Tube and pipe fittings under 750720 are connectors designed to join, redirect, or terminate tube or pipe runs — couplings, elbows, tees, and sleeves. Flanges may also fall here if they are integral to a fitting assembly, but standalone valves and stopcocks are classified in the chapter covering industrial valves and similar apparatus. The functional role of the article in the piping system is the key classification criterion.

CBP and downstream buyers typically require a mill test certificate (MTC) or material test report (MTR) showing the chemical composition, mechanical properties, and applicable ASTM or ASME standard. For alloy tubes destined for pressure-service applications, third-party inspection certificates may also be required. The MTC is the primary document used to confirm whether the product is unalloyed (750711) or alloy (750712).