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This standard is one of the national standard series of Hexalobular Socket Head Screws that consists of:
— GB/T 2671.1 Hexalobular Socket Cheese (Short) Head Screws;
— GB/T 2671.2 Hexalobular Socket Head Cap Screws;
— GB/T 2672 Hexalobular Socket Pan Head Screws;
— GB/T 2673 Hexalobular Socket Countersunk Head Screws;
— GB/T 2674 Hexalobular Socket Raised Countersunk Head Screws.
This standard is drafted in accordance with the rules given in GB/T 1.1-2009.
This standard replaces GB/T 2672-2004 Hexalobular Socket Pan Head Screws in whole, and the following technical deviations have been made with respect to the GB/T 2672-2004:
— "If specifications other than those listed in this International Standard are required, they can be selected from …… GB/T 3098.6 and GB/T 3103.1" is deleted (see Clause 1 of Edition 2004);
— “For the acceptance of the hexalobular socket and for gauges, see GB/T 6188” is added (see Table 1);
— Specifications for passivation of stainless steel screws are specified in GB/T 5267.4 is added (see Table 2);
This standard has been redrafted and modified adoption of International Standard ISO 14583:2011 Hexalobular Socket Pan Head Screws.
The technical deviations between this standard and ISO 14583:2011, together with their justifications, are given below:
— the provision of ISO 7434:14583: "If specifications other than those listed in this International Standard are required, they can be selected from …… ISO 4759-1" is deleted (see Clause 1), which does not fall within the scope of this standard;
— in normative references, Chinese standards are used in place of international standards (see Clause 2); references to GB/T 2 (see Figure 1), GB/T 90.2 (see Table 2), GB/T 1237 (see 5.1) and GB/T 5267.4 (see Table 2) are added to cater basic standards of fasteners in China;
— "d<3mm: as agreed” is added for property class of steel and non-ferrous metal screws (see Table 2), in order to clarify the provisions of the property grade of small specifications of products;
— the property class of non-ferrous metal screws is added (see Table 2) to cater basic standards of fasteners in China;
— the specifications for passivation of stainless steel screws are specified in GB/T 5267.4 (see Table 2) is added, and the product application scope is extended;
— the specifications for packaging (see Table 2) are added to cater basic standards of fasteners in China;
— designation example is modified to a simplified one (see 5.2) to meet the requirements of GB/T 1237.
This standard was proposed by China Machinery Industry Federation.
This Standard is under the jurisdiction of National Technical Committee 85 on Fasteners of Standardization Administration of China (SAC/TC 85).
The explanation of this standard is in the charge of the SAC/TC 85.
The previous editions of this standard are as follows:
— GB/T 2672-1981, GB/T 2672-1986, GB/T 2672-2004.
Hexalobular Socket Pan Head Screws
1 Scope
This standard specifies the types, dimensions, specifications and designation of hexalobular socket pan head screws.
This standard is applicable to hexalobular socket pan head screws of product grade A and with thread sizes from M2 up to and including M10, with property class 4.8, A2-70, A3-70, CU2 and CU3.
2 Normative References
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 2 Fasteners — Ends of Parts with External Thread (GB/T 2-2016, ISO 4753: 2011, MOD)
GB/T 5267.4 Passivation of Corrosion-resistant Stainless-steel Fasteners (GB/T 5267.4-2009, ISO 16048:2003, IDT)
GB/T 5276 Fasteners — Bolts, Screws, Studs and Nuts — Symbols and Descriptions of Dimensions (GB/T 5276-2015, ISO 225:2010, MOD)
GB/T 5779.1 Fasteners — Surface Discontinuities — Bolts, Screws and Studs for General Requirements (GB/T 5779.1-2000, idt ISO 6157-1:1988)
GB/T 6188 Hexalobular Internal Driving Feature for Bolts and Screws (GB/T 6188-2000, idt ISO 10664:1999)
GB/T 9145 General Purpose Metric Screw Threads — Limits of Sizes for the Screw Threads of Medium Quality and Preferable Plan (GB/T 9145-2003, ISO 965-2:1998, MOD)
GB/T 16938 Fasteners — General Requirements for Bolts, Screws, Studs and Nuts (GB/T 16938-2008, ISO 8992:2005, IDT)
3 Types and Dimensions
For types and dimensions of screws, see Figure 1and Table 1.
Symbols and descriptions of dimensions are specified in GB/T 5276.
Note: The shank diameter, ds, is approximately equal to the pitch diameter or equal to the major thread diameter.
