Flange is a disc-shaped part, which is most common in pipeline engineering. Flanges are used in pairs and with matching flanges on valves. In pipeline engineering, flanges are mainly used for the connection of pipelines. For the pipes to be connected, various devices are provided with a flange.

Comparison between stainless steel flange and carbon steel flange:

1. Low thermal conductivity, about 1 / 3 of carbon steel. In order to prevent eye to eye corrosion due to flange cover heating, the welding current should not be too large, which is about 20% less than carbon steel welding rod, the arc should not be too long, and the interlayer should be cooled quickly, and narrow welding pass is appropriate.

2. High electronegativity, about 5 times that of carbon steel.

3. Large linear expansion coefficient, 40% larger than carbon steel, and with the increase of temperature, the value of linear expansion coefficient also improves correspondingly.

The welding rod shall be kept dry during application. The titanium calcium type shall be dried at 150 ℃ for 1 hour, and the low-a hydrogen type shall be dried at 200-250 ℃ for 1 hour (repeated drying is not allowed, otherwise the coating is easy to crack and peel), so as to prevent the coating of the welding rod from sticking with oil and other dirt, so as to avoid increasing the carbon content of the weld and affecting the quality of the weldment. When flange pipe fittings are welded, carbides are separated out by repeated heating, which reduces corrosion resistance and mechanical properties. Chrome flange pipe fittings have larger post weld hardenability than American Standard flanges, which is easy to crack. If the same type of chromium stainless steel electrode (gg207) is selected for welding.