Which of the following gas fittings installed in concealed locations is acceptable?

In gas piping installations, all types of fittings, including threaded elbows, tees, and couplings, can be used in concealed locations as long as they meet safety and building code requirements. When installed properly, each of these fittings provides secure connections that ensure the safe transport of gas.

Threaded elbows allow for direction changes in the gas line, tees enable branching off to additional appliances, and couplings are used to join two sections of piping together. They are all designed to create tight seals that prevent leaks, which is paramount in maintaining safety and efficiency in gas systems.

Building codes typically allow these fittings in concealed spaces, provided they are adequately protected from potential damage and meet the required standards for gas fittings. This acceptance helps ensure that installations are reliable and meet the stringent safety regulations expected in HVAC practices.