In CWB classifications, which class describes a weld with backing?

In CWB classifications, which class describes a weld with backing?

• A. S class
• B. T class
• C. L class
• D. M class

Answer: (A)

In CWB classifications, the code used for a weld tells you how the weld is backed during the welding process. The designation that describes a weld with backing is the one that indicates you have backing material backing up the weld from the backside. This backing helps support the molten metal, stabilizes the root pass, and can improve penetration and quality, especially for joints that need a secure root layer.

So, the reason this option fits best is that it explicitly signals that backing is present, which is the key detail being asked about in the classification system. The other letters refer to different backing conditions or configurations that do not indicate backing being used, so they don’t match the description of a weld with backing.