焊接工艺评定规程DLT 868-2004 (英文版)

ICS 03.100.30 J33 DL Electric Power Industry Profession Standard of the People’s Republic of China DL/T 868-2004 Supersedes SD 340-1989 Code for Welding Process Qualification DL/T 868-2004 Issued date :2004-03-23 Implementation date :June 1, 2004 Issued by State Development and Reform Commission, China Contents Foreword 1 Coverage 2 Normative Reference Documents 3 Terminology 4 General Rules 5 Basic Regulations 6 Qualification Items and Test Specimen Preparation 7 Test Methods and Qualification Criteria 8 Procedure and Management of Qualification Work Annex A (Informative Annex) Classification of Common Foreign Steel Materials Annex B (Informative Annex) Format of Welding Process Qualification Prospectus, Scheme and Report Foreword According to requirement by Notification on Confirmation of plan for 1999’ Electric Power Industrial Standard Development and revision issued by State Economy and Trade Commission, SD340-1989 Code for Welding Process Qualification of Boilers and Pressure Vessels in Heat Power Plants are revised, whose format is arranged as per DL/T600-2001 Basic Regulations for Compilation of Electric Power Industrial Standards. In the standard revision, related international standards, state standards and related domestic and regulations are referenced. In order to correctly perform welding works involved in production, construction, inspection and repair, and reformation in electric power industry, welding process guide documents must be set up by following specified procedures. The standard provides criteria for welding process qualification to be completed before welding process guide documents are drafted. Basic standards used in welding jobs in electric power industry are DL/T 869-2004 Welding Technology Code for Heat Power Plants and DL/T6578-1999 General Specification for Steel Structure Welding in Electric Power Stations. The standard is a relatively independent one to support said standards. The original code has been implemented for more than 10 years, promoting welding technology development in electric power industry, playing a very good role to improve welding work quality. As technologies advance, the code showed some inadaptability. The revision mainly expands applicable coverage of welding methods, increases new steel brands used in electric power stations during recent years: improperly complicated procedure and contents in the original code are adjusted. The standard becomes effective and supersedes SD340-1989 Code for Welding Process Qualification of Boilers and Pressure Vessels in Heat Power Plants, covers all welding process qualification work in electric power industry. The standard becomes effective and supersedes SD340-1989. Annex A and B to the standard are informative annexes. The standard is presented by China Association of Electric Power Enterprises. The standard shall be centrally managed and interpreted by Welding Standardization Committee for Electric Power Stations in Electric Power Industry. The standard is drafted by Electric Power Construction Research Institute and Power Supply Department under State Power Co., Liaoning Power Plant, Liaoning Electric Power Science Research Institute, and Tianjin Electric Power Construction Co. The standard is specifically drafted by Guo Jun, Yang Jianping, Li Weidong, Zhang Peiliang, Zhang Xinlin and Liu Chuanyu. Code for Welding Process Qualification 1 Coverage The standard specifies rules, test methods and certified standard for welding process qualification (qualification for short hereafter) performed before fabrication, installation and repair welding jobs of steel equipment, such as boilers, pipelines, pressure vessels and load bearing structures in electric power industry and welder skill examination are implemented. The standard applies to welding process qualification of welding methods, such as electrode arc welding, tungsten electrode argon arc welding, fusion electrode gas protection welding, core wire electric arc welding, gas welding and hidden arc welding. 2 Normative Reference Documents Clauses contained in the following documents are referred by the standard and become clauses of the standard. Any reference document with date indicated and their subsequent modification sheets (excluding error corrections) or revised editions do not apply to the standard, however, all parties who enter into an agreement based on the standard are encouraged to probe into possibility of use of the latest editions of such documents. For any reference document without date indicated, their latest editions are applicable to the standard. GB/T 228-2002 Metal Materials Method for Tensile Tests under Ambient temperature GB/T 229 Method for Metal Sharpe Notch Impact Test GB/T 231.1 Metal Brinell Hardness Test Part I: Testing method GB 713 Steel Sheets for Boilers GB/T 983 Stainless Steel Welding Electrodes GB/T 1220 Stainless Steel Rods GB/T1221 Heat Resisting Steel Rods GB/T 1591 Low Alloy High Strength Structure Steels GB/T 2649 Sampling Method for Mechanical Property Test of Welding Joints GB/T 2650 Method for Welding Joint Impact Test GB/T 2651 Method for Welding Joint Tensile Test GB/T 2653 Method for Welding Joint bending and Crushing Test GB/T 2654 Method for Welding Joint and Built-up Welding Metal Hardness Test GB/T 3077 Alloy Structure Steels GB/T 3087 Seamless Steel Tubes for Low and Middle Pressure Boilers GB/T 3274 Carbon Structure Steels and Low Alloy Structure Steels Hot Rolled Thick Steel Plates and Strips GB/T 3280 Cold Rolled Stainless Steel Sheets GB/T 3323 Radiography and Quality Classification of Steel fusion butt welding joints GB/T 4237 Hot Rolled Stainless Steel Sheets GB/T 5117 Carbon Steel Welding Electrodes GB/T 5118 Low Alloy Steel Welding Electrodes GB/T 5293-1999 Carbon Steel Welding Wires and Fluxes for Hidden Arc Welding GB 5130 Seamless Steel Tubes for High Pressure Boilers GB 6479 Seamless Steel Tubes for High Pressure Chemical Fertilizer Plants GB 6654 Steel Sheets for Pressure Vessels GB/T 8110 Carbon Steel and low Alloy Steel Welding Wires for gas Shield Arc Welding GB/T 10045 Carbon Steel Flux-Cored Wires GB/T 12470 Fluxes for Low Alloy Steel Hidden Arc Welding GB/T 14958 Steel Wires for Gas Shield Welding DL/T 678 General Specification for Welding Steel Structures in Power Stations DL/T 679 Procedure for Welder Skill Examination DL/T 752 Welding Process Procedure for Dissimilar Steels in Heat Power Plants Dl/T 821 Radiographic Inspection Technology Procedure for Steel Pressure Pipeline Butt Welding Joints DL/T 819 Technological Procedure for Welding Heat Treatment in Heat Power Plants DL/T 869-2004 Technological Procedure for Welding in Heat Power Plants JB 4726 Carbon Steel and Low Alloy Steel Forgings for Pressure Vessels JB 4728 Stainless Steel Forgings for Pressure Vessels JB 4730 Non-Destructive Test of Pressure Vessels JB/T 10087 Technical Specification for Pressure Steel Castings of Steam Turbines YB(T) 32 Cold Drawn Seamless Steel Tubes for High Pressure Boilers YB(T) 40 Thick Carbon Steel and Low Alloy Steel Sheets for Pressure Vessels YB(T) 41 Thick Carbon Steel and Low Alloy Steel Sheets for Boilers (1984) DJH Doc. No. 146 Guides to Metallographic Examination in Electric Power Construction by Ministry of Water Conservancy and Electric Power Industry, China, Nov. 14, 1984 3 Terminology Following terms are applicable to the standard. 3.1 Welding Process Qualification (Qualification for short) Test process and result evaluation performed to verify correctness of welding process parameter to be drawn up. Qualification parameters are classified as: a) Primary parameters, referring to welding conditions affecting mechanical properties of welding joints (except impact toughness); b) Additional primary parameters, referring to welding conditions affecting impact toughness of welding joints; c) Secondary parameters, referring to welding conditions not affecting mechanical properties of welding joints. 3.2 Welding Joint of Dissimilar Steels Welding joints formed between steels with dissimilar metallographic structures, including commonly welding joints between austenitic steel, martensite steel, bainite steel and pearlite steel. 3.3 Test Piece Welding piece manufactured as per pre-defined welding process for welding process qualification test. A test piece contains two parts, i.e., mother metal and welding joint. 3.4 Welding Piece Component connected by welding process. 3.5 Test Specimen Standard specimen or non- standard specimen prepared for tests according to related standards. 3.6 Transverse Bend Bends with welding seam axis vertical to longitudinal axis of test specimen. 3.7 Longitudinal Bend Bends with welding seam axis parallel to longitudinal axis of test specimen. 3.8 Face Bend Bends with front face of welding seam being pulled face of test specimen. Face with larger welding seam width is called front face; when widths of welding seams on both sides are equal, the side on which face-covered welding seam is completed first is called front face. 3.9 Back bend Bends with back face of welding seam being pulled face of test specimen. 3.10 Side Bend Bends with cross section of welding seam being pulled face of test specimen. 4 General Rules 4.1 Before components specified in Article 1 are welded, welding contractor shall check up whether or not there is any qualification information. If not or coverage of present information does not comply with said welding project, qualification must be examined. 4.2 Qualification shall be evaluated according to reliable steel welding properties and performed as per the standard before formal welding is conducted. Information data to be used for welding property qualification evaluation shall be provided by steel supplier or collected by welding contractor. Data to support steel welding property qualification include technical parameters of steel, report on steel welding crack sensitivity test, research report, report on strain corrosion test, public related theses public related summaries of welding works, etc. 4.3 Steels and welding materials for qualification assessment shall carry factory certificates and conform to corresponding standards. If there is any doubt, major elements shall be re-checked and mechanical property tests shall be performed. 4.4 Welding equipment and tools for qualification assessment shall be under normal operating conditions, parameter recording instruments and gas flow meter, etc. shall be calibrated. 4.5 Standard for welding process qualification shall meet regulations in product specification. If qualified standard is not specified in product specification, then tests shall include mechanical test, bending tests and other tests specified in product specification, and their qualified standard shall follow the standard. In test process, artificial factors shall be removed, and welding process is regarded qualified if each test item is qualified. 4.6 Persons who preside qualification evaluation and who comprehensively assess test results shall be welding engineers. Operators who perform test specimen inspection and test shall meet related regulations in DL/T 869. 4.7 Information data to complete qualification assessment shall be summarized and qualification results shall be confirmed by welding engineers. 4.8 Qualification information data shall be filed and kept. 4.9 Qualification information data reviewed and approved may be generally used within the same quality management system. 5 Basic Regulations 5.1 Qualification parameters Classes and contents of qualification parameters of different welding methods refer to Form 5.2 Principles for Re-qualification 5.2.1 Re-qualification shall be carried out when primary parameters change or primary parameters exceed applicable coverage specified by the standard. 5.2.2 When primary parameters have been qualified, for welding pieces required for impact toughness test, only impact toughness test on supplementary test pieces welded under conditions original primary parameters are applicable to. 5.2.3 When secondary parameters alter, only welding process (job) guide book is needed to revise, but re-qualification is not necessary. 5.3 Welding Methods 5.3.1 Different welding methods shall be qualified separately, not qualified mutually for each other. 5.3.2 If combination of more than one welding method is evaluated for qualification, each welding method may be evaluated for qualification separately or in combined form. When each welding method is applied separately or in combined form, metal thickness of welding seam is effective within their own applicable range of qualified thickness. 5.4 Steel Materials 5.4.1 Steel classes and grades are specifies as follows: a) Common domestic steel classes and grades refer to Form 2; b) Common foreign steel classes and grades refer to Annex A, which may be treated equally as corresponding domestic steel classes; c) Steels not listed in forms may, if similar to a steel brand in Form 2 or Annex A in terms of their chemical composition, structure types mechanical properties and welding characteristics, be listed into corresponding class for qualification. 5.4.2 Steels to be used for the first time must be evaluated for qualification. Form 1 Primary Parameters, Additional Primary Parameters and Secondary Parameters of Different Welding Methods Qualification Parameters Primary Parameters( )/ Additional Primary Parameters( )/ Secondary Parameters(O) Class Content Electrode Arc Welding Argon Arc Welding Gas Welding Hidden Arc Welding Gas Shield Welding Flux-Cored Welding Wire Steel Steel Class and Grade Applicable coverage of steel thickness and welding seam metal thickness Applicable coverage of pipe diameters Filler metal added or cancelled Preset or additional filler metal added, cancelled or changed Welding electrode class changed Welding wire class changed Flux class changed Flux-cored wire changed to solid-cored wire or vice versa Constituents of welding material and deposited metal Welding seam metal thickness exceeding applicable coverage Combustible gas type and its ratio changed Shied gas type and its ratio changed Gas flow exceeding qualification value Root side shied gas added or cancelled Basic electrode changed to acid electrode Back plate added or cancelled Filling material designation changed Flux grain size altered Tungsten electrode type or diameter altered Groove or dimension altered Groove root intermittent or root face altered Welding position Welding position altered Applicable range of pre-heat temperature exceeded More than 50oC of interlayer temperature changed Post-welding heat treatment added or cancelled Teat treatment specification parameters changed Pre-heat and post-welding heat treatment Interval time between welding completion and heat treatment Heat input quantity range exceeded Fusion droplets transited from short-circuit form to other form, or vice versa Electrical Characteristics Power supply type or polarity changed Distance from auto welding electrode nozzle to work piece changed Welding speed variation range 10% more than qualification value Jet nozzle size changed Form 1 (Cont’d) Qualification Parameters Primary Parameters( )/ Additional Primary Parameters( )/ Secondary Parameters(O) Class Content Electrode Arc Welding Argon Arc Welding Gas Welding Hidden Arc Welding Gas Shield Welding Flux-Cored Welding Wire Leftward welding changed to rightward welding or vice versa Sing amplitude, frequency and dwell time at both ends changed Pre-welding, root and interlayer cleaning methods changed Welding Process Multi-pass welding changed to single-pass welding on each side With or without welding seam hammered Single welding wire changed to multiple welding wires or vice versa Single-sided welding changed to double sided welding or vice versa Flame nature changed Vertically upward welding changed to Vertically downward welding Hand welding changed to automatic welding (semi-automatic welding), or vice versa Form 2 Common Domestic Steel Classes and Grades Class and Grade Class Code Grade Code Steel Brand Corresponding Standard No. Carbon steel and plain low alloy steel A Carbon steel (carbon content ) I Plain low alloy steel 1) (Re ) II Plain alloy steel (Re ) Form 2 (Cont’d) Class and Grade Class Code Grade Class Steel Brand Code Corresponding Standard No. Grade Pearlite steel I Bainite steel II Heat Resistant High Strength Steel and Alloy Structure Steel B Martensite steel III Martensite I Ferrite II Stainless Steel C Austenite III 1) Based on regulations in GB/T 228-2002, original metal mechanical property index yield limit( s) is re-defined . The symbol for newly defined yield strength is Rs. 5.4.3 Replacement Principles for Steel Class A and B Application a) For welding of the same steel and qualification of steels of the class and same grade, steel with higher alloy content may replace steel with lower alloy content, not vice versa. b) For welding of the same steel, with steels of the same class but different grades, qualification for higher grade steel applies to qualification for lower grade steel. c) For welding of steels of the same class but different grades, refer to Form 3 for applicable coverage of specific welding processes. d) Welding joints of dissimilar steels Class BIII and Class A and B formed shall be assessed for qualification separately. 5.4.4 Steel Class C shall be qualified separately according to their grades, never substituted with each other, whose joints with steel Class B and A shall be all qualified separately. Form 3 Applicable Coverage of Qualified Welding Processes Condition for Qualification Applicable Coverage AII and AII Welding joints formed between AII and AII or AI AIII and AIII Welding joints formed between AIII and AIII or AII , AI BI and BI Welding joints formed between BI and BI or AII, AI BII and BII Welding joints formed between BII and BII or BI, AII, AI 5.5 Classes and Welding Seam Types of Test Pieces to be Qualified 5.5.1 Test pieces are divided into three classes, i.e., Plate, Tubular and tubular and plate. 5.5.2 Welding seams are divided into completely penetrated one and partially penetrated one. Qualification for the former shall apply to qualification for the latter, not vice versa. 5.5.3 Welding processes qualified for plate butt welding joint test piece shall apply to tubular butt welding joint and vice versa. 5.5.4 Welding processes qualified for butt welding joint test piece shall apply to fillet welding joint between tube and plate or tube and tube, vice versa. 5.5.5 Welding processes qualified for plate butt welding joint test piece shall apply to fillet welding joint. 5.6 Test Piece Thickness and Welding Piece Thickness 5.6.1 Test piece