Except for stiffener-to-web joints, what is the maximum diameter of piping porosity in fillet welds subject to cyclic loading?

The maximum diameter of piping porosity in fillet welds subject to cyclic loading is determined based on the need to ensure structural integrity and performance under repeated stress. Porosity can introduce points of weakness that could ultimately lead to failure, especially in applications involving cyclic loads, which can cause fatigue over time.

In the context of fillet welds, a maximum diameter of 3/32" for porosity is acceptable because it aligns with industry standards that recognize the need for a balance between permissible defects and structural safety. Smaller porosities have a lesser impact on the overall strength and fatigue resistance of the weld. The rationale is that as long as the porosity remains within this limit, the risk of failure during cyclic loading is minimized.

Larger sizes of porosity like 1/8", 3/16", or 1/4" would significantly increase the likelihood of encountering issues under cyclic stresses, as these would present larger stress concentration points. Therefore, adhering to the 3/32" limit helps maintain the weld's integrity, particularly in critical applications where strength and reliability are paramount.