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I've heard that to join threaded gas piping in my house, I should use either pipe dope or teflon tape rated for gas. Regarding the dope, I've been told to dope "all but the last two threads." My confusion, though, is which two are considered the last two?

Do I not put dope on the two threads

  1. closest to the pipe edge or
  2. closest to the pipe center?

i.e., is "last" referring to the threads closer to the edge or center of the pipe?

enter image description here

FreeMan
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theforestecologist
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1 Answers1

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It's been awhile since I worked with gas pipe, but my understanding was that your area marked as (1) are the last 2 threads.

The reason is so there is no ribbon or tape hanging off the threads that can break off and go upstream and clog something.

What I prefer for sealing any gas pipe is Rector Seal

RMDman
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