A welded pipe nipple is a short piece of pipe typically with male threads at both ends. It’s used to connect two female-threaded pipes or fittings together. These nipples are usually made by welding a length of pipe to threaded fittings, creating a seamless connection. They come in various lengths and diameters to accommodate different plumbing or piping needs. They’re commonly used in plumbing, oil and gas, and industrial applications for connecting pipes in a straight run or where flexibility is needed.