Textbook Problem

What is the first weld bead of a multiple pass weld called?

To determine

The first weld bead of multiple pass weld.

Explanation of Solution

In multi-pass welding, the first weld bead is called root pass. Root pass gives the sufficient strength and penetration to the weld joint. Two types of root pass are open and close. It can be used either by backing ring or backing strip. Root pass is also used for initial cleaning purpose for the large diameter pipes.