scsmith
Well Known Member
I keep reading posts by some folks in threads that indicate a serious misconception about pipe threads.
Pipe threads are tapered. When a fitting with a pipe thread is tightened, it will tighten until the thread flanks contact and make a contact seal on the thread flanks of the mating part.
*****BUT****
The peak of each thread has a small radius, and the valley between the threads has a small radius. These are not the same radius, and when the thread flanks contact, the peak of the thread does not contact the valley in the threads of the mating part.
What does that mean?
If you assemble a pipe thread fitting without sealant, and tighten it until the threads contact, you will still have a spiral leak path, following the spiral path of the valley between the threads.
YOU MUST USE PIPE THREAD SEALANT
or the fitting will leak.
Pipe threads are tapered. When a fitting with a pipe thread is tightened, it will tighten until the thread flanks contact and make a contact seal on the thread flanks of the mating part.
*****BUT****
The peak of each thread has a small radius, and the valley between the threads has a small radius. These are not the same radius, and when the thread flanks contact, the peak of the thread does not contact the valley in the threads of the mating part.
What does that mean?
If you assemble a pipe thread fitting without sealant, and tighten it until the threads contact, you will still have a spiral leak path, following the spiral path of the valley between the threads.
YOU MUST USE PIPE THREAD SEALANT
or the fitting will leak.