Recreational Vehicle (RV) Technician Practice Test

Which type of connection in propane systems requires sealant?

1. Pipe flanged

2. Pipe threaded

3. Compression fittings

4. Soldered joints

The correct answer is: Pipe threaded

Pipe threaded connections in propane systems require sealant to ensure a secure and leak-proof seal. The threads on the pipe create a mechanical locking mechanism when two threaded components are screwed together. However, these threads can sometimes leave small gaps where gas may escape if not properly sealed. The application of an approved thread sealant, which is often a non-hardening type specifically designed for use with gas systems, helps to fill these gaps and prevents leaks. This is particularly important in propane systems, as even a small leak can pose safety risks. Proper sealant also assists in the easy disassembly of joints for maintenance without damaging the threads. Other connection types, such as pipe flanged connections, typically use gaskets to create a seal, while compression fittings rely on tight mechanical connections without the need for additional sealants. Soldered joints use melted filler metal to create a strong bond, which inherently seals against leaks without the need for sealant.