What is the maximum size fillet weld allowed along the edge of a 15/16" plate in a lap joint?

The maximum size fillet weld allowed along the edge of a 15/16" plate in a lap joint is determined by AWS D1.1 code provisions. According to the code, the size of a fillet weld should not exceed the thickness of the thinner material being joined or, in the case of plates such as this one, not exceed 3/8" plus the thickness of the material being welded.

In the case of a 15/16" plate, the maximum allowed size of a fillet weld is 7/8". This is because you must account for the fillet weld dimensioning rules specified in the code, which restrict the size for effective performance and ensure that the weld is adequately penetrated and fused between the pieces being joined.

Other options provided, such as 3/4", 1", and 1 1/4", do not meet the maximum size criteria set forth in the code for a lap joint on a plate of this thickness. A 1" fillet weld would exceed the limitations established by the AWS guidelines and could lead to potential issues with weld integrity and strength.