Control method of flange nut pre-tightening force


We know that: the flange nut connection must be tighten […]

We know that: the flange nut connection must be tightened during assembly, so that the connection piece is subjected to force before the working load. This pre-loading force is called pre-tightening force, that is, the axial force of the flange bolt. The purpose of pre-tensioning is to enhance the reliability and tightness of the connection to prevent gaps or relative slippage between the connected parts after being loaded. Experience has proved that the appropriate selection of a larger pre-tightening force is beneficial to the reliability of the threaded connection and the fatigue strength of the connection.
However, excessive pre-tightening force will cause the coupling to be broken during assembly or accidental overload. Therefore, in order to ensure the pre-tightening force required for the connection without overloading the threaded coupling, it is necessary to reasonably control the pre-tightening force during assembly.
In order to control the pre-tightening force of the flange nut within a reasonable range after assembly.

Flange nut standard parameters

Function or purpose: mostly used in pipe connections or workpieces that need to increase the nut contact surface
Material: A3 low carbon steel 35K high speed steel wire 45# steel 40CR 35Crmoa
Hardness level: Level 4 Level 5 Level 6 Level 8 Level 10 Level 12
Surface treatment: generally divided into two kinds of color zinc plating and white zinc plating, and generally cold electrogalvanizing!
Main specifications: M5, M6, M8, M10, M12, M16, M20 (Flange nuts above M20 and M14 M18 are not commonly used)
Thread specification: refer to national standard nut thread
National standard code: GB6177-2000