GB/T 70.2-2025 English PDF

Standard ID	USD	BUY PDF	Lead-Days	Standard Title (Description)	Status
GB/T 70.2-2025	359	Add to Cart	4 days	Fasteners - Hexagon socket screws - Part 2: Hexagon socket button head screws with reduced loadability
GB/T 70.2-2015	70	Add to Cart	Auto, < 3 mins	Hexagon socket button head screws	Valid
GB/T 70.2-2008	70	Add to Cart	Auto, < 3 mins	Hexagon socket button head screws	Obsolete
GB/T 70.2-2000	399	Add to Cart	3 days	Hexagon socket button head screws	Obsolete

Basic data

Standard ID: GB/T 70.2-2025 (GB/T70.2-2025)
Description (Translated English): Fasteners - Hexagon socket screws - Part 2: Hexagon socket button head screws with reduced loadability
Sector / Industry: National Standard (Recommended)
Classification of Chinese Standard: J13
Classification of International Standard: 21.060.10
Word Count Estimation: 18,110
Date of Issue: 2025-10-31
Date of Implementation: 2026-02-01
Older Standard (superseded by this standard): GB/T 70.2-2015
Issuing agency(ies): State Administration for Market Regulation and Standardization Administration of China

GB/T 70.2-2025: Fasteners - Hexagon socket screws - Part 2: Hexagon socket button head screws with reduced loadability

---This is a DRAFT version for illustration, not a final translation. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.) will be manually/carefully translated upon your order.
ICS 21.060.10 CCSJ13 National Standards of the People's Republic of China Replaces GB/T 70.2-2015 Fasteners and internal hex screws Part 2.Reduced Load Capacity of Hex Socket Head Screws Fasteners-Hexagonsocketscrews-Part 2.Hexagonsocket Published on 2025-10-31 Implemented on February 1, 2026 State Administration for Market Regulation The State Administration for Standardization issued a statement.

Table of contents

Preface III Introduction V 1.Scope 1 2 Normative References 1 3.Terms and Definitions 2 4.Type and Dimensions 2 5 Technical Requirements 4 6.Signs and Labels 7 Mark 6 References 8

Foreword

This document complies with the provisions of GB/T 1.1-2020 "Standardization Work Guidelines Part 1.Structure and Drafting Rules of Standardization Documents". Drafting. This document is Part 2 of GB/T 70 "Internal Hex Socket Screws" (content gauge). GB/T 70 has published the following parts. ---GB/T 70.1 Socket head cap screws; ---GB/T 70.2 Fasteners - Hex Socket Head Screws - Part 2.Reduced Load Capacity Hex Socket Head Screws; ---GB/T 70.3 Reduced load-bearing capacity countersunk head screws; ---GB/T 70.4 Fasteners - Hex Socket Head Screws - Part 4.Reduced Load Capacity Hex Socket Head Screws with Flat Round Heads and Flanges; ---GB/T 70.5 Internal Hex Socket Gauges; ---GB/T 70.6 Fine thread for internal hexagon socket head cap screws. This document replaces GB/T 70.2-2015 "Internal Hex Socket Head Screws". Compared with GB/T 70.2-2015, the only changes are structural adjustments and editing. Aside from the sexual alterations, the main technical changes are as follows. a) The standard name and scope have been expanded to include hex socket flat head screws due to their head structure (head size and hex socket penetration depth). The description of reduced load-bearing capacity is shown in Chapter 1. b) For some M16 threaded screws, the thread length b is changed to 3d to comply with GB/T 3098.6 for tensile testing. Test requirements (for screws with reduced load-bearing capacity, tensile testing requires b ≥ 3d) (see Table 2, Table 1,.2015 edition); c) An arbitration datum for the outer diameter of the bearing surface was added (see Figure 1). Considering the manufacturing process of the "flat round head", its minimum value was changed to... dw,min=0.92dk,min (see Table 1,.2015 edition); d) Round the emin value to two decimal places (see Table 1,.2015 edition); e) Increased the maximum penetration depth tmax of the internal hexagon (see Table 1); f) The symbol w is changed to wb to define the wall thickness between the bottom of the cylindrical inner hole and the support surface (see Figure 2 and Table 1,.2015 edition Figure 1). (and Table 1); g) The definition of rf has been changed to allow offset between the radius center and the thread axis (see Figure 1,.2015 version). h) The minimum and maximum standard nominal lengths have been changed (see Table 2, Table 1,.2015 edition); i) The stainless steel A3 and A5 groups have been removed (see Table 2,.2015 edition); j) For performance grades 8.8 (M5, M12, and M16), 10.9 (M3, M6, and M10), and 12.9/12.9 (M4 to M8) The minimum specifications for steel screws, and stainless steel screws with performance grades 70 (M3~M10 and M16) and 80 (M5, M12 and M16). The tensile load has been changed to a more precise value (see Table 4, Table 3 in the.2015 edition); k) Added flags and labels (see Chapter 6). This document is modified to adopt ISO 7380-1.2022 "Fasteners - Reduced load-bearing capacity - Flat head screws - Part 1.Internal hexagonal flat head screws". Screws. The technical differences between this document and ISO 7380-1.2022, and the reasons therefor, are as follows. ---The following has been removed from ISO 7380-1.2022."For additional technical requirements, the stainless steel group can be selected from ISO 3506-1, and..." Dimensions are selected according to ISO 888 or ISO 4753.(Chapter 1), which is not part of the content specified in this document; ---ISO 225 has been replaced with the normatively referenced GB/T 5276 to adapt to my country's technical requirements (see Chapter 4); ---ISO 4753 has been replaced with the normatively referenced GB/T 2 to adapt to my country's technical conditions (see Figure 1); ---ISO 888 has been replaced with the normatively referenced GB/T 3106 to adapt to my country's technical conditions (see Table 2); ---ISO 8992 has been replaced with the normatively referenced GB/T 16938 to adapt to my country's technical conditions (see Table 4); ---ISO 965-1 has been replaced with the normatively referenced GB/T 197 to adapt to my country's technical conditions (see Table 4); ---ISO 898-1 has been replaced with the normatively referenced GB/T 3098.1 to adapt to my country's technical conditions (see Table 4, Chapter 6). Chapter 7); ---ISO 3506-1 has been replaced with the normatively referenced GB/T 3098.6 to adapt to my country's technical conditions (see Table 4, Chapter 6). Chapter 7); ---ISO 4759-1 has been replaced with the normatively referenced GB/T 3103.1 to adapt to my country's technical requirements (see Table 4); ---ISO 4042 has been replaced with the normatively referenced GB/T 5267.1 to adapt to my country's technical requirements (see Table 4); ---ISO 10683 has been replaced with the normatively referenced GB/T 5267.2 to adapt to my country's technical conditions (see Table 4); ---ISO 6157-1 has been replaced with the normatively referenced GB/T 5779.1 to adapt to my country's technical requirements (see Table 4); ---ISO 6157-3 has been replaced with the normatively referenced GB/T 5779.3 to adapt to my country's technical conditions (see Table 4); ---ISO 3269 has been replaced with the normatively referenced GB/T 90.1 to adapt to my country's technical requirements (see Table 4); ---ISO 1891-4 has been replaced with the normatively referenced GB/T 3099.4 to adapt to my country's technical requirements (see 6.2); ---ISO 8991 has been replaced with the normatively referenced GB/T 1237 to adapt to my country's technical conditions (see Chapter 7); ---GB/T 90.2 has been added as a reference to comply with my country's basic standards for fasteners (see Table 4); ---Packaging technical requirements have been added (see Table 4) to comply with my country's basic fastener standards; ---The markup example has been changed to a simplified markup example (see Chapter 7) to conform to GB/T 1237. The following editorial changes have been made to this document. ---The standard title has been changed to "Fasteners - Hex Socket Head Screws - Part 2.Reduced Load Capacity Hex Socket Head Screws"; ---Use GB/T 70.5, GB/T 5267.4 and GB /Z 41117 as informative references instead of ISO 23429, ISO 16048 and ISO /T R20491; ---The references have been changed. Please note that some content in this document may involve patents. The issuing organization of this document assumes no responsibility for identifying patents. This document was proposed by the China Machinery Industry Federation. This document is under the jurisdiction of the National Fastener Standardization Technical Committee (SAC/TC85). This document was drafted by. China Machinery Productivity Promotion Center Co., Ltd., Shandong High-Strength Fasteners Co., Ltd., and Geely Automobile Research Institute (Ningxia). Bo) Co., Ltd., Zhejiang Meiri Intelligent Equipment Co., Ltd., Yuhuan Chunhui Vehicle Axle Co., Ltd., Yanqi Lake Basic Manufacturing Technology Research Institute (Beijing) Co., Ltd. This document is subject to interpretation by the National Fastener Standardization Technical Committee. The release history of this document and the document it replaces is as follows. ---First published as GB 70-1958 in 1958, revised for the first time in 1966, revised for the second time in 1976, and revised for the third time in 1985. Revision; GB/T 70.2-2000 was first published in.2000, partially replacing GB 70-1985.It was first revised in.2008, and the latest version was published in.2015. Second revision; ---This is the third revision.

Introduction

Hex socket screws, due to their wrench-tightening mechanism, are irreplaceable in achieving mechanized and automated assembly and extending the service life of screwdrivers. Fastener products. GB/T 70 "Internal Hex Socket Screws" (content specification) aims to standardize the technical requirements and head inspection methods for internal hex socket screw products. The law consists of the following six parts. ---GB/T 70.1 Socket head cap screws. The purpose is to standardize the types, dimensions, technical requirements, and specifications of socket head cap screws. Signatures, labels, and tags. ---GB/T 70.2 Fasteners - Hex Socket Head Screws - Part 2.Reduced Load Capacity Hex Socket Head Screws. The purpose is to... Specifications regarding the type, dimensions, technical requirements, and markings of internal hexagonal flat head screws whose load-bearing capacity is reduced due to their head structure. Tags and labels. ---GB/T 70.3 Reduced Load Capacity of Countersunk Socket Head Screws. The purpose is to regulate the load capacity reduction caused by the head structure. Types, dimensions, technical requirements, markings, labels, and markings for force-reducing countersunk hexagonal screws. ---GB/T 70.4 Fasteners - Hex Socket Head Screws - Part 4.Reduced Load Capacity Hex Socket Head Screws with Flat Round Heads and Flanges. Purpose The standard specifies the type, dimensions, and technical requirements for internal hexagonal head flange screws whose load-bearing capacity is reduced due to their head structure. Seeking, sign, label, and mark. ---GB/T 70.5 Socket Hex Dimensions. The purpose is to standardize the type and dimensions of socket hex dimensional gauges. ---GB/T 70.6 Fine thread for internal hexagon socket head cap screws. The purpose is to standardize the type and size of fine thread internal hexagon socket head cap screws. Size, technical requirements, markings, labels and markings. The reduced load-bearing capacity of the internal hexagonal flat head screws described in this document may result in a smaller shear area at the tightening point compared to the screw itself due to the head structure. The cross-sectional area affected by stress leads to a reduction in strength. The revised standard clarifies the allowable reduction in load-bearing capacity, providing guidance for design selection and product reliability. It provides evidence. Fasteners and internal hex screws Part 2.Reduced Load Capacity of Hex Socket Head Screws

1 Scope

This document specifies the types, dimensions, technical requirements, markings, and labels for internal hexagonal flat head screws whose load-bearing capacity is reduced due to their head structure. Signature and marking. This document applies to coarse threads with thread specifications from M3 to M16 and performance grades of 8.8, 10.9, 12.9/12.9, A2-70, and A4-70. A4-80, Grade A, reduced load-bearing capacity, steel and stainless steel internal hexagonal flat head screws (hereinafter referred to as "screws"). Note. The minimum tensile load that reduces load-bearing capacity (related to the head size and hexagonal insertion depth specified in this document) must be marked (performance grade). (Add a "0" before the heading). For all specifications and all performance levels, the head load capacity is calculated as 80% of the full load capacity (see Table 4).

2 Normative references

The contents of the following documents, through normative references within the text, constitute essential provisions of this document. Dated citations are not included. For references to documents, only the version corresponding to that date applies to this document; for undated references, the latest version (including all amendments) applies. This document. GB/T 2 Ends of externally threaded fasteners (GB/T 2-2016, ISO 4753.2011, MOD) GB/T 90.1 Acceptance inspection of fasteners (GB/T 90.1-2023, ISO 3269.2019, MOD) GB/T 90.2 Fastener marking and packaging GB/T 197 Tolerances for Standard Threads (GB/T 197-2018, ISO 965-1.2013, MOD) GB/T 1237 Fastener Marking Method (GB/T 1237-2000, eqv ISO 8991.1986) GB/T 3098.1 Mechanical properties of fasteners - Bolts, screws and studs (GB/T 3098.1-2010, ISO 898-1.2009) MOD) GB/T 3098.6 Mechanical properties of fasteners - Stainless steel bolts, screws and studs (GB/T 3098.6-2023, ISO 3506-1. 2020, MOD) GB/T 3099.4 Fastener Terminology – Control, Inspection, Delivery, Acceptance and Quality (GB/T 3099.4-2021, ISO 1891-4) 2018, MOD) GB/T 3103.1 Fastener Tolerances - Bolts, Screws, Studs and Nuts (GB/T 3103.1-2002, idtISO 4759-1.2000) GB/T 3106 Nominal length of bolts, screws and studs and thread length of ordinary bolts (GB/T 3106-2016, ISO 888. 2012, MOD) GB/T 5267.1 Electroplating coatings for fasteners (GB/T 5267.1-2023, ISO 4042.2022, MOD) GB/T 5267.2 Non-electrolytic zinc sheet coating for fasteners (GB/T 5267.2-2021, ISO 10683.2018, MOD) GB/T 5276 Fasteners - Bolts, screws, studs and nuts - Dimensioning and marking (GB/T 5276-2015, ISO 225. 2010, MOD) GB/T 5779.1 Surface defects of fasteners - General requirements for bolts, screws and studs (GB/T 5779.1-2000, idt) ISO 6157-1.1988 GB/T 5779.3 Surface defects in fasteners - Special requirements for bolts, screws and studs (GB/T 5779.3-2000, idt) ISO 6157-3.1988 GB/T 16938 General technical conditions for fasteners—bolts, screws, studs and nuts (GB/T 16938-2008, ISO 8992. ......

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