Which fittings are allowed in concealed locations?

Fittings that are allowed in concealed locations must adhere to safety and code regulations which aim to minimize the risk of leaks and ensure proper operation in areas that are not easily accessible for inspection or maintenance. Elbows, tees, and couplings are frequently used in various gas piping systems and are designed to redirect or connect sections of pipe effectively.

Elbows provide necessary direction changes within the piping system, tees allow for branching off to other pipes, and couplings connect two sections of pipe together. These types of fittings are often built to withstand pressures and are less likely to leak when properly installed, making them suitable for use in areas that are not visible or accessible without significant effort.

In contrast, unions and plugs, while used in various plumbing contexts, may not offer the same levels of reliability when concealed, as accessing unions for maintenance in hidden locations can be difficult. Additionally, plugs are often used as temporary closure methods and are not intended for permanent installations, which further reduces their appropriateness for concealed spaces. Therefore, the choice of elbows, tees, and couplings is well-founded for concealed locations within gas piping systems, aligning with safety standards.