1、BRITISH STANDARD BS7339:1990 Code of practice for Supplementary checking of metallic materials of construction in pressurized systemsBS7339:1990 This British Standard, having been prepared under the directionof the Pressure VesselsStandards Policy Committee, was published underthe authority of the B
2、oardofBSI and comes intoeffecton 31August1990 BSI08-1999 The following BSI references relate to the work on this standard: Committee reference PVE/- Draft for comment89/72561DC ISBN 0 580 18749 7 Committees responsible for this British Standard The preparation of this British Standard was entrusted
3、by the Pressure Vessels Standards Policy Committee (PVE/-) to sub committee PVE/-/7, upon which the following bodies were represented: Associated Offices Technical Committee British Chemical Engineering Contractors Association British Gas plc Electricity Supply Industry in England and Wales Engineer
4、ing Equipment and Materials Users Association Health and Safety Executive Independent Engineering Insurers Committee Institute of Quality Assurance Institution of Gas Engineers Institution of Plant Engineers Liquefied Petroleum Gas Industry Technical Association (UK) Lloyds Register of Shipping Powe
5、r Generation Contractors Association (BEAMA Ltd.) Process Plant Association Welding Institute Amendments issued since publication Amd. No. Date CommentsBS7339:1990 BSI 08-1999 i Contents Page Committees responsible Inside front cover Foreword ii 1 Scope 1 2 Definitions 1 3 Application and classifica
6、tion of pressurized systems subject to pmi 1 4 Regulation of pressurized systems subject to pmi 1 5 Pressurized systems not subject to pmi 1 6 Material checks 2 7 Records 2 Appendix A Common techniques used for checking materials 3 Appendix B Chemical analysis 3 Appendix C In situ spectrographic ana
7、lysis 3 Appendix D Eddy current 4 Appendix E Thermo-electric 4 Appendix F X-ray fluorescence 4 Appendix G Carbon determination by combustion technique 5 Appendix H Magnetic 5 Publication(s) referred to Inside back coverBS7339:1990 ii BSI 08-1999 Foreword This British Standard has been prepared under
8、 the direction of the Pressure Vessels Standards Policy Committee. The purpose of this British Standard is to supplement traditional methods of material identification which incorporate hard stamping and review of material certificates. It outlines further measures to be taken to minimize the likeli
9、hood of failure in service of any pressurized system, due to the use of incorrect material, where the consequences of such a failure would be unacceptable. It is not intended to ensure the complete conformity of materials to any given specification; where such guarantees are considered necessary, mo
10、re rigorous measures may be needed. Many pressurized systems require a range of ferritic steels, austenitic steels and non-ferrous materials in addition to plain carbon steel to withstand safely the operating conditions. Such materials may be required for enhanced strength, increased strength at hig
11、h temperatures, enhanced ductility at low temperatures, resistance to attack by hot hydrogen, resistance to corrosion, etc. It is not possible by visual means alone to distinguish between different metallic materials. Potential exists for material of different specifications to become mixed up unles
12、s a rigorous system of segregation, marking and control exists. Major failures have occurred in pressurized systems when the wrong material has been accidentally fabricated or introduced. Such errors invariably survive the final hydrostatic acceptance test (which is not intended to identify rogue ma
13、terials) only to reveal themselves in service when the material has been weakened by the operating conditions to the point of failure. Since special materials are usually needed for the more aggressive, hostile or demanding process conditions, the consequences of the use of the wrong material are at
14、 their greatest in such systems. There are also cases in which alloy material is built into carbon steel systems, again in error. In these circumstances the consequences can still be potentially damaging. Experience shows that by far the greatest number of errors occur in piping systems, in particul
15、ar the systems which are fabricated and assembled on construction sites from bulk issue materials. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard d
16、oes not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, pages1 to6, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This
17、 will be indicated in the amendment table on the inside front cover.BS7339:1990 BSI 08-1999 1 1 Scope This British Standard provides guidance on the supplementary checking of metallic materials used in operational plant and in the manufacture of pressurized systems including components such as pipin
18、g, pressure vessels, valves, pumps, fired heaters, boilers and associated weld deposits, etc. It is valid for checking either on site or at earlier stages, e.g.at the pressure component manufacturers, stockists or fabricators. These additional checks are intended to increase the level of confidence
19、established by traditional methods of material identification and recording. This British Standard is not intended to be applied in the material manufacturers works. NOTEThe titles of the publications referred to in this standard are listed on the inside back cover. 2 Definitions For the purposes of
20、 this British Standard the following definitions apply. 2.1 design authority the person authorized by the purchaser to be responsible for the design of the plant and equipment 2.2 operations authority the person responsible for the operation of the plant 2.3 inspecting authority the person authorize
21、d by the purchaser for the inspection of plant and equipment forming part of any pressurized system and for the inspection of any repairs or modifications to that plant and equipment. The inspecting authority may be the purchasers personnel, a contractor or one of the engineering inspecting organiza
22、tions 2.4 positive material identification (pmi) the designation used in industry to identify the supplementary checking of metallic materials of construction in pressurized systems 3 Application and classification of pressurized systems subject to pmi 3.1 Application 3.1.1 A pressurized system shou
23、ld be subject to supplementary material checking when the conditions under which it operates are such that a failure attributable to the inclusion of incorrect materials could occur and when the consequences of such failure are unacceptable with regard to the likely hazards to personnel or plant and
24、 in the following circumstances: a) where there is doubt about the identity of the material; or b) where there is a multiplicity of materials. NOTEThe service conditions to be assessed include pressure, temperature, susceptibility to corrosion, nature of fluid (toxic and/or flammable) and the locati
25、on of the component in relation to plant, buildings or personnel. Depending upon the location, or changes in other conditions, parts of a pressurized system may have differing degrees of risk associated with a possible loss of containment. Following this assessment, a decision can be made as to whet
26、her pmi is necessary. 3.1.2 Selection of the appropriate technique for checking from Appendix A should be carried out by a suitably qualified person taking into consideration such things as the following: a) range of material types and dimensions; b) need for qualitative or quantitative analysis; c)
27、 accessibility; d) ability of the method to differentiate between the relevant elements or properties. 3.2 Classification 3.2.1 For new projects, each pressurized system should be considered by the design authority and classified as pmi, in whole or in part, as appropriate. 3.2.2 For modification to
28、 existing plants, when replacement components are required or system modifications are to be carried out and the original drawings do not indicate the classification of the pressurized system, then the operations authority should, in conjunction with the design authority, identify and assess the sys
29、tem components as recommended in clause3. 4 Regulation of pressurized systems subject to pmi When pressurized systems in whole or in part are given the classification pmi this should be stated on the specification and record documents. 5 Pressurized systems not subject to pmi Where a system is not c
30、lassified as pmi, no special action should be taken.BS7339:1990 2 BSI 08-1999 NOTEThis should not be taken as meaning that it is of no concern whether or not the correct material is used for the system. All the usual procedures for correct specification, identification and scrutiny of test certifica
31、tes required by the contract should apply. 6 Material checks 6.1 General NOTEThe supply chain from raw material to installed component involves a number of processes and organizations, e.g.material and component manufacture, material stockist, site receipt and storage, where errors leading to incorr
32、ect usage can arise. It is in the longer term interest of all parties that procedures and controls at all stages of the chain should be adequate to prevent mistakes. Techniques such as those in BS5750 should be used. NOTEThe likelihood of accidental use of the wrong material increases with the numbe
33、r of separate material specifications. Error potential should be reduced by restricting the number of different specifications and by segregating specifications for off or on site fabrication in different workshops, by different contractors, etc., as well as by rigorous control of materials as state
34、d in this standard. It is very difficult to identify positively some special grades of material, e.g.impact tested carbon steel or low carbon grades of austenitic steel, by means of the non-destructive testing techniques outlined in Appendix B to Appendix H. Appropriate expert advice should be sough
35、t on the best technique to use and the accuracy which may be expected from it. NOTEIn some cases reliance may have to be placed on specially detailed documentation and marking of materials adequately tested at an earlier stage. Responsibilities for carrying out pmi should be agreed between the contr
36、acting parties. 6.2 Duties of component manufacturers and stockists It is the duty of the component manufacturers or stockists to ensure that materials are correctly marked. They should ensure that adequate measures are taken to satisfy themselves, and the purchaser, beyond reasonable doubt that the
37、 materials which they supply are those which were ordered and that they are correctly marked. Colour coding, character printing and hard stamping are aids to identification. In the case where pmi is specified, checking should be carried out using an approved instrument or technique described in Appe
38、ndix B to Appendix H or in such other ways as may be agreed. Chemical elements to be verified should be mutually agreed in advance. Material subjected to confirmatory checks should, if found to conform to its specification, be appropriately identified. The component manufacturer or stockist should s
39、upply a certificate which is traceable against material supplied with each consignment detailing the following: a) the specification to which the goods purport to conform; b) the check tests applied; c) the marking indicating that appropriate check tests have been applied and the material has been f
40、ound to conform to its specification. Such certification should be additional to any requirements of the material specification relating to the raw materials in question. 6.3 Fabricator All parts of pressurized systems classified as pmi should be checked either during or after fabrication/erection t
41、o ensure that all materials conform to those specified. Each component which is built into the system should be checked, including weld metal. For some services, flange bolting and gaskets should also be checked. NOTEAt the present time, the materials checking techniques available can only check the
42、 surface composition of welds which may not be representative of lower layers. The checks referred to above apply to both shop and site fabricated erected items at the time they are fabricated/erected to occupy their final place in the pressurized system. The checks may be relaxed for clearly marked
43、, identified and documented items which have been prefabricated under similar close control off site. Such relaxation should be agreed by the design authority. In no case where pmi is specified should final checking be totally eliminated; a recommended10% minimum of all items should be checked after
44、 fabrication/erection even when it is believed that rigorous off site control has been applied. In the event of failure within the10% off site control band, action agreed in advance should be taken. 7 Records Records of all materials checked in accordance with this standard, both on and off site, an
45、d the results and methods used should be retained in the plant records.BS7339:1990 BSI 08-1999 3 Appendix A Common techniques used for checking materials The technique adopted for pmi will depend on many factors such as the variety of materials which have to be scanned and their key elements for pos
46、itive checking, the analytical capability of the technique or instrument used and environmental factors such as temperature, access, area classification, the importance of absolute accuracy, etc. Some of the techniques available and their advantages and disadvantages are outlined in Appendix B to Ap
47、pendix H. Other techniques, such as visual examination, on site metallography, spark testing or hardness testing, may be applicable in certain specific circumstances. New and improved instruments are continually being introduced and may affect the balance of advantages and disadvantages in Appendix
48、B to Appendix H. This, coupled with the implications of the specific requirements in each particular case, makes it advisable to consult specialists on the appropriate technique to use. Personnel used for carrying out these checks should have suitable training and experience to the satisfaction of t
49、he operations authority. Appendix B Chemical analysis B.1 Physical removal of a piece of metal for laboratory analysis NOTEIn cases of dispute chemical analysis should be in accordance with BS6200. B.1.1 Advantages The advantage of physical removal of a piece of metal is that very accurate results are possible. B.1.2 Disadvantages The disadvantages of physical removal of a piece of metal are as follows: a) There is a danger of sample contamination (from the cutting tool or otherwise). b) There is a potential for sample mix up. c) It could weaken parent material. d) It could be t
