My GC used black cast iron gas pipe to connect from the PGE riser to the interior of the house. He wrapped the pipe from the riser, down into the ground, and up 10" above the ground where the pipe comes back above grade in the crawl space. Then in the crawlspace there is another 15LFT or so of exposed black gas pipe which is not wrapped. Is this ok? Do I need to be concerned about corrosion?

The crawl space is not conditioned, has many open vents, and has no vapor barrier (just dirt on the bottom).

Thanks in advance for your help!

  • 2
    I'm not a plumber, so I would defer to any plumbers that comment, but I don't see any issue with this as long as the pipe is properly painted to prevent rust. If you see any areas where the paint has been marred (particularly by the teeth of the pipe wrench used to install it) then I would just hit those with some Rustoleum. If you're really worried about corrosion, you could have your GC replace with galvanized pipe, but even that should be painted I believe. Commented Aug 29, 2018 at 19:53
  • Thanks @NickAnderson - I'll take a look at that Rustoleum. It sounds like an easy solution. Commented Sep 3, 2018 at 17:25

1 Answer 1


Sewer pipe is typically cast iron ( or plastic). Gas pipe should be steel, ( may be called "black iron") many jurisdictions do not permit galvanized steel in gas service. In my opinion , a very misguided concern over corrosion by sulfur. Steel corrosion is often caused by water, especially with salts. If no water sprays in your crawl space you are very unlikely to have corrosion with the gas pipe. Good ventilation should prevent any condensation caused corrosion. In a similar situation , I had some corrosion of the galvanized electric conduit but not the gas pipe.

  • Ah good point - I probably just typed "cast" out of muscle memory. We have no water spraying in the crawl space. Commented Sep 3, 2018 at 17:25

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.