T/DASIV 006-2024 核工程用大厚度P91钢管焊条电弧焊焊接工艺规范（英文版）

　　ICS 25.160.10 CCS C3311

　　Group Standard

　　T/DASIV 006—2024 (EN)

　　Specification for shielded metal arc

　　welding of heavy thickness P91 steel

　　for nuclear engineering

　　核工程用大厚度 P91钢管焊条电弧焊

　　焊接工艺规范

　　(English translation)

　　Issue date:2024-05-15 Implementation date:2024-05-16

　　Issued by Development Association of Steel Industry Value Chain

　　in Yangtze River Delta Region

　　T/DASIV 006-2024

　　CONTENTS

　　T/DASIV 006-2024

　　Foreword

　　This document is drafted in accordance with the rules given in the GB/T 1.1-2020

　　Directives for Standardization – Part 1: Rules for Structure and Drafting of Standardization Documents.

　　Appendices A and B are informative.

　　Attention is drawn to the possibility that some contants of this document may involve patents. The issuing organization shall not be held responsible for identifying such

　　patents.

　　This document is proposed and administered by the Development Association of Steel Industry Value Chain in Yangtze River Delta Region, which is also responsible for its

　　interpretation. Users are encouraged to summarize their experiences during application and provide feedback or suggestions to the Standardization Committee of the

　　Association (email: dasiv2020@163.com).

　　Drafting Organizations:

　　Lead organizations: Northeastern University, Nuclear Industry Engineering Research & Design Co., Ltd.

　　Co-lead organizations: Daye Special Steel Co., Ltd., Tongling Science & Technology School.

　　Participating organizations: Jiangsu University, Tianjin University, China Nuclear Industry 23 Construction Co., Ltd.

　　Drafting Committee:

　　Chief Editors: Cong Wang, Yingchao Feng

　　Deputy Editors: Guanghui Liu, Yimin Yang, Jinping Liu

　　Members: Zhengman Gu, Fuhua Li, Ming Zhong, Zhibao Zhu, Yinchuan Cui, Jun Zhang, Shaojie Wu, Cancan Yan, Ke Han, Hongliang Li, Yue Gao, Peng Chen, Xiaodong Zhang, Jingxin Ren, Chuang Wu, Weiguan Zhang, Ji Gao, Yehua Wu.

　　T/DASIV 006-2024

　　Specification for shielded metal arc welding of heavy thickness P91 steel for nuclear engineering

　　1 Scope

　　This document specifies the general and process requirements for shielded metal arc welding (SMAW) of P91 steel pipes used in nuclear engineering.

　　It applies to P91 steel pipes with wall thicknesses from 38 mm to 64 mm.

　　2 Normative References

　　The following documents are indispensable for the application of this document. For dated references, only the edition applies. For undated references, the latest edition (including all amendments) applies.

　　GB/T 985.1 Recommended joint preparation for gas welding, manual metal arc welding, gas-shielded arc welding and beam welding

　　GB/T 3375 Welding terminology

　　GB/T 4842 Argon

　　GB/T 5310 Seamless steel tubes and pipes for high pressure boiler

　　GB/T 25778 Procurement guidelines for welding consumables

　　NB/T 20002.3 Welding code for mechanical components of PWR nuclear islands-Part 3: Welding procedure qualification

　　JB/T 3223 Welding consumables quality management procedures

　　T/CWAN 0009 Welding terminology-fusion welding

　　T/CWAN 0002 Health standard for weld fume in the air of welding shop

　　TSG Z6002 Examination rules for welding operators of special equipment

　　ASME BPVC III 1 NC Rules for Construction of Nuclear Power Plant Components, Division 1, Subsection NC: Class 2 Components

　　ASME BPVC II C Specification for Welding Rods, Electrodes, and Filler Metals

　　ASTM A-335/A-335M Standard Specification for Seamless Ferritic Alloy-Steel Pipe for High-Temperature Service

　　3 Terms and Definitions

　　Terms defined in GB/T 3375 and T/CWAN 0009 apply to this document.

　　4 General Requirements

　　4.1 Personnel

　　4.1.1 Welders shall receive systematic theoretical training and hold valid welding qualification certificates.

　　4.1.2 Heat-treatment personnel shall pass the training and assessment organized by the construction unit.

　　T/DASIV 006-2024

　　4.1.3 A welding consumable administrator is recommended to manage issuing, storage, drying, distribution, and recycling to ensure full traceability.

　　4.2 Equipment

　　4.2.1 Welding and heat-treatment equipment shall meet process requirements and be properly calibrated. Heat-treatment equipment shall have a control accuracy of ±2 ℃ .

　　4.2.2 Measuring instruments (ammeters, voltmeters, thermocouples, thermometers, argon flowmeters, weld gauges, etc.) shall be calibrated and used within their validity period.

　　4.2.3 Drying and insulation facilities shall have reliable temperature and time control functions with proper display systems.

　　4.3 Materials

　　4.3.1 Base materials shall comply with GB/T 5310, ASTM A-335/A-335M, or ASME SA-335/A-335M and be accompanied by valid material certificates.

　　4.3.2 Welding consumables shall comply with ASME BPVC II C. Suppliers shall provide quality certificates in accordance with GB/T 25778, and consumables shall undergo

　　re-inspection before use.

　　4.3.3 Storage and handling of welding consumables shall follow JB/T 3223.

　　4.3.4 Welding consumables shall be free from rust, scale, or oil contamination.

　　4.3.5 Argon shall comply with GB/T 4842 with purity ≥ 99.99%. Bottled argon shall not be used when pressure is below 0.49 MPa.

　　4.4 Welding Environment

　　4.4.1 Welding sites shall be equipped with protection against moisture, rain, snow, and fumes.

　　4.4.2 Cross-drafts inside pipes shall beprevented during welding.

　　4.4.3 Requirements: Relative humidity: ≤60%. Fume concentration: ≤4 mg/m3 (per T/CWAN 0002). Ambient temperature within 1 m of the weld area: ≥5 ℃ . Maximum wind speeds: GTAW ≤2 m/s; SMAW ≤8 m/s.

　　4.5 Welding Procedure Documents

　　4.5.1 Welding Procedure Specifications (WPS) should refer to Appendix A.

　　4.5.2 Welding Records Sheets should refer to Appendix B.

　　5 Welding Procedure Requirements

　　5.1 Groove Preparation

　　5.1.1 Groove forms shall comply with GB/T 985.1. Mechanical machining is preferred.

　　T/DASIV 006-2024

　　Groove angle tolerance: ±1° .

　　5.1.2 The groove surface and 20 mm on both sides shall be ground clean of scale, rust, oil, and other contaminants.

　　5.1.3 Groove surfaces shall undergo penetrant testing (PT) or magnetic particle testing (MT).

　　5.2 Drying of Welding Materials

　　5.2.1 Drying shall follow the manufacturer’s specifications. Avoid rapid heating or cooling that may damage electrode coatings.

　　5.2.2 Electrodes may not be dried more than twice.

　　5.3 Fit-Up and Tacking

　　5.3.1 Forced alignment is prohibited. Welding clamps shall not be used on the pipe surface. Misalignment shall be evenly distributed; internal misalignment shall not exceed 2.5 mm.

　　5.3.2 Temporary welds used for tacking shall be removed mechanically and the surface ground smooth.

　　5.4 Preheating

　　5.4.1 No contaminants shall enter grooves or surfaces. Insulation shall not obstruct welding operations.

　　5.4.2 For GTAW, the preheating temperature shall be 150-200 °C and the interpass temperature 200-250 °C. For SMAW, the preheating temperature shall be 200-250 °C and the interpass temperature 200-300 °C.

　　5.4.3 Preheating shall be continuous with recorded data.

　　5.4.4 Interpass temperature shall not fall below preheat temperature.

　　5.4.5 Thermocouples shall be placed within the heating zone; additional thermocouples shall be positioned near the groove. Heating width on each side shall be at least 4× the workpiece thickness. The recommended schematic diagram for preheating the steel pipe is shown in Figure 1.

　　T/DASIV 006-2024

　　Figure 1. Schematic diagram of preheating

　　5.5 Welding

　　5.5.1 The root pass shall be welded by GTAW. Back purging with argon is required and shall be verified as effective. The root pass shall consist of at least two layers.

　　5.5.2 Heat input shall be controlled and stable. Except for the root and cap passes, heat input deviation shall not exceed ±10%. Maximum heat input: 3.5 kJ/mm. Heat input calculation formula shall follow NB/T 20002.3.

　　5.5.3 For SMAW filling and capping, bead thickness shall not exceed the electrode diameter; bead width shall not exceed three times the electrode diameter.

　　5.5.4 Slag shall be removed after each pass, and the next pass shall only be welded after self-inspection. Weld joints between layers shall be staggered.

　　5.5.5 Each pass shall be completed without interruption whenever possible. If interruption occurs, measures such as post-heating, slow cooling, or insulation shall be applied to prevent cracking. Rewelding shall only proceed after confirming no cracks.

　　5.5.6 If post-heating is applied, it is recommended to heat the weldment to 80–100 °C and hold for 2 h.

　　5.6 Post-weld heat treatment (PWHT)

　　5.6.1 After welding, the weldment shall cooled to 80–100 ℃ , held for 1–2 h, then immediately subjected to PWHT.

　　5.6.2 Medium-frequency induction heating is recommended. Heating and cooling rates shall not exceed 115 ℃/h. Below 300 ℃ , the rates need not be controlled. Cooling to room temperature shall occur within the insulation layer.

　　5.6.3 The heating width shall be not less than 200 mm on each side from the weld center. Insulation width shall be not less than 300 mm on each side from the groove edge,

　　T/DASIV 006-2024

　　and not less than 100 mm wider than the heater installation width. The insulation thickness shall preferably be 40–60 mm. A recommended arrangement of thermocouples for PWHT is shown in Figure 2.

　　5.6.4 The PWHT holding temperature shall be 760 ±10 ℃ , with a holding time of 4–7 h.

　　5.6.5 During preheating, post-heating, and PWHT, operation records shall be made and self-inspection carried out after completion: a) Process parameters shall be within the control range, and for PWHT, the temperature curve shall be recorded. b) Thermocouples shall remain undamaged and in the correct position. c) The heat-treatment record curve shall be consistent with the procedure card.

　　Figure 2. Arrangement diagram of thermocouples for PWHT

　　T/DASIV 006-2024

　　Annex A

　　(Informative)

　　Welding Procedure Specification (WPS)

　　T/DASIV 006-2024

　　Annex B

　　(Informative)

　　Welding Record Sheet