I am looking for an explanation why yellow gas appliance connectors are single-use. What is it that makes them not reusable? Does it wear and reshape sympathetically so that it can't form another joint without gaps and leaks?

  • 3
    What is a "yellow gas appliance connector"? Please revise to add a reference or photo. Color rarely has such a profound meaning as an industry standard.
    – isherwood
    Feb 28 at 19:20
  • 1
    I suspect OP means a flex pipe. Did you see: diy.stackexchange.com/questions/48059/…
    – izzy
    Feb 28 at 19:38
  • sounds like corrugated stainless steel tubing - CSST? Feb 29 at 3:44
  • @FreshCodemonger no but it does look a lot like it. i mean things when you go to Home Depot in the plumbing dept and ask for appliance connectors
    – amphibient
    Mar 1 at 3:38

1 Answer 1


The most likely answer that's not just "liability insurance CYA" [which is certainly a possible answer] would be the use of a metal-to-metal seal where one part is a fully annealed but work-hardenable metal, such as a copper alloy.

That would be soft and easily deformed to make the seal the first time it was used, and the deformation would work-harden it so it would not be as soft and easily deformed the next time, so it might not seal properly.

Such seals are common in ultra-high vacuum work. I do not know if gas connectors (now) use such seals in some manner, as all direct knowledge I have of fuel gas for homes is decades out of date, and was mostly propane anyway.

  • Sounds like the copper sealing washers in engines. While those washers can be reused by heating them up, I suspect a new connector is much cheaper than a house goes boom than maybe a tow charge.
    – crip659
    Feb 28 at 20:37
  • so do you think it is safe forming a seal in some huge percentage like 99.9 and the replacement is a policy of zero risk bias?
    – amphibient
    Feb 28 at 21:40
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    If designed to have an annealed part making the seal, it's probably not a safe bet using a deformed and work hardened part instead. Say there's a tiny groove. The first time you squeeze it, the seal makes a tiny bump to seal that. You take it apart, you put it together, the parts are not lined up in the same exact relationship, now both the bump and the groove are potential leaks, and the harder material is resistant to deforming to eliminate them.
    – Ecnerwal
    Feb 28 at 22:03

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