Where should unions and swing joints NOT be used in gas piping?

Unions and swing joints are valuable components in gas piping systems, particularly for creating connection points that allow for easy disassembly for maintenance and repairs. However, their placement is critical for safety and functionality.

When it comes to areas where piping is to be concealed, using unions and swing joints is not advisable. This is due to several reasons. First, concealed fittings can lead to difficulties in inspection and maintenance. If a leak or issue arises in a hidden joint, it may not be easily accessible for repairs or monitoring, which could result in hazardous situations. Concealed locations may also lead to challenges in adhering to regulations which often dictate that joints in gas piping be accessible for periodic inspection and maintenance.

In scenarios where visibility and access are possible, using unions and swing joints is generally acceptable, as it promotes safety and ease of maintenance. Additionally, in high-pressure sections, the integrity of the joint becomes crucial, and it is preferable to use welded or threaded connections to minimize the risk of leaks due to the high-stress conditions. Thus, the correct choice emphasizes the importance of maintaining accessibility and safety in the installation of gas piping systems.