Where should pipe joint compound be applied?

The application of pipe joint compound is most effective when used on male threads, specifically avoiding the last two threads at the end. This practice prevents any potential for the compound to enter the pipe, which could lead to contamination of the gas line. By leaving the last two threads free of compound, you also minimize the risk of leaks by ensuring that there is a tighter seal at the connection point.

Using compound on all threads or only on female threads does not adhere to best practices for gas connections, as it can lead to complications such as debris entering the gas line or making the connection harder to tighten properly. Additionally, applying compound to the male threads only without leaving the last two threads exposed does not provide the necessary precautions to ensure the safety and efficiency of the gas system. Therefore, applying the compound correctly on the male threads while omitting the last two threads is essential for maintaining safety and function.