Standard No.:	GB/T 16702.3-2025
English Name:	Design specification for mechanical components in nuclear island of pressurized water reactor nuclear power plants―Part 3: Class 2 components
Chinese Name:	压水堆核电厂核岛机械设备设计规范第3部分：2级设备
Professional Classification:	GB    National Standard
Source Content Issued by:	SAMR; SAC
Issued on:	2025-02-28
Implemented on:	2025-2-28
Status:	valid
Superseding:	GB/T 16702-2019 Design code for mechanical components in nuclear island of pressurized water reactor nuclear power plants
Target Language:	English
File Format:	PDF
Word Count:	147500 words
Translation Price(USD):	4425.0
Delivery:	via email in 1~5 business day

GB/T 16702.3-2025 Design specification for mechanical components in nuclear island of pressurized water reactor nuclear power plants―Part 3: Class 2 components English, Anglais, Englisch, Inglés, えいご This is a draft translation for reference among interesting stakeholders. The finalized translation (passing through draft translation, self-check, revision and verification) will be delivered upon being ordered. ICS 27.120. 20 CCS F 69 National Standards of the People's Republic of China GB/T 16702.3-2025 Partially replaces GB/T 16702-2019 Design specification for mechanical components in nuclear island of pressurized water reactor nuclear power plants - Part3: Class 2 components 压水堆核电厂核岛机械设备设计规范 第3部分:2级设备 (English Translation) Issue date: 2025-02-28 Implementation date: 2025-02-28 Issued by the State Administration for Market Regulation the Standardization Administration of the People's Republic of China Contents Foreword Introduction 1 Scope 2 Normative references 3 Terms and definitions 4 General rules 5 Material 6 Design 7 Manufacturing and inspection 8 Pressure test 9 Overpressure protection Bibliography Design specification for mechanical components in nuclear island of pressurized water reactor nuclear power plants - Part3: Class 2 components 1 Scope This document specifies the requirements for materials, design, manufacturing, inspection and overpressure protection of Class 2 pressure-bearing equipment in the nuclear island machinery and equipment of PWR nuclear power plant, and describes the corresponding tests. This document is applicable to the design of Class 2 pressure-bearing equipment and its parts specified in Chapter 5 of GB/T 16702.1-2025. 2 Normative references The contents of the following documents constitute the essential provisions of this document through normative references in the text. Among them, for the referenced document with a date, only the version corresponding to that date is applicable to this document; The latest version of the undated referenced document (including all amendments) is applicable to this document. GB/T 150.3-2024 Pressure vessels - Part 3: Design GB/T 151 Heat exchanger GB/T 16702.1-2025 Code for the design of mechanical equipment for nuclear islands in pressurized water reactor nuclear power plants - Part 1: General provisions GB/T 16702.2-2025 Code for the design of mechanical equipment for nuclear islands in pressurized water reactor nuclear power plants - Part 2: Class 1 equipment GB/T 16702.7-2025 Code for design of mechanical equipment for nuclear islands in pressurized water reactor nuclear power plants - Part 7: Equipment support NB/T 20001-2023 Specification for manufacturing machinery and equipment of nuclear island in pressurized water reactor nuclear power plant NB/T 20002.1-2021 Specification for welding machinery and equipment of nuclear islands in pressurized water reactors nuclear power plants - Part 1: General requirements NB/T 20002.5-2013 Specification for welding of nuclear island machinery and equipment in pressurized water reactor nuclear power plants - Part 5: Qualification of manufacturing workshops NB/T 20002.6-2021 Specification for welding of nuclear island machinery and equipment in pressurized water reactor nuclear power plant - Part 6: Product welding NB/T 20002.7 Specification for welding of nuclear island machinery and equipment in pressurized water reactor nuclear power plant - Part 7: Wear-resistant surfacing welding NB/T 20003 Non-destructive testing of nuclear island machinery and equipment in nuclear power plants NB/T 20004 Physical and chemical inspection methods for machinery and equipment materials in nuclear island of nuclear power plants NB/T 20005.1 Carbon steel and low alloy steel for pressurized water reactor nuclear power plants - Part 1: Forged and rolled pieces for class 1, 2 and 3 equipment NB/T 20005.5 Carbon and low alloy steels for pressurized water reactor nuclear power plants - Part 5: Class 1, 2 and 3 pressure-bearing castings NB/T 20005.7 Carbon and low alloy steels for pressurized water reactor nuclear power plants - Part 7: Steel plates for class 1, 2 and 3 equipment NB/T 20005.9 Carbon and low alloy steels for pressurized water reactor nuclear power plants - Part 9: Seamless steel pipes for class 2 and 3 equipment NB/T 20005.10 Carbon and low alloy steels for pressurized water reactor nuclear power plants - Part 10: Steel pipes for Class 2 and 3 equipment welded with filler metal NB/T 20005.12 Carbon and low alloy steels for pressurized water reactor nuclear power plants - Part 12: Seamless steel pipes for main steam pipelines NB/T 20005.13 Carbon and low alloy steels for pressurized water reactor nuclear power plants - Part 13: Seamless steel pipes for heat transfer tubes of stage 2 and 3 heat exchangers NB/T 20005.14 Carbon and low alloy steels for pressurized water reactor nuclear power plants - Part 14: Grade 2 and 3 butt welded seamless pipe fittings NB/T 20005.15 Carbon and low alloy steels for pressurized water reactor nuclear power plants - Part 15: Grade 2 and 3 pipe fittings welded with filler metal 3 Terms and definitions The terms and definitions defined in GB/T 16702.1-2025 apply to this document. 4 General provisions 4.1 Boundaries of components and attachments for equipment and piping 4.1.1 Boundaries of components The equipment design specification shall define the boundary limits of components with connecting piping or other components. The boundary of a vessel, tank, pump, valve, etc., shall be no closer than the following: a) For welded connections, the face of the first circumferential joint preparation (the connecting weld shall be considered part of the piping); b) For flanged connections, the first flange face (bolts shall be considered part of the piping); c) For threaded connections, the first threaded joint. 4.1.2 Boundaries between components and attachments 4.1.2.1 Attachments Attachments are elements that contact or are connected to the internal or external surfaces of the pressure-retaining part of a component. Attachments are classified by pressure-retaining function as having or not having a pressure-retaining function, and by structural function as having or not having a structural function. Attachments with a pressure-retaining function include: pressure boundary reinforcements, branch piping, and vessel opening reinforcements. Attachments without a pressure-retaining function include: valve guides, thermowell sleeves and rotating vanes; and items in the load path for component supports, such as vessel saddles, supporting lugs and shear lugs, brackets, pipe clamps, trunnions, skirts, and other items in the load-bearing path. Structural function attachments perform a pressure-retaining function or serve as component load-bearing supports. Non-structural function attachments perform neither a pressure-retaining function nor serve in the component load-bearing path, and include nameplates, insulation supports, positioning blocks, and lifting lugs. 4.1.2.2 Jurisdictional boundaries The jurisdictional boundary between the pressure-retaining component and the attachment, as defined in the equipment design specification, shall be no closer to the component's pressure boundary than the limits specified in a) through g) below. Figures 1 through 3 detail the boundaries and construction requirements of this document. a) Attachments integrally cast or forged with the component, and weld overlay on the component surface shall be considered part of the component. b) Attachments with a pressure-retaining function, their welds, and fasteners shall be considered part of the component. c) Except as specified in d) and e) below, the boundary between a pressure-retaining component and an attachment without a pressure-retaining function shall be the surface of the component. d) If the first weld of a non-pressure-retaining structural attachment to the component is located within 2t of the component's pressure-retaining part (where t is the nominal thickness of the pressure-retaining material), that weld shall be considered part of the component. If the aforementioned weld is located beyond 2t of the component's pressure-retaining part, that weld shall be considered part of the attachment. e) The first connecting weld of a welded non-structural attachment to the component shall be considered part of the attachment. The first weld located within 2t of the component's pressure-retaining part shall meet the requirements for welding non-pressure-retaining attachments to pressure-retaining components. f) Mechanical fasteners used to connect non-pressure-retaining attachments to the component shall be considered part of the attachment. g) The boundary may be established at a location farther from the component's pressure-retaining part than defined in a) through f) above, when specified by the design documents.