Metallic pipe joints are permitted to be what?

Metallic pipe joints can be welded or brazed because these methods provide strong, permanent connections that are essential for safely transporting propane and other gases. Welding involves melting and fusing the edges of the metal pipes together, forming a continuous joint that can withstand high pressures and temperatures. This creates a robust seal that minimizes the risk of leaks, which is crucial in handling flammable substances like propane.

Brazing, on the other hand, involves joining two metals together by melting a filler metal that has a lower melting point than that of the workpieces. This method also results in a durable connection and is often used for thinner materials where welding might not be suitable. Both welding and brazing are acceptable within industry standards, particularly in applications that require high integrity and safety.

While other joint types such as flanged, bolted, or screwed joints can also be used in specific contexts, they may not provide the same level of permanence and strength as welded or brazed joints. Flanging can be less rigid, bolted connections may introduce potential for loosening over time, and screwed joints depend on threaded connections which might be vulnerable to leaks if not properly maintained. Thus, for optimal safety and reliability in propane systems, welded or brazed joints are preferred.