SANS 10268-10-2009 Welding of thermoplastics - Welding processes Part 10 Weld defects《热塑性塑料的焊接 焊接过程 第10部分：焊接缺陷》.pdf

1、 Collection of SANS standards in electronic format (PDF) 1. Copyright This standard is available to staff members of companies that have subscribed to the complete collection of SANS standards in accordance with a formal copyright agreement. This document may reside on a CENTRAL FILE SERVER or INTRA

2、NET SYSTEM only. Unless specific permission has been granted, this document MAY NOT be sent or given to staff members from other companies or organizations. Doing so would constitute a VIOLATION of SABS copyright rules. 2. Indemnity The South African Bureau of Standards accepts no liability for any

3、damage whatsoever than may result from the use of this material or the information contain therein, irrespective of the cause and quantum thereof. ISBN 978-0-626-22682-4 SANS 10268-10:2009Edition 1.3SOUTH AFRICAN NATIONAL STANDARD Welding of thermoplastics Welding processes Part 10: Weld defects Pub

4、lished by SABS Standards Division 1 Dr Lategan Road Groenkloof Private Bag X191 Pretoria 0001Tel: 012 428 7911 Fax: 012 344 1568 www.sabs.co.za SABS SANS 10268-10:2009 Edition 1.3 Table of changes Change No. Date Scope Amdt 1 2002 Amended to be aligned with international specifications for polyethyl

5、ene pipes, to update referenced standards, and to replace withdrawn referenced standards. Amdt 2 2005 Amended to change the designation of SABS standards to SANS standards, to update the list of parts in the foreword, to correct mathematical and other symbols in table 2 (fault 8), table 5 (fault 4),

6、 table 9 (faults 7 and 10) and table 12 (fault 6), and to add footnote numbers in table 2 and annex A. Amdt 3 2009 Amended to update the referenced standards. Acknowledgement The SABS Standards Division wishes to acknowledge the valuable assistance derived from publications of the Deutscher Verband

7、fr Schweisstechnik (German Welding Engineering Association). Foreword This South African standard was approved by SABS TC 1041, Welding of thermoplastics, in accordance with procedures of the SABS Standards Division, in compliance with annex 3 of the WTO/TBT agreement. This document was published in

8、 August 2009. This document supersedes SANS 10268-10:2005 (edition 1.2). A vertical line in the margin shows where the text has been technically modified by amendment No. 3. SANS 10268 consists of the following parts, under the general title Welding of thermoplastics Welding processes: Part 1: Heate

9、d-tool welding. Part 2: Electrofusion welding. Part 3: Hot-gas welding. Part 4: Hot-gas extrusion welding. Part 5: Solvent welding. Part 6: Ultrasonic welding, staking and insertion. Amdt 2 Part 10: Weld defects. This list is not exhaustive and other parts are still under consideration. Annexes A an

10、d B are for information only. SANS 10268-10:2009 Edition 1.3 1 Contents Page Acknowledgement Foreword 1 Scope . 3 2 Normative references . 3 3 Definitions 4 4 Requirements . 4 5 Materials . 5 6 Assessment classes 6 7 Acceptance of components or systems . 7 8 Assessment tables . 8 Annex A (informativ

11、e) Allowable welding bead width with heating elements for butt welds on PE and PP pipes . 28 Annex B (informative) Bibliography 29 SANS 10268-10:2009 Edition 1.3 2 This page is intentionally left blank SANS 10268-10:2009 Edition 1.3 3 Welding of thermoplastics Welding processes Part 10: Weld defects

12、 1 Scope This part of SANS 10268 describes various defects that could occur during the following welding processes: heated-tool butt welding (HS); heated-tool socket welding (HD); electrofusion welding (HM); hot-gas welding with torch separate from filler rod (WF); hot-gas string-bead welding (WZ);

13、and hot-gas extrusion welding (WE). It also covers the causes of the defects encountered and the assessment class requirements for welds made by means of the above welding processes. 2 Normative references The following standards contain provisions which, through reference in this text, constitute p

14、rovisions of this part of SANS 10268. All standards are subject to revision and, since any reference to a standard is deemed to be a reference to the latest edition of that standard, parties to agreements based on this part of SANS 10268 are encouraged to take steps to ensure the use of the most rec

15、ent editions of the standards indicated below. Information on currently valid national and international standards can be obtained from the SABS Standards Divison. DIN 32 502, Imperfections in plastic welded joints B Classification, terminology. Amdt 3 SANS 791, Unplasticized poly(vinyl chloride) (P

16、VC-U) sewer and drain pipes and pipe fittings. SANS 966-1, Components of pressure pipe systems Part 1: Unplasticized poly(vinyl chloride) (PVC-U) pressure pipe systems. Amdt 1 SANS 967, Unplasticized poly(vinyl chloride) (PVC-U) soil, waste and vent pipes and pipe fittings. SANS 1315, Polypropylene

17、pressure pipes. Amdt 3 SANS 10268-10:2009 Edition 1.3 4 SANS 4427/ISO 4427 (SABS ISO 4427), Polyethylene (PE) pipes for water supply Specifications.Amdt 3 SANS 4427-3 /ISO 4427-3, Plastics piping systems Polyethylene (PE) pipes and fittings for water supply Part 3: Fittings. Amdt 3 SANS 6269, Weldin

18、g of thermoplastics Test methods for welded joints. SANS 10112, The installation of polyethylene and poly(vinyl chloride) (PVC-U and PVC-M) pipes. SANS 10268-1, Welding of thermoplastics Welding processes Part 1: Heated-tool welding. SANS 15874-3/ISO 15874-3, Plastics piping systems for hot and cold

19、 water installations Polypropylene (PP) Part 3: Fittings. Amdt 3 3 Definitions For the purposes of this part of SANS 10268, the applicable definitions given in SANS 10268-1 and the following definitions apply: 3.1 assessment class a quality rating, i.e. I, II or III, that indicates the suitability o

20、f a welded joint for a given level of service severity, and that consists of a specific set of requirements for each of the welding methods covered by this part of SANS 10268, with regard to the occurrence and extent of possible weld defects (See also table 1.) NOTE 1 This part of SANS 10268 uses th

21、ree assessment classes, with class I representing suitability for the most severe conditions (see table 1). NOTE 2 The allocation of a given welded plastics requirement or installation to a particular assessment class depends critically on the actual site and service conditions (see 6.2) and is not

22、covered by this part of SANS 10268. 3.2 defect any imperfection in a weld joint Amdt 3 4 Requirements 4.1 Welded joints Requirements for welded joints shall be specified in any documentation that can be binding on the manufacturer, for example, working drawings or welded diagrams. As a rule it shoul

23、d be sufficient to identify a weld as per the following example: WZ-V-II where WZ is the welding process; V is the welding symbol and measurements; and II is the evaluation group code. If the tables contained in this part of SANS 10268 are used, the requirements for assessing a welded joint with res

24、pect to a particular quality class can be readily determined. By checking SANS 10268-10:2009 Edition 1.3 5 systematically through individual features (i.e. the type and extent of the faults), it is possible to undertake the evaluation of the welded joints as part of the acceptance procedure for the

25、welded component or system. 4.2 Weld characteristics The requirements for weld characteristics should cover all additional data such as: a) deformation resistance, for example, the welding factor; b) plasticity, for example, bending angle or cracking; and c) resistance to chemical attack, i.e. the r

26、esistance factor. 4.3 Aftertreatment In certain cases, it might be necessary to apply a finishing process, such as machining, to the completed weld joint. This could be required where dynamic stresses occur to ensure notch-free transitions, and also: a) to smooth weld surfaces (for example, tank lin

27、ings); b) to improve flow behaviour (for example, removal of internal weld beads in pipes); and c) for technical inspection reasons. In such cases it is advisable that the weld be tested and evaluated both before and after machining. 4.4 Examination and testing Visual examination and testing of weld

28、ed joints shall comply with the requirements of SANS 6269. 5 Materials 5.1 This part of SANS 10268 applies to welded joints on components and systems made from the following materials: a) high-density polyethylene (PE-HD) (also known as rigid PE); b) polypropylene block copolymer (PP-B); c) polyprop

29、ylene homopolymer (PP-H); d) polypropylene random copolymer (PP-R); e) chlorinated poly(vinyl chloride) (PVC-C); f) high-impact poly(vinyl chloride) (PVC-HI); g) unplasticized poly(vinyl chloride) (PVC-U) (also known as rigid PVC); h) polyvinylidenefluoride (PVDF); and i) acrylonitrile butadiene sty

30、rene terpolymer (ABS). SANS 10268-10:2009 Edition 1.3 6 5.2 The use of this part of SANS 10268 for the approval or rejection of welds made on thermoplastics other than those listed in 5.1 shall be agreed upon between the manufacturer and the purchaser. 6 Assessment classes 6.1 Classification Specifi

31、c requirements for load-carrying capacity and the safety requirements for the commodity being carried by the welded joints in various piping systems are given in SANS 791, SANS 966-1, SANS 967, SANS 15874-3, SANS 4427-3 and SANS 10112. Amdt 1; amdt 3 The following table of assessment classes shall b

32、e used as a basis for designers, manufacturers and inspectors, to be able to determine the measures required for the necessary quality control of the welding processes. Table 1 Measures required for quality control 1 2 Assessment class Requirement level I High requirements for safety or for load-car

33、rying capacity, or for both II Medium requirements for safety or for load-carrying capacity, or for both III Low requirements for safety or for load-carrying capacity, or for both 6.2 Criteria for allocation of assessment class When requirements for specific welded joints are drawn up, they should b

34、e appropriate for the local situation or the specific application (i.e. cognizance should be taken of the commodity to be conveyed). In the allocation of assessment classes, the following factors shall be considered: a) the type of stress to which the system will be subjected during operation (for e

35、xample, static or dynamic); b) the material to be welded (for example, viscous or brittle); c) the operating conditions under which the system will work (for example, static or changing); d) the production site and conditions (for example, workshop, construction site or welding position); and e) the

36、 potential danger presented by the commodity to be conveyed (for example, gases, fluids that are dangerous when mixed with water, etc.). 6.3 Assessment The test results obtained in accordance with 4.4 shall form the basis for the classification of welded joints into one of the three assessment class

37、es in accordance with the appropriate table supplied in this part of SANS 10268. These results shall be used to determine points where the requirements SANS 10268-10:2009 Edition 1.3 7 are not complied with. Should the component or welded joint not correspond to the assessment class specified, then

38、it will be deemed to be a reject. (See also 6.4.) 6.4 Overlapping faults Should two or more types of faults occur simultaneously in a welded joint, the detrimental effect that each individual fault has on the weld could be increased systematically. Tests should then be carried out to ascertain wheth

39、er the welded joint still meets the requirements specified or whether restrictions should be placed on the component or on the assembled system with regard to safety and quality standards. In certain circumstances, the component or system might have to be re-classified into another assessment class,

40、 depending upon mutual agreement between the manufacturer and the purchaser. 7 Acceptance of components or systems If tests on a component or system confirm that the requirements specified have been met, the component or system shall be deemed to comply with the requirements. Where the requirements

41、are not met, and corrective action is not possible, the manufacturer shall produce a special document that specifies the usability of the component or system in comparison with the requirements of the original specification. In this case, acceptance or rejection shall be as agreed upon between the m

42、anufacturer and the purchaser. SANS 10268-10:2009 Edition 1.3 8 8 Assessment tables Table 2 Description of assessment classes for heated-tool butt welding (HS) External quality of joint 1 2 3 4 5 Assessment class Type of fault Description I II III Cracks running length-wise or crosswise to weld, and

43、 located: 1 Cracks in the weld; in the base material; or in the heat-affected zone Not permissible Not permissible Not permissible Continuous or local notches lengthwise to weld with notch root in base material, caused, for example, by: 2 Bead notches insufficient joint pressure; warming-up time too

44、 short; or cooling time too short Not permissible Not permissible Not permissible Notches in the edge of the base material, lengthwise or crosswise to weld, caused, for example, by: 3 Notches and flutes clamping tools; incorrect transport; or faulty edge preparation Locally permis-sible if ending of

45、 notch is flat and s 0,7 b2Permissible if b1 0,6 b2Permissible if b1 0,5 b29 Thermal damage High-gloss bead face with voids or nodules, usually associated with faulty reinforcement formation and marked bead notches Not permissible Not permissible Not permissible 1) Description and evaluation as per

46、current state of knowledge of polyolefins. Amendments might be required after revision of DVS 2207-1. 2) Applies only to welds which are produced using equipment which complies with the requirements of SANS 1671-1, Welding of thermoplastics Machines and equipment Part 1: Heated-tool welding. Amdt 1;

47、 amdt 2SANS 10268-10:2009 Edition 1.3 10 Table 3 Description of evaluation groups for heated-tool butt welding (HS) Internal quality of joint 1 2 3 4 5 Assessment class Type of fault Description I II III No fusion or incomplete fusion on joint faces, over part or whole of weld cross-section, caused,

48、 for example, by: 1 Lack of fusion contaminated joint faces; oxidized joint faces; excessive reversal time; or heated-tool temperature too low Not permissible Not permissible Not permissible Hollow space in joint planes, caused, for example, by: 2 Blowhole insufficient joint pressure; or insufficien

49、t cooling time Not permissible Not permissible Not permissible Numerous, dispersed, isolated or locally concentrated pores or inclusions, caused, for example, by: 3 Pores caused by inclusions of foreign matter water vapour or gas formation during welding; or contaminated heated tool Small isolated pores permissible if s 0 Locally permis-sible if k 0 Notches in base material along weld, caused, for example, by: 3 Edge notches penetration of welding nozzle edge; machining of weld; or unsatisfactory