Bolt flange design method

Bolt flange connection is a common component in pressure vessels and pipelines.Its rational design not only ensures the long-term safe use of equipment and pipelines,but also avoids material leakage, reduces losses,avoids environmental pollution, prevents major accidents,and avoids casualties. Since many accidents are caused by leaking flange connections, their rational design and related technical requirements have been paid more and more attention.

The traditional bolt flange design method is based on TaylorForg. Method: ASME Code VIII-1 is based on this method. ASME specification VIII-1 has basically not changed much since 1940. This method is the most commonly used method in many international pressure vessel design codes, including the use of gasket coefficients for flange strength calculations. The flange designed according to this method has been widely used in the pressure vessel and pipeline industry. As long as the design is reasonable, this method can meet the requirements of most applications. Some standard flanges, such as EN1092 and ASME B16.5,are developed according to the above method.Therefore,the use of standard flanges can eliminate detailed bolt flange strength calculations.

After the flange is stressed, it will rotate and deform,which is often a main reason for the leakage of the flange connection seal.Therefore,the calculation of the stiffness coefficient was introduced in the later ASME code to control the corner deformation,but this method has not been generally adopted by other pressure vessel codes,such as PD5500.

ANSI ASME B16.36 orifice flange

The three main components of bolted flange connection are flange, bolt and gasket, which play different roles. The flange should have sufficient rigidity, so the design of the flange is actually rigidity design. Although only the stress of the flange is checked, in fact, the purpose of limiting the deformation of the corner is achieved by limiting the stress. But this is still not enough, so the ASME code has added requirements for stiffness calculation. The bolt is mainly a strength design. The bolt must have sufficient strength to bear the internal pressure load and the gasket load. It is very important to control the load of the bolt. Because the preload load of the bolt is difficult to control, and there is stress concentration at the root of the thread, the allowable stress safety factor of the bolt is higher than that of other compression parts.

insulating flanges

Gasket is an important part to ensure sealing. In addition to meeting the requirements of operating conditions, such as the material of the gasket does not chemically react with the medium, the material of the gasket is suitable for the required operating temperature, etc., the gasket should also have The softness and softness have the characteristics of rigidity, which makes it not only strong enough to be crushed, but also enough to rebound.

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