Disclaimer: I don't know how space modules are welded or what forces act on a space module. Welds fail for multiple reasons - heating too fast, cooling too fas

Disclaimer: I don't know how space modules are welded or what forces act on a space module. Welds fail for multiple reasons - heating too fast, cooling too fast, material defects, human error, equipment issues, oxidation. The best human welder will still have some variance in their weld even if they lay a perfect bead. Once a weld begins to fail, under normal conditions (vibration, stress, etc), it will slowly get worse, but that can also mean deformation around the weld or even sometimes shearing right next to your weld. The article doesn't mention that the growth has been linear only that it is increasing. I expect that the leak is increasing over time in a non-linear fashion as force is applied to the weak area and metal continues to separate and/or shear. Still, 3.7 pounds of atmosphere a day is a very slow leak (relatively), a few bike tires a day.