Not a direct fit. Joining Inline gas shutoff valve to 1/4" NPT needs a 1/4 NPT (MPT) end of the shutoff, taped. Sealing method, the real-world trap, and the exact part to buy.
Updated 05 September 2026.
Connect Inline gas shutoff valve to 1/4" NPT
How to join 1/4" MPT x 1/4" MFL and 1/4-18 NPT, and what stops it leaking.
Not a direct fit. Joining Inline gas shutoff valve to 1/4" NPT needs a 1/4 NPT (MPT) end of the shutoff, taped.
The two ends
- End A
- Inline gas shutoff valve (1/4" MPT x 1/4" MFL)
- End B
- 1/4" NPT (1/4-18 NPT)
- A seals on
- NPT end taped on the thread; MFL end on the flare face
- B seals on
- on the thread flanks with PTFE tape or paste
- Part needed
- 1/4 NPT (MPT) end of the shutoff, taped
The part to buy
A gas shutoff commonly has a 1/4 MPT (NPT) end and a 1/4 MFL flare end, so its NPT side screws into a regulator or manifold NPT port with tape while the flare side stays clean for an FFL swivel. Two opposite sealing rules on one valve.
Tape only the NPT end because it is tapered and seals on the thread; never tape the MFL flare end. Fitting the shutoff the wrong way round, or taping the flare, is the usual reason a fresh shutoff hisses or will not seat.
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Questions and answers
Connect Inline gas shutoff valve to 1/4" NPT?
Not a direct fit. Joining Inline gas shutoff valve to 1/4" NPT needs a 1/4 NPT (MPT) end of the shutoff, taped.