What is a mechanical test plug used for in plumbing?

A mechanical test plug is designed specifically to expand and block fitting openings, allowing for pressure testing of plumbing systems. This type of plug is used during system pressure tests to ensure that there are no leaks in the joints and fittings before the system is put into operation. By sealing off the fittings, it allows plumbers to check the integrity of the installed piping under various pressure scenarios.

The functionality of a mechanical test plug is critical in ensuring the reliability of plumbing systems, as it prevents water from flowing through while testing, ensuring that any weaknesses or leaks are identified and addressed before the plumbing is fully operational. Its design typically includes an expandable rubber or elastomer component, allowing it to fit snugly within various pipe sizes.

In contrast, connecting pipes relates to joining them together rather than blocking openings. Repairing leaks typically involves different methods or materials altogether, such as patching or replacing sections of pipe. Supporting heavy fixtures pertains to structural considerations that involve brackets or hangers, which is distinctly different from the role of a test plug in a plumbing system.