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1、 DL 500792Book Number: 15120.6853Price: 3.60 yuanElectric Power Industry Standard of PRC. DLP DL 500792Technical Code for Electrical Power Construction and Inspection(Welding )984917.Issued on Dec31, 1991. Implemented from Sep1, 1992Issued by Ministry of Energy of PRCElectric Power Industry Standard

2、 of PRC DL 500792Technical Code for Electrical Power Construction and Inspection (Welding )Edited by: Power Plant Welding Standardization Technology Committee of the Ministry of EnergyApproved by: Ministry of Energy of PRCIssued on Dec31, 1991. Implemented from Sep1, 1992.Water Conservation and Elec

3、tric Power Publishing House1992 Beijing(Jing) Xindengzi No. 115.Electric Power Industry Standard of PRCTechnical Code for Electrical Power Construction and Inspection (Welding)DL 500792Ministry of Energy of PRCPublished and issued by the Water Conservation and Electric Power Publishing House.(6 Sanl

4、ihe Road, Beijing)Printed by Jingdong House Factory of Beijing.50×1168mm Size 32 2.25 Sheets 57 thousand characters One page of interleafSeptember, 1992, first edition October, 1993, second edition, in BeijingQuantity: 2029140350 volumesBook Number: 15120.6853Price: 3.60 RMBMinistry of Energy o

5、f PRCNotice of issuing of the electric powder industry standard: Technical Code for Electrical Power Construction and Inspection (Welding).Nengyuanji (1991) No.1015To each electric powder administration bureau, electric powder bureau of province, autonomous region and municipality directly under the

6、 Central Government, Electric powder planning institute, Huaneng International Electric Powder Co., electric powder office and hydroelectric power publishing house:In order to adapt to development of welding technology of electric power industry and ensure the erection quality of heat power plant, w

7、e modify Technical Code for Electrical Power Construction and Inspection (Welding) SDJ5182 issued in 1982, the revision number is DL500792, which took effect as of September 1, 1992 when the original code terminated. If you have any questions, please contact the infrastructure construction departmen

8、t of the ministry and edition unit.Dec31, 1991.Contents1. General12. Welders23. Steel Products And Welding Materials54. Preparation For Welding75. Welding Process196. Heat Treatment After Welding247. Quality Inspection278. Quality Standards319. Technical Documents3810. Annex3911. Additional Declarat

9、ion681.General1.01 This code is applicable to welding of boilers, pressure pipelines, pressure vessels and steel structure of thermal power generation equipment of 600MW or below, and design, manufacture, installation and repairs of electric power system of energy industry.1.02 This code is applicab

10、le to manual arc welding, manual tungsten electrode argon arc welding, oxy-acetylene welding, buried arc automatic welding, etc of carbon steel (carbon content 0.35%), common low alloy steel and refractory steel. For the welding methods of other materials, see the technical requirements of this code

11、 and related standards.1.03 Unless otherwise specified in construction contract, the construction and inspection of the thermoelectric generating sets imported from abroad should be carried out according to this code.1.04 Testing of weld quality should be appraised respectively according to operatin

12、g conditions of work pieces and quality requirements.1.05 Testing of metal materials, check of weld junction of equipment, ball-passing test, appraisal of weld process, quality examination of welding joints as well as evaluation of Welders should be performed respectively according to related regula

13、tions.1.06 Regulations about safety, environment protection, fire-protection, etc, must be observed during the course of welding (welding, heat treatment and metal testing).12. Welders2.01 Welders include welding technical personnel, welding quality inspectors, welding inspectors, welders and weldin

14、g heat treatment personnel.2.02 Each enterprise should have special technical chief, responsible for welding, and special quality inspector of welding.Special technical chief, responsible for welding, should be engineer (technician) or higher level technicians with relative high special engineering

15、level and rich experience in welding, who are responsible for welding process and quality management as well as qualification evaluation of Welders, etc.Each enterprise and its competent department should organize training of Welders to improve their technical levels, theoretical level of specialty

16、and management level. Basic requirements on welders and working contentsTechnical personnel of welding(1) Those technical personnel, who first undertake welding technology management, must accept production practice and system training and achieve corresponding qualification through examination befo

17、re they undertake the task.(2) Master general conditions of projects, strictly execute this code, edit welding plans and draft technical measures, work out schemes for training welders and attend the committee for evaluating the technology of welders and participate in technical evaluation of welder

18、s and inspection of management of welding materials.(3) According to the technical measures, communicate with related persons deeply about technology and instruct them and supervise.(4) Organize appraisal of welding process and edit operation instructions of welding.(5) Participate in quality accept

19、ance of main pipes and components.(6) Record, inspect and arrange welding materials, transfer technical documents of project completion and perform technical summarization as well.2.0.3.2 Welding quality inspectors2(1) Welding quality inspectors should have education degree of primary school at leas

20、t and considerable experience as well as technical level. Furthermore, they must pass professional examination and achieve the qualification certificate.(2) Welding quality inspectors are responsible for compiling welding quality acceptance items, signing and issuing testing documents, inspecting, s

21、upervising, accepting and appraising welding projects.(3) Participate in reviewing technical measures, supervise the implementation of technical measures and stop operation against rules and report it to related departments.(4) Accumulate and summarize quality supervision materials, and cooperate wi

22、th persons concerned for transfer of project completion documents.(5) Determine weld to be tested and keep records, urge departments concerned for quality inspection.(6) Check qualification certificates of welders to master their technical conditions. Stop the welders, whose welding operation is oft

23、en unqualified, from continuing welding work, and suggest that the welder technology committee revoke their qualification certificates.2.0.3.3 Welding testers(1) Welding testers must accept professional technical training and achieve corresponding qualification certificates through examination befor

24、e they undertake the task.(2) The non-destructive testing of weld should be performed according to this code and related regulations. The appraisal of testing results must be done by persons on or above level .(3) Testing must be done at the part determined by welding quality inspectors. Prompt test

25、ing, accurate conclusion and prompt feedback must be guaranteed.(4) Welding testers should seriously fill and issue, collate and keep all testing records.(5) For weld with unqualified appearance, refuse to perform non-destructive defect detection testing. Welders(1) Welders must accept training of b

26、asic knowledge and practical operation and achieve welder qualification certificate through SD26388 Examination Regulation of Welding Technology examination.(2) Welders who undertake the welding of components and parts below should pass corresponding item technology examination.a. Pressure steel str

27、ucture: rigid frame of boilers (main upright column and main crossbeam), structure of erecting equipment and roof truss of main workshops.3b. Pipes on heated surface of boilersc. Pressure vessels and pipes with operating pressure larger than 0.1MPa.d. Vessels and transfer pipes of inflammable and ea

28、sy-explosion media (gas, liquid).e. Non-pressure work pieces on pressure work pieces.f. Welded work pieces of components rotating at a high speed.(3) Welders should comply with working process discipline, perform welding according to the given welding process and welding technology measures, observe

29、 strictly this code and detailed regulations of welding process established by the enterprise, furthermore, perform the quality self-checking.(4) Welders should be familiar with the operation instruction before welding, refuse welding when the requirements of operation instruction are not met. Repor

30、t to persons concerned when grave quality problems occur, and should not deal with them without authorization.(5) If qualified welders have stopped welding of the inspected components for more than 6 months, they must pass new examination before undertaking the welding of inspected components.(6) Qu

31、alified welders should not do the work beyond their qualifications. Heat treatment personnel of welding(1) Heat treatment personnel of welding must accept professional training and pass qualification certificates through examination.(2) Observe this code and welding technology measures as well as he

32、at treatment regulations of operation instruction of welding to realize correct operation and accurate recording.(3) Perform self-check after heat treatment, and accumulate and collate heat treatment materials.43 Steel Products And Weld Materials Know the steel number of welding materials before wel

33、ding to choose corresponding welding materials and determine proper welding process and heat treatment process.3.0.2 The steel products must accord with national standards (standards issued by the ministry concerned, special technical conditions), and the imported steel products must accord with nat

34、ional standards of the exporting country as well as the technical condition specified in contracts. Chemical compositions, mechanical performance and reference datum of steel products, used by power plant, are shown as Annex A.3.0.3 Quality of welding materials welding rod, welding wire, tungsten ro

35、d, argon gas, oxygen, acetylene gas (calcium carbide) and weld flux must accord with national standards (or related ones). Chemical compositions and mechanical performance of welding rod and welding wire, used by power plant, are shown as Annex B and C.3.0.4 There should be quality certificates, pro

36、vided by manufacturers, for steel products, welding rod and welding wire, etc. when the certificates are not given or there are doubts about the quality, spot checks must be done according to the batch number, only the acceptable can be used.3.0.5 Selection of welding rod and welding wire should be

37、performed according to chemical compositions and mechanical performance of matrix as well as the crack resistance, carbon diffusion, pre-heat (before welding) and heat treatment (after welding) of welded joints. When steel products of same types are welded, selection of welding rod (welding wire) sh

38、ould accord with requirements as follows:(1) Metal performance and chemical compositions of weld should be equivalent to matrix.(2) Excellent process performance.3.0.5.2 When steel products of different types are welded, selection of welding rod (welding wire) should accord with requirements as foll

39、ows:(1) When steel products on both sides are not austenite stainless steel, welding rod (welding wire), with compositions between those of steel products on both sides or matching the side of lower alloy content, can be selected.(2) When steel products on one side are austenite stainless steel, sta

40、inless steel welding rod with relatively high content of nickel can be used.For the recommended values of welding rod (welding wire), for welding steel of different types, and heat treatment temperature after welding, see Annex E.5 Cerium-tungsten bar should be used for electric pole of tungsten ele

41、ctrode argon-arc welding, purity of argon gas should not be lower than 99.95%.3.0.7 Purity of oxygen, used for oxy acetylene welding, must be higher than 98.5%, and the purity of acetylene gas should accord with GB681986 Dissolved Acetylene. If acetylene gas is made from calcium carbide, it must hav

42、e a factory certificate and the quality can be tested by determining the content of sulfur and phosphor (according to standards of welded metal); the acetylene gas used for welding must be filtered, and calcium carbide which is not checked or has a high content of impurity should not be used for wel

43、ding of the tested components.3.0.8 Weld flux used for automatic welding of buried arc must accord with related standards, and common weld flux of buried arc welding are shown as Annex D.64 Preparation for Welding4.0.1 Location of weld junction should avoid stress concentration zone and facilitate w

44、elding and heat treatment requirements below should be generally met. Center line of welding junction of pipes on heated surface of boilers should be at least 70mm away from curvature point of pipes or external wall of steam drum, headers and the edge of support and hanger, the space between two but

45、t-joint weld junctions should not be less than 150mm.4.0.1.2 Distance between center line of butt-joint weld junction of pipes and curvature point of pipes should not be less than external diameter of pipes or 100mm (except welded, forged and cast pipes) and is at least 50mm away from the edge of su

46、pport and hanger, the space between two butt-joint weld junction should not be less than diameter of the pipe or 150mm.4.0.1.3 Pipe connection and instrument sockets should not be set in weld and heat-affected areas. Center line of butt-joint weld junction of pipe body should not be less than wall t

47、hickness plus 15 away from curvature point of closure head or 25mm and not larger than 50mm.4.0.1.5 For the pipe body and closure head with lengthwise weld, distance between two adjacent lengthwise weld should be larger than three times wall thickness and not less than 100mm.4.0.1.6 Pipe holes of we

48、ld pipes should avoid weld to prevent that heat affected areas of pipe hole weld and adjacent weld overlap. When it is necessary to drill holes on or near weld, requirements below should be met.(1)If the weld is located on both sides of pipe hole and larger than hole diameter and is not less than 60

49、mm, requirements of item 8.0.2 should be met, and it should be tested qualified through non-destructive defect detection.(2)Edges of holes are not on weld defects.(3)Heat treatment, after welding, should be done for pipe connection to eliminate stress.4.0.1.7 Lapping size of lap weld should not be l

50、ess than five times thickness of matrix or 30mm.4.0.2 Patterns of bevel of pipes, pipes, pressure vessels and steel structure should be made according to the design drawing. If there are no specific regulations, patterns and sizes of bevels must guarantee welding quality, small amounts of added meta

51、l, working condition improvement, easy operation, reducing welding stress and deformation and meeting defect detection requirements, etc.7For basic patterns and sizes of weld joints, see table 4.0.2.4.0.3 Weldment laying-off and bevel machining should be performed according to requirements as follow

52、s:4.0.3.1 Mechanical methods should be employed for weldment laying-off, especially for alloy steel products of great hardening ability, pipes with nominal diameter less than 100mm and soda water pipes with nominal diameter larger than 100mm and working pressure greater than 3.9MPa.4.0.3.2 When heat

53、-processing method (e.g. flame cutting) is used for laying-off, machining allowance should be reserved at the cut to remove quench hardening layer and superheat metal. For alloy steel products of great hardening ability, after laying-off is completed with heat processing method, annealing treatment

54、must be done for the cut before further processing.4.0.3.3 Bevels should be prepared with mechanical processing method. If flame-cutting method is employed to obtain bevels, oxide, clinker and spatter, on surface of the cut, should be removed according to 4.0.5, furthermore, the uneven area should b

55、e leveled.4.0.4 Weldment should be tested according to requirements below after laying-off and bevel machining. If qualified, it can be grouped.(1)For steel products of great hardening ability, if flame-cutting method is used for the bevel laying-off, the processed surface should be qualified after

56、defect detection test.(2)No defects, such as cracks, double skin, bevel damage or bur, etc, are at the bevel.(3)The machining size of bevel should accord with drawings.(4)No cracks or interlayer, etc within the cleaning range specified in 4.0.5.4.0.5 Oil, paint, sludge and rust, etc on external or i

57、nner walls of matrix on or near weld junction of weldment should be cleaned before assembly until there is metal luster. The cleaning range is as follows:(1)Manual butt-joint weld junction of arc welding: 1015mm on each side.(2)Buried arc weld junction: 20mm on each side.(3)Angle joint weld junction: weld leg K value plus 10mm.4.0.6 End face of butt joint pipe mouth should be vertical to ce