Difference between flat welding flange and butt welding flange

Butt welding flange is the same pipe diameter and wall thickness at the interface end as the pipe to be welded, just like two pipes. The flat welding flange is a concave platform which is slightly larger than the outer diameter of the pipe at the interface, and the pipe is inserted and welded inside. The welding performance of butt welding is better and the corrosion is less.

Flat welding and butt welding are the welding methods for the connection of flange and pipeline. When welding flat welding flange, only one side welding is needed, and the inner mouth of pipe and flange connection is not required. The welding and installation of butt welding flange requires double side welding of flange. Therefore, flat welding flange is generally used for low and medium pressure pipeline, butt welding flange is used for connection of medium and high pressure pipeline, butt welding flange is generally at least PN2.5MPa, butt welding is used to reduce stress concentration, the general butt welding flange is mostly neck flange, also known as nipple flange. Therefore, the installation cost of butt welding flange, labor cost and auxiliary material cost should be high, because there is one more process.

Weld neck flanges WN flanges A182 Gr F347 RTJ ASME B16.5

Not all butt welding flanges need to be welded both inside and outside. There are no special requirements. Generally, it is only welded outside. If you haven’t seen 1 / 2 “butt welding flange, flat welding is better because the pipe and flange are vertical, and the pipe will not be inclined.

Flat welding is like butt welding, there is a boss, the boss has a groove, and then the pipe is inserted into the welding. Socket welding is no boss, in the flange body directly opened a groove, just like a blind flange above a hole, and then open a groove. The welding performance of flat welding is a little better than that of socket welding. Generally, I use butt welding flange here, which can be used anywhere.

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