The maximum design operating pressure for indoor piping systems should not exceed what value unless welded?

The maximum design operating pressure for indoor piping systems is set to ensure safety while handling propane gas. The threshold of 5 psi is established as the maximum pressure that can be safely maintained in indoor systems without the necessity of welded joints for added security.

When operating below this pressure limit, standard fittings and materials that are typically used in pipe installations can effectively contain the gas and its pressure without risking leaks or structural failures. Exceeding 5 psi necessitates the use of welded joints because higher pressures can significantly increase the risk of catastrophic failures in systems not designed for such stress, thus requiring more robust construction methods to ensure safety.

By adhering to this guideline, installers can better ensure the integrity of the gas piping systems they are responsible for, minimizing risks associated with gas handling.