What is the looper flange, where is the looper flange used and what pipe fittings?

The looper flange is a movable flange, which is generally matched on the water supply and drainage fittings (the most common on the expansion joint). When the manufacturer leaves the factory, there is a flange at both ends of the expansion joint, which is directly connected with the pipeline and equipment in the project by bolts.

How is the flange connected with the pipe and where is the welding position?

There are many kinds of flange. Generally, flat flange, butt welding flange (long neck flange) and looper flange are used. The flat welding flange is used for medium and low pressure. It adopts plug welding and welding on both sides. The welding depth is 2-5mm from the flange sealing surface. The butt welding flange can be directly butt welded, and the looper flange bolt connection does not need to be welded.

http://www.gcflange.com/