AWS Certified Welding Inspector — FundamentalsWelding SymbolsHard
A CWI is reviewing a blueprint for a joint requiring a backing strip that must be removed after welding. Which of the following supplementary symbols would be used to specifically indicate the removal of the backing strip?
- AA semicircle on the other side of the reference line.
- BThe letters 'R' placed within the backing symbol itself.
- CThe letters 'R' in a circle placed in the tail.
- DA square symbol on the other side of the reference line.
Show answer & explanationAnswer & explanation
Correct answer: B. The letters 'R' placed within the backing symbol itself.
To indicate that a backing strip must be removed after welding, the letter 'R' is placed within the backing symbol (a rectangle or specific backing symbol) on the welding blueprint.
Why the other options are wrong
- A. A semicircle is the melt-through symbol.
- C. Letters in the tail provide general process or WPS information, not specific removal instructions for a backing strip.
- D. A plain square symbol typically indicates a consumable insert or a permanent backing, not necessarily removal.
Removable Backing Symbol
To indicate that a backing strip must be removed after welding, the letter 'R' is placed within the standard backing symbol on the welding drawing.
- Backing symbol is usually a rectangle.
- 'R' inside means remove.
- Ensures no permanent backing material.
Memory trick: The 'R' inside the 'brick' means 'remove' the backing.