Carbon steel pipes include seamless and welded pipes. Seamless steel pipes are made from a round and robust piece of steel known as a billet. The billet has to be heated first, then stretched and finally pushed or rolled over a frame or form until the pipe is hollow. Welded steel pipes are made from steel plates and steel strips. These strips and plates are made by moving steel loops and coils with a proper thickness gauge to form a leveled material. The flat leveled material is then measured and cut to the desired lengths.