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 DN200 flange specifications, as per the GB9119-2000 standard, are as follows: the outer diameter is fixed at 615 mm, 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 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, with a length of 100 mm and 8-grade nuts.

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

In special applications:

- In sewage treatment plants, 316L stainless steel bolts with a diameter of ≥24 mm are used.

- For high-temperature pipelines, the thermal expansion coefficient must be taken into account when selecting bolt materials to ensure compatibility.

Carbon steel is commonly used in normal applications, while 16L stainless steel is preferred in corrosion-resistant scenarios, such as in the chemical and marine industries.

Tags: flange