GB/T 821-2018Square set screws with chamfered end (English PDF)

Foreword

This standard is one of the national standards for the "tightening screws" series. The series includes.

---GB/T 71 slotted tapered end set screws;

---GB/T 73 slotted flat end set screws;

---GB/T 74 slotted concave end set screws;

---GB/T 75 slotted long cylindrical end set screws;

---GB/T 77 hex flat end set screws;

---GB/T 78 hexagonal taper end set screws;

---GB/T 79 hexagonal cylindrical end set screws;

---GB/T 80 hex socket end set screws;

---GB/T 83 square head long cylindrical spherical end set screws;

---GB/T 84 square head concave end set screws;

---GB/T 85 square head long cylindrical end set screws;

---GB/T 86 square head short cylindrical cone end set screws;

---GB/T 821 square head flat end set screws.

This standard was drafted in accordance with the rules given in GB/T 1.1-2009.

This standard replaces GB/T 821-1988 "square head flat end set screws". Compared with GB/T 821-1988, the main technical changes are as follows.

--- Increase general technical conditions according to GB/T 16938 (see Table 2);

---The mechanical performance grade of stainless steel was changed to. A1-12H, A2-12H, A2-21H and A4-21H (see Table 2);

--- Add non-ferrous metals CU2, CU3 (see Table 2);

--- For steel screws, remove surface oxidation treatment, increase the technical requirements of untreated and non-electrolytic zinc sheet coating according to GB/T 5267.2 (see Table 2);

--- For stainless steel screws, remove without treatment, increase the simple processing and passivation treatment technical requirements according to GB/T 5267.4 (Table 2);

--- Add "If other technical requirements or surface treatment are required, the supply and demand agreement should be provided" (see Table 2);

--- Adding surface defects to steel screws.

1 Scope

This standard specifies the type size, technical conditions and markings of the square head flat set screws.

This standard is applicable to square head flat set screws with thread size M5~M20 and product grade A.

2 Normative references

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

GB/T 90.1 fastener acceptance inspection

GB/T 90.2 Fastener Marking and Packaging

GB/T 193 Ordinary Thread Diameter and Pitch Series

GB/T 1237 fastener marking method

GB/T 2516 common thread limit deviation

GB/T 3098.3 Fastener mechanical properties set screws

GB/T 3098.16 fastener mechanical properties stainless steel set screws

GB/T 3103.1 Fastener Tolerance Bolts, Screws, Studs and Nuts

GB/T 5267.1 fastener plating

GB/T 5267.2 fastener non-electrolytic zinc sheet coating

GB/T 5267.4 fastener surface treatment corrosion resistant stainless steel passivation treatment

GB/T 5276 fastener bolts, screws, studs and nuts size code and label

GB/T 5779.1 fastener surface defects bolts, screws and studs are generally required

GB/T 9145 Ordinary thread medium precision, preferred series of extreme dimensions

General technical requirements for GB/T 16938 fastener bolts, screws, studs and nuts

3 Type size

The type and dimensions of the screws are shown in Figure 1 and Table 1.

The size code and label should conform to GB/T 5276.