、potentials within the same electrolyte, resulting in a combined mixed potential and an increased oxidation rate on the anodic material driven by the more noble material, determined by the relative areas and governed by efficiency of the cathodic reduction BRITISH STANDARD BS 8701:2016 2 The British
40、Standards Institution 20163.6 girth weld butt weld joining one pipe to another (or bend or flange) 3.7 hardness resistance of metal to plastic deformation, usually determined by indentation 3.8 heat affected zone (HAZ) portion of base metal not melted during brazing, cutting or welding, but whose mi
41、crostructure and properties are altered by the thermal cycle of these processes 3.9 hydrogen embrittlement action of absorbed atomic hydrogen to cause loss of ductility in a metal NOTE Hydrogen atoms are attracted to grain boundaries and slip plane movement is reduced. 3.10 hydrogen flux rate of hyd
42、rogen flow per unit area through a material 3.11 hydrogen pressure induced cracking (HPIC) cracking caused by atoms of hydrogen concentrating at discontinuities and forming molecular hydrogen within the steel NOTE 1 The resultant gas pressure induces cracking. NOTE 2 This is also called hydrogen ind
43、uced cracking (HIC), stepwise cracking and blister cracking (HIBC). 3.12 hydrogen permeation process of atomic hydrogen diffusion through a metal 3.13 longitudinal weld straight weld running along the longitudinal axis of a pipe 3.14 low alloy steel steel with a total alloying element content of les
44、s than approximately 5% but more than specified for carbon steel 3.15 measured strain E 1 , E 2 , E 3 surface strain as measured by various techniques in one or more of three known directions at the surface 3.16 microstructure crystalline structure of a metal as revealed by the microscopic examinati
45、on of a suitably prepared specimen 3.17 stress applied force per unit area existing on any object as a result of external mechanical or thermal influences acting in that direction 3.18 partial pressure total pressure multiplied by its mole fraction equal to each component in a gas mixture NOTE For a
46、n ideal gas, the mole fraction is equal to the volume fraction of the component. 3.19 plastic deformation permanent deformation caused by straining beyond the elastic limit BRITISH STANDARD BS 8701:2016 The British Standards Institution 2016 33.20 Poisson effect component subjected to loading in one
47、 direction causing extension or compression in that direction, experiencing tangentially a lesser opposing compression or expansion 3.21 Poissons ratio v dimensionless material constant (approximately constant for steel) given by the ratio of contraction/expansion per unit length tangential to the d
48、irection of loading over the expansion/contraction per unit length in the direction of loading 3.22 principal strain E x,y maximum and minimum strain levels existing at a point on the test surface acting at 90 to each other as calculated from measured strain values 3.23 residual stress res stress pr
49、esent in a component free of external forces or thermal gradients 3.24 stress oriented hydrogen induced cracking (SOHIC) staggered small cracks formed approximately perpendicular to the principal stress (residual or applied) resulting in a “ladder-like” crack array linking (sometimes small) pre-existing HIC cracks 3.25 sour environment environment where hydrogen sulfide exists in the presence of water NOTE For steel products a threshold concentration is
