Torque is the force of rotation, i.e. tightening the nut. The rotation force is measured in Newtons per meter - Nm. For flanges that have bolt fasteners, the torque produces an axial load on them. Axial load (axial) is the force that acts on the edge of the filter element. It can lead to deformation of the element or a violation of tightness. When tightening the bolts, a spring effect is observed.
When tightening the nut, the bolt is tensioned, the load on the gasket increases. The axial load is directly dependent on the friction force. If it changes, then there will certainly be a change in the load that the gasket is experiencing. In order for the bolts to be tightened according to all the rules, it is necessary to lubricate them together with nuts and washers. The axial load is affected and is an important priority in the assembly of flanges. The torque here is attached with a special torque wrench. True, there are more accurate methods that affect the tightening torque of the bolts and the final result.
What should be the force at the bolt connection?
The bolt compresses the flanges together. When tightening the bolts, they must be tightened so as to maintain the load on the gasket under temperature and pressure differences in a normal working process and when the system is under pressure.
An auxiliary load acts in a certain way on the connection. Then the bolted joint is able to adapt under any conditions and at the same time remain airtight.
The yield strength of the material from which the bolt is made is the load that allows it to stretch to the maximum allowable length, after which it returns to its original state. Stretching may be beyond the acceptable measure of fluidity. In this case, when the load is removed, the bolt serves as a kind of "return spring".
When the tightening force of the bolts is exceeded, the acceptable value of the yield strength is stretched, which reduces the load. When tightening the bolt, care must be taken so that there is no constriction that will lead to deterioration. The tightening torque of the bolts is a painstaking process, it is necessary to ensure that the total load on the gasket weakens gradually, at a scale of 40-100% of the yield strength. It is also necessary to ensure that the integrity of the gasket and flanges does not change. The voltage that can be applied to the surface of the gasket must never exceed a predetermined value. A suitable choice of bolt is an indispensable condition for the operation of the flange connection.
How to maintain tightness?
Two conditions that must be met:
- The force committed to compress the gasket and hold it in place. The bolt load should be such that the gasket is compressed over the surface of the flange.
- The effort required:
- For hydrostatic loading.
- The gasket is pressed and held motionless so that the pressure does not get in.
- Keep the load on the gasket after the hydrostatic load is removed.