When connecting pipes, what must be avoided to ensure accurate pressure testing?

To ensure accurate pressure testing when connecting pipes, it is essential to avoid using valves as bulkheads. Valves are designed to control the flow of gas, and their use in a connection or as a bulkhead can create variables in pressure readings. Using a valve in this way can lead to potential leaks or obstructions, which might cause inaccurate pressure measurements and compromise the integrity of the system being tested.

In pressure testing, it is crucial that connections are made with fittings that provide a reliable seal and do not introduce points of failure. Using valves improperly can also impede proper testing procedures and may lead to safety hazards if there are hidden leaks or incorrect readings due to the presence of a valve instead of a solid connection.

The other options may present challenges or limitations, but they do not directly affect the pressure testing integrity in the same critical way as using valves as bulkheads does. For example, non-metallic pipes may not meet specific pressure ratings, short lengths of pipe can create stress points, and softer materials for sealing might be less durable but are not as impactful on the testing process as improperly utilizing a valve.