Troubleshooting FC Leaks and Connections
The end cap connections are conical NPT (National Pipe Thread), which is an American standard that might not be familiar to users in other countries. Because the threads are conical, over tightening the NPT connections causes the thermoplastic end caps to crack in-service and cause leaks. For this reason, we do not recommend Teflon tape to seal the threads for this reason, as the telflon makes it too easy to over tighten them.
We also recommend to use plastic fittings with FCs – metal fittings can also cause cracking, especially with higher temperature applications. The thermal expansion of common metals used is greater than the plastics used and can also be a source of cracking.