Standard dimensions of the DN200 flange

The standard dimensions of the DN200 flange are determined in accordance with the GB9119-2000 national standard: the outer diameter is 615 mm. The bolt specifications depend on the pressure rating and can be M20 bolts or 1-1/4 inch bolts, with materials such as carbon steel and stainless steel being available. The key parameters of the standard specifications for the DN200 flange, as specified in GB9119-2000, are as follows: the outer diameter is fixed at 615 mm, and the inner diameter ranges from 462 mm for PN16 to 484 mm for PN25. The center distance between the bolt holes is 565 mm, with a total of 20 holes evenly distributed. The thickness is 30 mm, but it can increase to 35 mm in high-pressure applications. The guidelines for selecting bolts are as follows:

For flat-welded flanges of PN16, 8 M20 full-thread bolts are required. These bolts have a length of 100 mm and are paired with grade 8 nuts.

For butt-welded flanges of Class 150, 12 1-1/4 inch double-ended studs with a diameter of 34.9 mm are used, and the locking torque should be 720 N·m.

In special applications, such as in sewage treatment plants, 316L stainless steel bolts with a diameter of ≥24 mm are required. For high-temperature pipelines, it is necessary to calculate the thermal expansion coefficient to select the appropriate bolt material.

Tags: flange