General requirements for the use of bolts

The performance grades of bolts used for steel structure connections include more than 10 grades such as 3.6, 4.6, 4.8, 5.6, 6.8, 8.8, 9.8, 10.9, and 12.9. Bolts of grade 8.8 and above are made of low-carbon alloy steel or medium-carbon steel and have undergone heat treatment (quenching and tempering); they are commonly referred to as high-strength bolts, while the rest are known as ordinary bolts. The bolt performance grade designation consists of two digits, which represent the nominal tensile strength value of the bolt material and the yield strength ratio, respectively. For example: A bolt with a performance grade of 4.6 means that 1) the nominal tensile strength of the bolt material is at the 400 MPa level ； 2. The yield-to-tensile strength ratio of the bolt material is 0.6 ； 3. The nominal yield strength of the bolt material is 400×0.6=240 MPa; it is a high-strength bolt of grade 10.9. After heat treatment, the material achieves: 1. A nominal tensile strength of 1000 MPa for the bolt material ； 2. The yield strength ratio of the bolt material is 0.9 ； 3. The nominal yield strength of the bolt material is 1000×0.9=900 MPa. The performance grade of bolts represents a standard used internationally; bolts with the same performance grade have identical properties, regardless of their material or place of origin. In design, only the performance grade needs to be considered. The strength grades of 8.8 grade and 10.9 grade refer to the shear stress resistance levels of bolts being 8.8 GPa and 10.9 GPa respectively. The nominal tensile strength for 8.8 grade is 800 N/mm2, while the nominal yield strength is 640 N/mm2. Generally, bolts have their strength indicated as “X.Y”; where X*100 represents the tensile strength of the bolt, and X*100*(Y/10) represents its yield strength (as per the standard specification: yield strength/tensile strength = Y/10). For example, in the case of a 4.8 grade bolt, its tensile strength is 400 MPa ； The yield strength is: 400*8/10=320MPa. Additionally: Stainless steel bolts are usually designated as A4-70, A2-70, etc.; the meaning of these designations is explained separately. Units of measurement: There are mainly two systems for measuring length in the world today. One is the metric system, whose units include meters (m), centimeters (cm), millimeters (mm), etc.; this system is widely used in Europe, China, Japan, and other Southeast Asian countries. The other is the imperial system, whose main unit is the inch, which is equivalent to the old Chinese unit of chi; this system is more commonly used in the United States, the United Kingdom, and other European and American countries. 1. Metric system: (decimal system) 1 m = 100 cm = 1000 mm. 2. Imperial system: (octal system) 1 inch = 8 inches; 1 inch = 25.4 mm. 3/8 inch × 25.4 = 9.52. 3. For products with a diameter of 1/4 inch or less, their sizes are indicated by numbers such as 4#, 5#, 6#, 7#, 8#, 10#, 12#. Last edited by Lai Lai on 2009-3-4 at 20:37

What is the difference between bolts used in steel structures and foundations, that is, in civil engineering, and bolts used in pressure vessels and pressure pipelines? ? ? :Q: Asked about: handshake

I have also been learning about related topics recently, such as the standards for the civil engineering foundations of equipment, and the HGT 20643 regulations for the design of foundations for chemical equipment – these mainly concern the foundations for pumps and fans, including information on anchor bolts. SH 3030: Design Code for Foundation of Tower-type Equipment in the Petrochemical Industry; SHT 3057: Design Code for Foundations of Floor-mounted Centrifugal Pumps in the Petrochemical Industry. I don’t know if it will work.

Which standard to use? ? ? :Q

Class C bolts and high-strength bolts used in civil engineering: GB5780-86 \"Hex head bolts of Class C\", GB41-86, GB1228-84 \"Types and dimensions of high-strength large hex head bolts for steel structures\", GB1229-84, GB1230-84, GB1231-84. These are old standards; please refer to the latest versions. The anchor bolts are made of Q235B and Q345.

The answer on the 2nd floor is correct; it’s explained in great detail! At the same time, it is necessary to comply with relevant industry standards.