Flange connection design

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Flange design refers to the design of flange connections, and it includes three components: gasket design, bolt (stud) design, and flange body design. The most prominent method for flange design is the well-known Waters method, which is adopted in GB 150. The key design aspects are as follows: (1) Gasket design. This is the foundation of flange connection design; it is necessary to select the appropriate type and material of gasket based on the design conditions and the medium in use, determine the dimensions of the gasket (inner diameter, outer diameter, thickness), and then calculate the compressive force exerted by the gasket under pre-tightened and operating conditions. (2) Bolt/stud design: Select bolts made of appropriate materials based on the design requirements, and calculate the bolt area required to meet the compressive forces under the gasket pre-tightening condition and operating condition. The actual bolt area to be used should be no less than the calculated area. The principle of bolt design is to determine the smallest possible diameter of the bolt’s center circle. The requirements can be met by selecting the appropriate bolt specifications and quantity. (3) Flange body design: Flange design is divided into two cases based on internal pressure and external pressure. Flanges subjected to external pressure can be designed using the same calculation methods as those for flanges subjected to internal pressure, with only a slight difference in the calculation of the operating torque on the flange. There are two methods for calculating narrow-face flanges: calculation based on loose flanges and calculation based on integral flanges. Arbitrary flanges are usually calculated as integral flanges, and under certain conditions they can be simplified to be calculated as loose flanges. The calculation for loose flanges is relatively simple; the thickness of the flange can be determined at once. The design of the overall flange requires the use of repeated calculations based on assumed structural dimensions for each part. For the overall flange, first assume the various dimensions of the flange neck and flange ring based on the structural conditions of the equipment. Then, the torque exerted on the flange and the various stresses generated are calculated. When the various stresses differ significantly from their corresponding allowable stresses, the originally specified flange dimensions should be adjusted, and the above calculations repeated until all stresses are below their respective allowable values and the differences between them are small; this constitutes a reasonable design. The calculation of wide-flange flanges, regardless of their form, is carried out using the simplified model of a \"simply supported beam\".