If the length is not specified, then length is not a factor. Only the depth is mentioned, so in ANY length of undercut, only the portion that exceeds the acceptable depth is rejectable. For example: The undercut can be 12" long and be acceptable if no portion of it is deeper than specified.
By br549
Date 02-20-2008 15:29
B31.3:04 will give you three letter codes under table 341.3.2. Those are A, I, and H, depending service and conditions.
Therefore as far as length is concerned, it's all or nothing. As for depth, it's as specified per service and conditions. For instance if it is 1.5mm or less per 'I', then it can be the entire diameter of the weld as long as it does not exceed that depth. However; if you have a designation of A, there is none allowed period.