Undercut accumulation limit in 300 mm length is less than how many millimeters?

• A. 60 mm
• B. 50 mm
• C. 40 mm
• D. 70 mm

Answer: (B)

Undercut is a groove along the weld toe where the base metal didn’t get fully filled by weld metal, creating a notch that can reduce strength. In inspection criteria, the accumulation limit is about how much undercut can be present when you look at a specific length of weld. For a 300 mm segment, you’re allowed to have only a total undercut length that adds up to less than 50 millimeters. So you can have several small undercut spots along that 300 mm length as long as their combined length is under 50 mm.

This keeps the weld cross-section sufficiently intact and minimizes risk of cracking or failure. For example, if you found undercut spots totaling 45 mm in the 300 mm length, that would pass this criterion; totaling 60 or 70 mm would exceed the limit and fail. A 40 mm total is stricter than the standard requires, so the accepted limit is 50 mm.