What type of piping material is limited to vapor service pressures mentioned earlier?

Polyethylene piping is specifically designed for use in vapor service applications and is often limited to certain pressure ratings. It is known for its flexibility and resistance to corrosion, making it an appropriate choice for propane gas systems where gas is transported in its vapor phase. This limitation is crucial for ensuring the safety and integrity of the piping; polyethylene can handle the pressures associated with vapor services effectively, but it is not suitable for liquid propane due to potential risks such as leakage or failure under higher pressures.

In contrast, metallic piping and copper piping can handle higher pressures and are often used for transporting liquid as well as vapor. PVC piping, while used in other applications, is generally not approved for gas service due to its inability to withstand the conditions associated with gas transport and could pose significant safety risks if used in propane systems. Understanding the specific limitations and applications of different materials is essential in ensuring safe installation and compliance with regulatory standards.