Help: Galvanized supply pipe riser to irrigation Back Flow Preventer leak

Discussion in 'Irrigation / Sprinkler Forum' started by monty, Jun 22, 2017.

  1. monty

    monty Member

    Joined:
    May 1, 2006
    Location:
    San Francisco
    We have a fairly new house (built in 2011) with an irrigation back flow prevention setup that has a leak.

    The risers from the buried PVC water supply pipe up to the valve are galvanized steel threaded pipe, and the supply side one now has a pinhole leak. This leak is right at the ground level where the pipe enters/exits the soil. The pipes were wrapped with insulation pipe wrap - but some water got behind the wrap and must have accelerated the corrosion on the pipe.

    Now, I could simply buy a new 18" galvanized pipe nipple and install it to fix my current problem - but it seems that using galvanized pipe isn't the best choice in this area??? Should I look using something else to match the valve material? I am somewhat handy and could do the switch over and so I am curious what is the best option for this setup.

    Thanks for the help in advance!
     
  2. monty

    monty Member

    Joined:
    May 1, 2006
    Location:
    San Francisco
    I thought I would update the thread...

    Without any other advice I decided I should just copy the original setup. I am in the middle of re-doing it at this point. Above is a photo of the failing section - there is a hose clamp and rubber on the leaking area...

    I took it apart last night and there was quite a rust build up inside the galvanized riser pipe. Taking it apart I ended up breaking the PVC threaded end where it met the 90° galvanized elbow - it was too tight to remove, and being under ground level by a foot or so I had no way to brace the joint with an additional wrench. After I broke it I just cut off the broken adapter and capped the 1" PVC line for the night so we had water in the house again!

    Today I am re-building the riser. I have to extend the broken/shortened 1" PVC pipe back to the original length. I am using a new 1" x 18" long galvanized pipe for the riser, a new 1" 90° galvanized female elbow, a new 1" MPT -S Grey PVC Sched 80 fitting to go from the elbow to the PVC water line, and I am also re-using the galvanized coupler.

    Hopefully I can get it all assembled without too much trouble. I also bought some of the pipe wrapping tape, and I will wrap the galvanized pipe and elbow since they will be underground.
     
    Last edited by a moderator: Mar 1, 2020
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  4. Deurgo

    Deurgo New Member

    Joined:
    Mar 15, 2017
    Location:
    Victoria, Australia
    Good morning Monty,

    By chance have you considered using copper pipe for the upright? Resistant to corrosion and simple enough to install. Galvanised pipe has the potential to rust out again (might be 10 years away but still). In Australia most of the lines to and from the meter are all copper straight from the main water supply.

    What you're doing is fine and will work out no problem but just a thought.

    Sorry no one else has been able to offer any insight into your problem.
     
  5. monty

    monty Member

    Joined:
    May 1, 2006
    Location:
    San Francisco
    I did consider copper - but didn't know how well it would work, or if it would improve things. I decided that fixing it for now in galvanized was my best option. Our main domestic water is copper where it comes out of the ground and enters the house. I wasn't sure which copper to use and if it would support the backflow valve...

    I replaced the pipe the other night, and except for picking up the wrong length of PVC pipe and not realizing it was the longer piece until I had glued it all up and it didn't line up. Eventually it went back together OK and seems to be working with no leaks! I am going to fill in the hole this weekend.
     
  6. Gary Swart

    Gary Swart In the Trades

    Joined:
    Sep 1, 2004
    Location:
    Yakima, WA
    PVC sPVChould not be exposed to sunlight. Copper will support most anything better than PVC. Galvanized is strong, but what a hassle cutting and threading. Copper is so much easier to work with.
     
  7. Deurgo

    Deurgo New Member

    Joined:
    Mar 15, 2017
    Location:
    Victoria, Australia
    Hi Monty,

    Glad you got it sorted and everything seems to be running okay by the sound of it.

    http://www.usplastic.com/knowledgebase/article.aspx?contentkey=774 take a look at this, without knowing the exact grade of your PVC pipe I would suggest painting the pipe with an appropriate material to prevent damage from UV. Will last a while but definitely worth considering :)

    Thanks Monty and have a good day.
     
  8. monty

    monty Member

    Joined:
    May 1, 2006
    Location:
    San Francisco
    Sorry I didn't see this last post
    Sorry I just saw this post...Thanks for the reply.

    Fortunately, the PVC pipe is all under the ground a good 1 foot or so. The only exposed pipe is the galvanized, which goes below grade that 1 foot or so and connects to that underground PVC pipe...I don't think I will have any problems with UV damage there thankfully.

    I am still concerned with future leaks and I am contemplating taking it back apart and replacing all the galvanized parts with copper. This might help any future issues I have with iron/rust stains in other areas of the yard that use this water - including our pool!
     
  9. WorthFlorida

    WorthFlorida The wife is still training me.

    Joined:
    Oct 28, 2009
    Occupation:
    Retired
    Location:
    Orlando, Florida
    It seems that galvanized pipe may have been used for its strength or ease using threaded fittings. At ground level it gets bumped, tripped over , hit with a shovel, rake or with a weed string trimmer. If you change over to copper and it is exposed to accidental hits, put the copper pipe inside a PVC pipe, perhaps a 2" PVC pipe of about 12 inches in length at ground level to act as a guard.
     
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