Question

Which of the following is true about back-up strip provided at bottom of single-V grooves?

(a) Back-up strips are commonly used when welding is done from both the sides

(b) Back-up strips are commonly used when  root opening is sufficient

(c) It creates a problem of burn-through

(d) It introduces a crevice into the weld geometry

I had been asked this question in quiz.

This is a very interesting question from Types and Properties of Welding in portion Welded Connections of Design of Steel Structures

Answer 1

The correct option is (d) It introduces a crevice into the weld geometry

The best I can explain: Back-up strip is provided at the bottom of single-V/bevel/J or U grooves. It is commonly provided when welding is done from one side or when the root opening is excessive. It introduces a crevice into the weld geometry and prevents the problem of burn-through.