What must be done to remaining gas piping when gas appliances are disconnected and removed?

When gas appliances are disconnected and removed, it is essential to cap or plug the remaining gas piping. This action is crucial for safety and to prevent any potential leaks of natural gas, which can lead to hazardous situations, including fire or explosion. Capping or plugging the piping ensures a solid and secure closure, effectively sealing the system from any gas release.

Leaving the gas piping open poses a significant danger, as it allows gas to escape into the environment, increasing the risk of accidents or exposure to harmful gas. Cutting off the piping is impractical in many situations, as it can leave the remaining infrastructure vulnerable or create additional challenges in future installations. Adjusting the pressure does not effectively address the physical state of the disconnected piping and is irrelevant to ensuring safety in this context. Therefore, capping or plugging is the most appropriate and responsible course of action when gas appliances are no longer in use.