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  1. #1
    catmandoo's Avatar
    catmandoo is offline Registered User
    Location : The Earth but normally in the place of the high stream some where in Perthshire
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    Default Sealing leaking Stainless Steel water tank

    Propose to seal over all the weld seams with glass tape and epoxy . Preparation of surface , type of epoxy and setting time and
    what is the best way of ensuring a good bond and seal ?
    tank too big to take out side boat but can access locally

  2. #2
    Join Date
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    Our 40 gallon S/S water tank started leaking about 6 years ago, when it was only 12 years old. I took it out and pressure tested, and water was coming out through pinholes everywhere in the welds.
    Took it to a pal's welding shop, and they went over all the welds again. Still leaked, but in fewer places...... marked these, and took it back again for more welding.
    Finally! No leaks.
    All fine for a couple of years, then started leaking again. It was only locally in way of one corner, so I got some plastic angle bar and stuck it on along the seam with 5200 (American equivalent of Sikaflex). That seemed to do the trick.
    I think in your case using Sikaflex might be better than epoxy and glass tape.
    Then last year it started leaking again, under my repair and elsewhere. And the water that was pumped out was now chocolate brown.
    So said 'sod it', and decided to resort to a 100 litre flexible tank - so far so good, and there is space for another one in the keel under the cabin sole, so will purchase another 100 litre tank soon.
    Here is a useful guide to Barbados - http://doyleguides.com/barbados.html

  3. #3
    TradewindSailor is offline Registered User
    Location : East Coast Australia
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    I afraid my experiences with leaky stainless steel tanks follows closely with Bajansailor's.

    I pulled out my leaky water tank because the joint was leaking. After cleaning the tank and fixing the weld, I pressure tested it to only 4 psi and found about 20 pin holes. I filled these with epoxy and pressure tested again. Once I had counted 80 pin hole leaks I gave up and replaced it with an inflateable pvc tank by Plastimo.

    If I could fit one I would probably go for a welded plastic tank .... but that option wasn't available then.

    When I purchased my catamaran I inherited another leaky stainless steel tank. I didn't bother even trying to save this one. I hired a nibbler from a sheet-metal worker and cut it out. I had pellets of stainless steel all over the place, but it was worth it. I'll probably make an integral epoxy tank this time.

    Good luck with yours.

  4. #4
    vyv_cox's Avatar
    vyv_cox is offline Registered User
    Location : North Wales, sailing Aegean Sea or Menai Strait
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    I pretty much agree with the other posters, you will be lucky to make an effective repair. However answering your questions:
    a. Adhesion to stainless steel is rarely very good, especially a thin wall that flexes. I would abrade with 60 grit paper and get some epoxy on it quite quickly. Best to do it at an air temperature of about 20 C and make sure the tank is at the same temperature.
    b. West is a good general epoxy, use with woven rovings.
    Answers to some technical queries at http://coxengineering.sharepoint.com

  5. #5
    dingdongs is offline Registered User
    Location : st lawrence bay /essex
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    JB WELD.LOOK ON EBAY.6 STICKS FOR 11.99 PLUS 3.00P&P.will fix all leaks in any tank including petrol and diesel tanks.will cure whilst still leaking and under water.fixes a cracked block too if it freezes up.read the write up 4 yourself.every boater should carry this on board for what it costs.each stick is about 3" long.

  6. #6
    john_morris_uk is offline Registered User
    Location : Home near Exeter, work in Hampshire, boat in Plymouth
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    Quote Originally Posted by dingdongs View Post
    JB WELD.LOOK ON EBAY.6 STICKS FOR 11.99 PLUS 3.00P&P.will fix all leaks in any tank including petrol and diesel tanks.will cure whilst still leaking and under water.fixes a cracked block too if it freezes up.read the write up 4 yourself.every boater should carry this on board for what it costs.each stick is about 3" long.
    Thank you for the advert for your product - your post is a bit transparent perhaps?

    The real answer is 'get a new tank'. I have had a couple of leaking tanks and the stainless fabricators that I use all agree that you are wasting your time trying to repair it.

    I got a quote from tech tanks last time, and in the end got a new s/s tank made up at half the price.

    The only other short term remedy that I know is to use sikaflex.
    Wishing things away is not effective.

  7. #7

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    The welders may not want to take on the job because the joint is soldered. If it is, you can pretty much count on not getting a good weld which is why they said to go to a radiator shop. If it's soldered a good silver solder will work for repairs; don't use lead solder.

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