What is the meaning of seamless steel pipe?

Seamless steel pipe is made of steel ingot or solid tube blank by piercing, then hot rolling, cold rolling or cold drawing. There is no joint in the inner wall of the pipe;

The welded steel pipe refers to the steel pipe with a joint on the surface and a secondary welding joint on the inner wall of the pipe, which is welded after the steel strip or steel plate is bent and deformed into a circular, square and other shape.