This is partly true. The decisive factors are the material and the processing quality. The stainless steel selected should be suitable for the intended/specific application, e.g. ambient/water temperature. Inferior stainless steel, e.g. 1.4401/AISI 316, may corrode in warmer waters such as the Pacific or the Mediterranean. Another decisive factor is the weld seam. In case of hand-welded seams, air inclusions can occur, which may then lead to corrosion.