Threaded pipe may be used up to 4 inches at a pressure no greater than what value?

Threaded pipe may be used up to 4 inches at a pressure no greater than what value?

• A. 1 p.s.i.g.
• B. 1/4 p.s.i.g.
• C. 1/2 p.s.i.g.
• D. 2 p.s.i.g.

Answer: (C)

The key idea is that threaded gas piping is limited to very low pressures when the pipe diameter is small. For threaded pipe up to 4 inches, the maximum pressure allowed is 1/2 psi gauge. This limit exists because threaded joints rely on sealing compounds and the threads themselves, which are more prone to leaks and aren’t as strong at higher pressures. At higher pressures or with larger diameters, piping is typically welded or uses joints designed for greater strength, providing a safer, tighter seal. Gauge pressure (psig) measures pressure relative to atmospheric pressure, so 1/2 psig is a low, residential/low-pressure range appropriate for threaded gas piping.

The key idea is that threaded gas piping is limited to very low pressures when the pipe diameter is small. For threaded pipe up to 4 inches, the maximum pressure allowed is 1/2 psi gauge. This limit exists because threaded joints rely on sealing compounds and the threads themselves, which are more prone to leaks and aren’t as strong at higher pressures. At higher pressures or with larger diameters, piping is typically welded or uses joints designed for greater strength, providing a safer, tighter seal. Gauge pressure (psig) measures pressure relative to atmospheric pressure, so 1/2 psig is a low, residential/low-pressure range appropriate for threaded gas piping.