Commonly Used Basic Knowledge Of Fasteners

1. Commonly used fasteners mainly include: wedge anchor(ETA WEDGE ANCHOR), threaded rods, hex bolt, hex nut, flat washer, photovoltaic bracket

2. Labeling of fasteners

M6 refers to the nominal diameter d of the thread (major diameter of the thread)

14 refers to the male thread length L of the thread

Such as: hex head bolt M10*1.25*110

1.25 refers to the pitch of the thread, and the fine thread must be marked. If omitted, it indicates a coarse thread..

GB/T 193-2003

nominal diameter


Coarse fine


1 0.75


.1.25 1 0.75  


1.5 1.25 1 0.75


1.75 1.25 1  


2 1.5 1  


2.5 2 1.5 1


3 2 1.5 1

3. Performance level of fasteners

Bolt performance grades are divided into more than 10 grades such as 3.6, 4.6, 4.8, 5.6, 6.8, 8.8, 9.8, 10.9, 12.9, etc., among which the bolts of grade 8.8 and above are made of low carbon alloy steel or medium carbon steel and have been heat treated (quenching, tempering, etc.) fire), commonly known as high-strength bolts, and the rest are commonly referred to as ordinary bolts. The bolt performance grade label consists of two parts of numbers, which respectively represent the nominal tensile strength value and yield strength ratio of the bolt material. The number before the decimal point represents 1/100 of the overstrength limit of the material, and the number after the decimal point represents 10 times the ratio of the yield limit to the tensile strength limit of the material.

For example: performance level 10.9 high-strength bolts, its meaning is:

1. The nominal tensile strength of the bolt material reaches 1000MPa;

2. The yield ratio of the bolt material is 0.9;

3. The nominal yield strength of the bolt material reaches 1000×0.9=900MPa;

The meaning of bolt performance grade is an international standard. Bolts of the same performance grade have the same performance regardless of the difference in their materials and origins. Only the performance grade can be selected for design.

The performance grade of the nut is divided into 7 grades, from 4 to 12, and the number roughly indicates 1/100 of the minimum stress that the nut can withstand.

The performance grades of bolts and nuts should be used in conjunction, such as grade 8.8 bolts and grade 8 nuts.

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