The minimum backfilled cover above the top of the pipe or its enclosure shall be 36 inches, except that the minimum cover shall be permitted to be reduced to how many inches where there is no potential damage from surface loads or surface conditions?

The correct answer is 18 inches. In the context of medical gas installations, protecting underground pipes is crucial for ensuring their integrity and functionality. While standard practice requires a minimum backfilled cover of 36 inches above the top of the pipe, there are conditions under which this requirement can be adjusted.

When there are no potential damages from surface loads or adverse surface conditions—such as heavy traffic, equipment placement, or unstable ground—the necessary depth of cover can be reduced to 18 inches. This is appropriate because the risk of damage to the pipe, which could compromise the safety and reliability of the gas being transported, is minimized. Thus, the installation can remain compliant while making practical considerations based on the environment surrounding the pipe.

Understanding these specifications is vital for professionals in the field of medical gas installation, as they must ensure that all components meet safety and performance standards while also being practical given site-specific conditions.