Pipe Swivel Adapters– Technical Details

The NPSM (American (National) Standard Pipe Straight Mechanical) Pipe Swivel was designed to eliminate hose stress from twisting during assembly and reduce the number of different hose fittings required. It is used with NPT and NPTF male pipe threads. But unlike the NPT and NPTF pipe threads, which seal on the threads themselves, the NPSM Pipe Swivel has a 30° seat (flare) down inside of the swivel nut. This swivel nut is permanently attached to the body and mates with a male pipe thread that has a 30° seat (chamfer) machined into the end of it. Thus bringing both 30° seats (flare and chamfer) together for a meta l-to-metal seal. It should be noted that not all NPT and NPTF male pipe threads have this 30° chamfer. It is optional according to SAE standards under J514. The 30° seat is a rather large chamfer machined into the inside diameter of a male pipe thread and should not be confused with a small deburr chamfer.