While a strong MPT is essential, other factors also play a role in ensuring a durable threaded joint. One of the most important is making sure that the mating threads are clean and free of corrosion – particularly if you are usingapymetal-free CPVC or PVC. Corrosion can lead to thread failure over time. In addition, using the correct fasteners can also make a big difference. While it’s always a good idea to use stainless steel fasteners in watertight applications, they are even more important when it comes to threaded joints. Not only are they stronger, but they won’t corrode as easily as standard fasteners.