Piping that can contain liquid LP-gas and be isolated by valving requires hydrostatic relief valves and shall have an operating pressure of ________.

Piping designed to contain liquid LP-gas and that can be isolated by valving indeed requires specific safety measures, particularly the installation of hydrostatic relief valves. This is due to the nature of liquid propane, which can expand significantly when heated. The correct operating pressure of 350 psig is established due to the need to ensure that the piping can safely contain the pressures generated in various scenarios, including temperature fluctuations and potential thermal expansion of the liquid.

When the operating pressure is set at 350 psig, this level is sufficient to maintain the system's integrity while also providing a safety margin. Regulations and safety standards dictate these requirements to prevent pressure build-up that could lead to dangerous situations, such as ruptures or leaks. Thus, the choice of 350 psig reflects both safety protocols and the capability of materials to withstand high pressures associated with liquid propane.