How to Produce Seamless Steel Pipe

A tube is a enclosed shape used to perform some structural function. The shape can be round, rectangular,square or whatever can be manufactured for a particular application. Round tubes is different from pipes in the way they are dimensioned. A 1 1/2-inch round tube has a 1 1/2-inch outside diameter. A 1 1/2-inch round pipe has a 1 1/2-inch inside diameter. The reason being that the outside of tubes is important for structures, however, the inside of pipes is used for fluid flow. 

Seamless steel pipe

The production of seamless steel tube typically begins in an electric arc facility. The steel is then cast as an ingot or continuously cast as a bloom. The bloom is then rolled into a billet. The solid billet becomes a tube by being drawn over a piercing tool by two external rollers set at an angle to each other that move the billet. At this point a “rough” tube has been formed. 

The rough tube is put through an elongator, in which three rollers and an internal mandrel shape the tube closer to its final outside diameter and wall thickness. The next step takes place at a reducing plant, where the outside diameter is brought still closer to its final size and the tube is made oval to ultimately improve its final finish. The rotary sizer is the last step in the basic seamless pipe-making process. The rotary sizer restores the tube to a round shape and brings it to its final outside diameter.