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Old 24-09-2010, 12:51   #1
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Coating Stanless Water Tank

I was wondering if there is a product that is intended for coating the inside of my stainless drinking water tanks, would of course have to have no negative impact on the water quality. The idea being to protect the stainless and extend the service life of the tanks.

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Old 24-09-2010, 13:05   #2
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I thought S/S tanks failed at the welded seems due to slight movements rather than corrosion by freshwater. Can't think of anything I would want on the inside of a tank I would then drink out of. Are they cleaned and bleached regularly? do they look okay on the inside? if so I wouldn't worry.


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Old 24-09-2010, 13:28   #3
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Any coating would increase the risk of crevice corosion unless it is completly watertight. As not much sticks well to SS and most products are more toxic to humans than bare SS I think "au naturale" is the best option.
The grade of SS and the welding are important, however, for long life.
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Old 24-09-2010, 13:30   #4
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SS is the real deal. Thats why doctors knife your pussy bits with stainless steel scalples. You tanks can't be better if they are SS.
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Old 05-10-2010, 09:43   #5
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I don't know about coatings for your stainless, but I suspect no. They fracture at welds from shifting, and in respect to your Westsail tanks, from a lower-grade weld bead and the resultant galvanic corrosion. Also, bleach added to water tanks to prevent algae buildup will cause will cause localized, pin-hole corrosion in your stainless tanks, especially on the underside. Often Westsail set the tanks in the bilge without spacers, allowing debris to fill any voids and create an anoxic environment, perfect for ruining your tank.

One thing I DO NOT suggest is trying to put fiberglass on the outside of your stainless tank; the previous owner of our W32 tried this, but it failed due to SS's gassing, and the already present galvanic pinholes. We replaced our tanks with a single plastic tank (supplied by Bud Taplin.)

Our stainless tanks as I was pulling them out - the yellow skin is the previous owner's attempted repair with a layer of epoxy impregnated fiberglass:

The sludge under our tanks due to pockets for debris to fill:

New tank - 39gal:

MarkJ, you're right - stainless is a great metal, but those expensive scalpels would deteriorate pretty quick in a puddle of bilge water, regularly covered in stagnant, Chloride-rich water.

Good luck Chris,
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Old 05-10-2010, 11:14   #6
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I used an Ameron food grade epoxy five or six years ago on the interior of a stainless water tank, mixed with microbubbles to stiffen the epoxy. Prep required wire brushing and acetone wipe-down, but the stuff stuck and continues to stick to all surfaces it was applied to - sides and bottom, not applied to the top.
Water tasted "plastic" for several months; I eliminated the taste with an under-sink charcoal filter.
don't remember the exact product, but Ameron still produces several food-grade coatings approved by the NSF:

NSF Certified Products - Public Water Supply System Components


Note: this was applied to the inside of the tank through inspection ports - a bit of an ordeal. If I coulda reached the would have been MUCH easier...
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Old 05-10-2010, 16:27   #7
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Hey guys thanks for the replies, Aaron thanks for the pics of you old tanks and all very valid points on causes of corrosion. The stainless tanks on our boat are fairly mint and since they are out of the boat want to try to keep them in service fo the forseeable future. One thing I have been told is a significant cause of weld corrosion is the dissimilar alloys used in the welding material vs the tank. I have been considering NSF approved caulk from Thiokol used to protect weld seams.
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