What type of fittings should not be used where gas piping is concealed?

Unions should not be used where gas piping is concealed because they are designed as a fitting that can be easily disconnected. While unions are convenient for maintenance and repair, they create a potential point for gas leaks if the fitting becomes loose or is not properly installed. Concealed gas piping, which is often located behind walls or within floors, should use fittings that provide a more permanent connection to ensure safety and minimize the risk of leaks.

Elbows, tees, and angles are typically more secure in their applications within concealed spaces, as they offer less risk of unintended disconnections compared to unions. Hence, it is essential to adhere to safety standards by avoiding unions in hidden gas piping installations.