Basically a stainless cap are applied, to shut down the end of a pipe. The stainless Cap is available for all pipe dimensions, and is sometimes also used for other purposes. The largely used variation of the stainless cap is the so-called ellipsoidal or dished head. They are used to close pipes of large diameters, and are similar to those used for constructing vessels.
A stainless steel butt weld cap is a type of pipe fitting that covers the end of a pipe. On a weld, if it is a temporary close, or the contractor wants to add to the piping system in the future additional pipee the stainless butt weld cap can be used to close the pipe and can be cut off and the pipe system extended as needed. This way you will not have less pipe than you need and the new fitting can be attached correctly.
The stainless cap has a female butt-weld, beveled opening for welding to male connections with a smooth bore.