GB/T 8-2021Square head bolts—Product grade C (English PDF)

Foreword

This standard is drafted in accordance with the provisions of GB/T 1.1-2020 "Directives for standardization - Part 1: Rules for the structure and drafting of standardizing documents".

This document is one of the national standards for the "Square head bolts" series, in the series the following documents have been issued.

--- GB/T 8 Square head bolts -- Product grade C;

--- GB/T 35 Square head bolts with small head.

This standard replaces GB/T 8-1988 "Square head bolts -- Product grade C". Compared with GB/T 8-1988, except for the structural adjustment and editorial revisions, the main technical content changes are as follows.

a) The reference thread standards are unified as GB/T 193 and GB/T 9146 (see Table 2; see Table 2 of the 1988 edition);

b) "Commodity specification range" is replaced with "Preferred length range" (see Table 1; see Table 1 of the 1988 edition);

c) "The general technical conditions are in accordance with GB/T 16938", the provision is added (see Table 2);

d) The oxidation surface treatment is deleted (see Table 2 of the 1988 edition);

e) "The technical requirements for non-electrolytically applied zinc flake coatings are in accordance with GB/T 5267.2", the provision is added (see Table 2);

f) "If other technical requirements or surface treatment are required, they shall be agreed upon by the supplier and the buyer", the provision is added (see Table 2);

g) "The requirements for surface defects are in accordance with GB/T 5779.1", the provision is added (see Table 2).

1 Scope

This document specifies the types, dimensions, technical conditions, and marking of square head bolts.

This document is applicable to square head bolts with thread specifications of M10~M48 and product grade C.

2 Normative references

The following documents contain the provisions which, through normative reference in this document, constitute the essential provisions of this document. For the dated referenced documents, only the versions with the indicated dates are applicable to this document; for the undated referenced documents, only the latest version (including all the amendments) is applicable to this document.

GB/T 2 Fasteners -- Ends of parts with external thread

GB/T 90.1 Fasteners -- Acceptance inspection

GB/T 90.2 Fasteners -- Marking and packaging

GB/T 193 General purpose metric screw threads -- General plan

GB/T 1237 Designation system for fasteners

GB/T 3098.1 Mechanical properties of fasteners -- Bolts, screws and studs

GB/T 3103.1 Tolerances for fasteners -- Bolts, screws, studs and nuts

GB/T 5267.1 Fasteners -- Electroplated coatings

GB/T 5267.2 Fasteners -- Non-electrolytically applied zinc flake coatings

GB/T 5276 Fasteners -- Bolts, screws, studs and nuts -- Symbols and descriptions of dimensions

GB/T 5779.1 Fasteners -- Surface discontinuities -- Bolts, screws and studs for general requirements

GB/T 9146 General purpose metric screw threads -- Limits of sizes for the screw […]