Flange Connection Design

by | Jun 25, 2022 | Industry Knowledge

Flange design refers to the design of flange connection, including three parts: gasket design, bolt (stud) design and flange body design. The most important method of flange design is the famous Waters method, GB150 is adopted this method.

Flange Design

The main points of its design are:

Gasket design

This is the basis of flange connection design. It should be based on the design conditions and the use of media, select the appropriate gasket type, material. Determine the size of the gasket inside diameter, outside diameter, thickness. And then calculate the compression force of the shims in the preloaded state and the operating state.

Bolt / Stud Design

According to the design conditions, the bolt area need meet the gasket pressing force in the state of pre-tightening. And then calculate the operation. The actual bolt area should not be less than the calculated area.
The principle of bolt design is to determine the smaller bolt center circle diameter. The requirements should base on selecting the appropriate size and number of bolts.

Flange Body Design

Flange design has two cases, which are internal pressure and external pressure. Flanges under external pressure can be designed according to the calculation method of flange under internal pressure. But the operating torque of the flange is slightly different.
Narrow contact face flange calculation method has two kinds. And namely according to the pine flange calculation and flange calculation. Arbitrary type flange is usually calculated according to the integral flange. It can be simplified to the calculation of loose flange under certain conditions.
Loose flange calculation is relatively simple, the thickness of the flange can calculate at one time. The design of the integral flange needs to complete by the method of repeated trial calculation assuming the structural dimensions of each part.
For the integral flange, the dimensions of the flange cone neck and the flange ring are base on the equipment structure. Then calculate the moment of flange and the stress. When the stress and the corresponding allowable stress difference is large, should adjust the original flange size. And repeat the above calculation, until the stress is less than their allowable stress and little difference is reasonable design.
The calculation of the wide contact face flange is based on the simplified model of “simply supported beam.”