There two basic ways of making tubes as either wrapping an accurate hole in strip steel or pushing a very strong hole through a steel bar.

The first method begians with coils of steel strip which are fed automatically through a series of forming rolls which gradually curl the flat strip into a tube shape.The edges of the tube are heated by electric induction and pressd together so that they join by welding.Then the tube travels through a seres of rolls which size and straighten it.

The second type of process,where the"strong hole is pushed through a steel bar",has many variation but the products are generally described as seamless tubes.