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Galv. or Black Pipe?

frankfrank Member Posts: 202
Black pipe is used for gas, steam, and forced hot water heat; galvanized pipe is used for waste water, and domestic water [the latter not so frequently now, but once was the standard]; copper tube is used for domestic water below grade[type K], domestic water above grade [type L], forced hot water heat [type M], and waste water [type DWV]; plastic is used for waste water, pool lines, forced hot water heating [pex], and in some locations for water distribution; brass was used for water distribution, but now it has become costly and copper took it's place in that market. All the above you'd find in a residential application. Commercially you'd see stainless, glass, aluminum for all kinds of processing [milk, soda, etc.] bwdik?ijap


  • MattMatt Member Posts: 1
    Galv. or Black Pipe?

    I recently purchased a 1928 house with a single pipe system. The prior homeowner (a real jack of all trades, master of none) has mixed both galvanized and black pipe on the system. I am wondering which material is the correct one to use or does it not matter. Please help.
  • ed wallaceed wallace Member Posts: 1,613
    black or galvanized pipes

    all the installation manuals i have ever read said black iron never galvy,copper or pvc
  • frankfrank Member Posts: 202
    pipes, pipes, who's got the pipes

  • S EbelsS Ebels Member Posts: 2,322

    Nicely described Frankie! A little history to boot.
  • mtfallsmikeymtfallsmikey Member Posts: 765
    Just the other day

    I was at Ferguson, having a need for some 2" Schedule 80 PVC fittings, warehouse mgr. sez they are no longer going to stock Sch.80 at all. Also remember an inspector years ago who asked me why I didn't use galv. for the incoming gas line from the meter (duh!)
  • DaleDale Member Posts: 1,317
    gal pipe for gas

    My gas utility uses galvanized pipe for the nipple going through the building wall and an elbow or 2. This way we meet the "protected against corrosion" requirement. We have done this for years and no problems as the nat gas here isn't corrosive. On my own piping all outside pipe is galvanized, again no problems. Try having outside gas pipe near an ocean, Atlanta gas light has speced gal. pipe for years, it's fine with code as long as the gas isn't corrosive. Should a flake or 2 occur the drip catches it.
  • Uni RUni R Member Posts: 589
    Galv Pipe

    Galvanized pipe's main purpose was for protecting the pipes from rusting out when being used to move domestic water. Boiler water doesn't need the additional expense because of galvanized pipe because the water isn't highly oxygenated (it's dead water essentially). Furthermore, galvanized pipe can react with glycol if you are using it and leave sludge in the system.

    So cost and glycol are the two big reasons I can think of. If it's there already and you aren't using glycol it may not be a big factor. Maybe someone else knows of another reason not to use galvanized?
  • Joe A.Joe A. Member Posts: 1
    Galvanized or black?

    I am an amateur plumber only. ;-)

    I am one of these guys who have mixed galvanized into my original black pipe steam installation on a 1920s house.

    Why not?

    The original return ran under the foundation and rotted out.

    I replaced it years ago with black pipe, following conventional wisdom, but failed to take into account that the basement sometimes floods and I live near salt water.

    So as time passed, observing rust and flaking on the "new" pipe, I have used galvanized replacements and I see no reason not to do so when the pipes are likely to be subject to corrosion from outside.

    Any experts disagree?


    Joe A.
  • radioconnectionradioconnection Member Posts: 7

    Galvanized mated to a copper fitting will cause electrolysis and eat away the copper.
  • PlumdogPlumdog Member Posts: 873

    I believe the copper will stay and the galvy will be eaten. Always use brass between the two metals. I've seen galvy water lines 80 years old that still could be unscrewed and seemed OK. Other times it rusts out from the inside and can't be worked anymore.
  • EBEBRATT-EdEBEBRATT-Ed Member Posts: 2,371

    Galvanized is ileagal in MA. for gas pipe.

  • ReynzReynz Member Posts: 84

    Is this what happens?? Floyd, this was installed about 2 1/2 years ago. Is it normal?

    I should be careful with the picture. I almost captured in the image the NAME OF THE COMPANY THAT DID THIS!
  • gerry gillgerry gill Member Posts: 2,663
    you won't have a problem either,

    probably the entire state of california pipes the gas in galvanized for the entire i ever saw out there used black for gas..salt air from the ocean would eat it obviously galvy is fine on gas..i understand along time ago there were coating issues that got many jurisdictions to dis-allow it..probably Timmie would know about that.

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  • FloydFloyd Member Posts: 429
    I think.....

    that it looks like that is where your contractor joined a copper male to black iron female. It can be difficult to get the threads to seal completely between the iron and copper.
    When the piping is warm in the winter you will not see any wetnes, but it is still leaking and leaving the corrosion. In the summer when the piping cools it will leak worse and the water actually runs down into the boiler and can cause problems with the control board.... ( I learned the hard way)
    Have that fixed ASAP!!!!! Should fix it for free... but have fun getting that... :-) Pay for it, it will be worth it in the long run...

  • ReynzReynz Member Posts: 84

    Floyd, Is electrolysis occurring also?

    By the way, a rep from the company came out and took a picture of it with his camera phone. Came back in five minutes later and said they would fix it for $400. I told him I wanted it fixed for free. He said the owner would call. Of course, haven't heard anyting from him since (about two weeks ago). But, does that improper connection cause electrolysis corrosion to occurr also???
  • ReynzReynz Member Posts: 84

    So, isn't that three different pipes being connected together without any apparent non-conducting spacers?

    What is out of the top of the ultra? Galvanized? Then to Black Pipe, then to copper? I'm going to push to have him fix it. If not, some instant messages between him and Congressman Foley are going to show up at the Washington Post!
  • frankfrank Member Posts: 202
    Ya gotta use the right stuff...

    ...if ya wanna get it right. My secrete is using pipe dope over 8-10 turns of teflon tape. Anything over 2", hit the female side w/dope also. When ya solder the joint, do it quickly and wipe down w/wet rag. [Actually, every single solder joint is wiped down w/wet rags by everyone in my shop that does a soldering job.] IF ya can solder the joint before catching the tread and tightening it, then do it that way. bwdik?ijap for forty years
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