Click for Burger Click for Furuno Click for Perko Click for Walker Click for Mulder

Corroded pipe nipple

Discussion in 'Technical Discussion' started by Trak, Jan 14, 2020.

You need to be registered and signed in to view this content.
Page 1 of 3
  1. Trak, Jan 14, 2020
    #1
    Trak

    Trak Member

    Joined:
    Mar 15, 2014
    Messages:
    50
    Location:
    Lighthouse Point, FL
    This pipe nipple went from my raw water AC pump to the AC compressors. It is brass vs. bronze. Is this due to wear or electrolysis? I replaced with bronze.

    I walked into the engine room and my feet got wet from spraying salt water.

    Attached Files:

    Last edited by a moderator: Jan 15, 2020
  2. Pascal, Jan 14, 2020
    #2
    Pascal

    Pascal Senior Member

    Joined:
    Feb 29, 2008
    Messages:
    8,546
    Location:
    Miami, FL
    You need to have a chat with the idiot who installed this... sadly it s a common mistake I ve seen too many time

    bronze male male nipples are VERY DIFFICULT to find. Usually unavailable at west marine and the like. Are you sure you got a bronze nipple?

    Marelon is a better option than brass
  3. Trak, Jan 14, 2020
    #3
    Trak

    Trak Member

    Joined:
    Mar 15, 2014
    Messages:
    50
    Location:
    Lighthouse Point, FL
    Yes it is a bronze nipple. I couldn’t find a 3” so I had to use a close nipple. Luckily I had enough hose to fit.
  4. Capt Ralph, Jan 14, 2020
    #4
    Capt Ralph

    Capt Ralph Senior Member

    Joined:
    Sep 8, 2004
    Messages:
    13,443
    Location:
    Satsuma, FL
    This is NOT a bronze nipple.

    This is an example of a brass fitting. Bronze is preferred.
    It is a hard task to find all correct materials at times when assembling thru hull fittings.
    Sadly, not all correct hardware will be found at discount suppliers without some deep digging.
    Brass or even some red-brass will fail against bronze.
    It's in the noble material scale list..
  5. Trak, Jan 14, 2020
    #5
    Trak

    Trak Member

    Joined:
    Mar 15, 2014
    Messages:
    50
    Location:
    Lighthouse Point, FL
    I am saying I replaced it with bronze. The one shown in the pic is brass.
  6. Capt J, Jan 14, 2020
    #6
    Capt J

    Capt J Senior Member

    Joined:
    Jul 11, 2005
    Messages:
    14,532
    Location:
    Fort Lauderdale
    I had that situation with a dometic copper A/C discharge tree connected to the a/c pump with a red brass nipple. Did not last a year. The way I fixed it was with a bronze pipe thread to hose barb fitting and another bronze pipe thread to hose barb fitting with a very short piece of hose double clamped in between the two hose barbs. Same length but now bronze on both ends. I can find the bronze to hose barb fittings virtually anywhere. I've never seen a bronze nipple to nipple.

    Most likely electrolysis and erosion.
  7. cleanslate, Jan 14, 2020
    #7
    cleanslate

    cleanslate Senior Member

    Joined:
    May 29, 2018
    Messages:
    1,661
    Location:
    Cherry Hill, NJ
    You will never find a bronze pipe nipple like that cause they are not made. They are all brass. There are some bronze close nipples from Groco etc.,that are large for seawater intakes, etc. but no length nipples made in bronze, all brass.
    I do not think the close nipple you just put in is bronze....Good idea what Pascal and Capt J said.
  8. Pascal, Jan 14, 2020
    #8
    Pascal

    Pascal Senior Member

    Joined:
    Feb 29, 2008
    Messages:
    8,546
    Location:
    Miami, FL
    Where did you source the new bronze nipple ?
  9. Capt Ralph, Jan 14, 2020
    #9
    Capt Ralph

    Capt Ralph Senior Member

    Joined:
    Sep 8, 2004
    Messages:
    13,443
    Location:
    Satsuma, FL
    The brass fitting failed from a dissimilar metal issue from all other materials. Galvanic erosion ate it up the softer material.
    I'm not sure now what you are asking.
    ,rc
  10. Capt J, Jan 14, 2020
    #10
    Capt J

    Capt J Senior Member

    Joined:
    Jul 11, 2005
    Messages:
    14,532
    Location:
    Fort Lauderdale
  11. Capt Ralph, Jan 14, 2020
    #11
    Capt Ralph

    Capt Ralph Senior Member

    Joined:
    Sep 8, 2004
    Messages:
    13,443
    Location:
    Satsuma, FL
    Please note the prices of bronze vs brass.

    Next question. What's up with the Teflon tape? All material must make an electrical connection. If insulated with some tapes or sealants, the electrical connection may not be solid and a difference of potential (galvanic erosion) may happen.
  12. Capt J, Jan 14, 2020
    #12
    Capt J

    Capt J Senior Member

    Joined:
    Jul 11, 2005
    Messages:
    14,532
    Location:
    Fort Lauderdale
    I use Teflon tape, I find it's worn through in plenty of area and makes a good bond. It doesn't leak, you don't have to he-man tighten it so that it remains leak free...….IDK......

    I've seen most manufacturers use pipe dope on water connections.
  13. Trak, Jan 14, 2020
    #13
    Trak

    Trak Member

    Joined:
    Mar 15, 2014
    Messages:
    50
    Location:
    Lighthouse Point, FL
    I did buy the Groco bronze close nipple. I did not install the old brass fitting. The new installation also makes metal to metal contact.
  14. Beau, Jan 14, 2020
    #14
    Beau

    Beau Senior Member

    Joined:
    Jan 15, 2010
    Messages:
    2,261
    Location:
    Beaufort, NC
    NEVER use brass on any through hull fitting or line, even at its terminal end. It will sink you sooner or later. Brass is best left for clocks and decorative feature above the water line. Safe alternatives are myriad, but all need to be inspected regularly.

    A quick eye check: Bronze will be reddish, brass will be yellowish. Scrape thru the oxidation.

    Also the use of plumbers tape (my term) should be left to a minimum because it can interfere with your galvanic grounding system, and in some case completely isolate the fitting. I'd check that seacock and any other metals in that distribution line Use compression fittings or a tapered thread
    Last edited: Jan 14, 2020
  15. cnvsback, Jan 15, 2020
    #15
    cnvsback

    cnvsback Member

    Joined:
    Nov 18, 2009
    Messages:
    56
    Location:
    Fort Lauderdale
    Teflon tape does in fact leak, quite often. As of the last ten years the are numerous other pipe sealant options are available in addition to teflon tape. Teflon tape often also acts as an insulator.

    Try Loctite 565

    Engineered for just about any plumbing circuit up to 2'' diameter and under 3,000PSI nominal operating psi, 565 suffices. Including potable water lines not exceeding 180F.
  16. Capt Ralph, Jan 15, 2020
    #16
    Capt Ralph

    Capt Ralph Senior Member

    Joined:
    Sep 8, 2004
    Messages:
    13,443
    Location:
    Satsuma, FL
    That was a lot of tape on one end. Maybe dope on the far end.
  17. rtrafford, Jan 15, 2020
    #17
    rtrafford

    rtrafford Senior Member

    Joined:
    Jul 13, 2019
    Messages:
    1,732
    Location:
    Vero Beach
    Agreed. My technique is to keep the sealant north of the first thread tooth. While I expect the threads amidst the dope to find some contact, I rely on the initial thread to make certain bond. Keep it clean.

    And, yes, always always bronze. Brass will evaporate with the slightest electrolysis.
  18. Oscarvan, Jan 15, 2020
    #18
    Oscarvan

    Oscarvan Senior Member

    Joined:
    Nov 10, 2015
    Messages:
    969
    Location:
    Chesapeake Bay
    Is pipe available? Tapping a thread on it should be easy considering how soft it is.
  19. Marblehead01945, Jan 15, 2020
    #19
    Marblehead01945

    Marblehead01945 Member

    Joined:
    Jul 25, 2008
    Messages:
    104
    Location:
    Marblehead
    I'm dealing with corrosion as well. Nasty stuff. Sourcing this for replacement.

    Attached Files:

  20. Beau, Jan 15, 2020
    #20
    Beau

    Beau Senior Member

    Joined:
    Jan 15, 2010
    Messages:
    2,261
    Location:
    Beaufort, NC
    Interesting. Is that outlet (?) always beneath the water line as it appears. If so, I think it would need to be bonded or otherwise protected with a zinc.
Page 1 of 3