Threaded fittings are generally limited to lower pressure classes (commonly Class 3000 and below per ASME B16.11) because the thread engagement introduces stress concentration points. Butt-weld fittings, by contrast, create a continuous weld joint and are preferred for high-pressure, high-temperature, or cyclic-service applications. Specifying the wrong connection type can be a code-compliance issue in regulated industries.

Not necessarily. Antidumping and countervailing duty orders on stainless steel pipe fittings have historically distinguished between threaded and butt-weld product forms, and scope language varies by order and origin. Importers should obtain a scope ruling or review the specific order's product description carefully before assuming coverage or exclusion.