These two words are much confused in their applications. Commercially, there are many kinds of pipes and tubes of many sizes and materials.

The pipe and tube-making processes described in the following paragraphs embody the essential principles of making pipes and tubes of all kinds in which ductile metals are used.

Cast-iron pipes are much used for large water, oil and gas mains. These are products of the foundry and will not be described here.

All pipes and tubes made of wrought iron or mild steel are manufactured by one of two general processes; either by shaping metal strips called "skelp" into cylindrical form and welding the edges together; or by drawing the tubes from solid billets or flat plates. The products of these two processes are classed respectively as welded or seamless.