Which document specifies tolerances for weld mismatches?

The document that specifies tolerances for weld mismatches is ASME BPVC Section VIII. This section of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code focuses on the design, fabrication, and inspection of pressure vessels. It includes specific provisions related to how welds should be executed, which encompasses tolerances for weld mismatches that may occur during fabrication.

Weld mismatches refer to the dimensional differences that can arise where two pieces are joined together by welding. These mismatches can impact the integrity and performance of the welded joint, and ASME BPVC Section VIII provides guidelines to ensure that these variations remain within certain tolerable limits to maintain safety standards and performance expectations for pressure vessels.

While other sections of the ASME code, such as Section IX, primarily deal with qualifications for welding procedures and welders, and Section VII focuses on the maintenance of nuclear components, it is Section VIII that addresses issues specific to the design and fabrication of vessel welds, making it the authoritative source for weld mismatches. ANSI B31.3, on the other hand, deals with piping systems and does not cover the specific tolerances related to weld mismatches in vessels.