Final answer:
Soap and water or water soluble machine oil must indeed not be used for threading PVC and CPVC pipes as they can damage the plastic, leading to potential failures. It's best to use oils specifically designed for PVC and CPVC threading. The correct answer is A. True.
Step-by-step explanation:
The correct answer to whether soap and water or water soluble machine oil must not be used as a cutting lubricant for threading PVC and CPVC piping materials is A) True. These substances are not recommended because they can cause environmental stress cracking in the plastic, leading to potential failure of the piping materials. Instead, manufacturers usually recommend using threading oils specifically designed for use with PVC and CPVC, as they are formulated to be compatible and will not damage the integrity of the pipes.
This is because these materials can be damaged or degraded by certain chemicals, and soap and water or water soluble machine oil may contain these chemicals. Instead, a specific thread cutting oil that is compatible with PVC and CPVC should be used. Therefore, the correct answer is A. True.