What should an excavation deeper than 12" be lined with when installing a mechanical appliance?

When installing a mechanical appliance in an excavation that is deeper than 12 inches, it is required to line the trench with a suitable material to prevent potential hazards such as gas leaks, moisture intrusion, or soil collapse. The most appropriate option in this context is copper pan lining.

Copper pans are favored for their durability, resistance to corrosion, and ability to provide a safe and secure environment around gas lines and connections. They create a barrier that can effectively contain any potential leaks, ensuring that gas does not escape into the surrounding area. Furthermore, the thermal properties of copper also make it suitable for protecting against heat, which is crucial in any gas-related installation.

Using a lining like concrete or wooden casing may not provide the same level of gas integrity and safety assurance as a copper pan. Plastic lining, while useful in certain applications, may not have the necessary durability and resistance to environmental factors that copper offers in this specific application. Thus, the choice of copper lining is a fundamental aspect of ensuring both compliance with safety standards and the long-term reliability of the installation.