What difference between welded steel pipe and seamless steel pipe?

How is Seamless steel pipe made.

API 5L and ASTM Seamless steel pipe adopts steel ingot or solid tube as raw material through the perforated tube, then can be formed by hot rolled, cold rolled or cold drawn. Hot rolled seamless steel pipe is formed by billet forging, perforation, rolling, shaping and other processes. For Large diameter pipe, and thick walled seamless pipe usually made in this way. Cold drawn seamless pipe used cold-drawn forming technology. The material strength is relatively low, the appearance and internal control surface is smooth. Small diameter and thin wall seamless pipe usually made in this way. The seamless steel pipes are rolled by carbon structural steel, low alloy structure steel or alloy structure steel and stainless steel. Seamless steel pipes applied in different industries: Line pipe for pipelines, thermal services, mechanical industries, chemicals etc.

How is Welded steel pipe made

API 5L or ASTM welded steel pipe includes LSAW pipe, SSAW pipe, and ERW steel pipe. These pipes are made with steel strip or steel plate. The manufacturing processes first bending the steel plate, then welded into circular, square and other shapes. Welded steel pipe has the characteristics of high production efficiency, low cost and saving material. It has been widely applied to aviation, aerospace, energy, electronics, automobile, light industry and other industries. With strong corrosion resistance in the acidic environment.