Leaking stainless steel water tank

[XLD]

There’s a slight but persistent leak along a bottom welded edge  on my water tank. I’m wondering if one of these recently advertised, leak stopping brush applied “glues” would be worth trying. 

[Tracy D'arth]

In short, no.

Stainless tanks are almost always made thin and a bit flexible, its why they go 'bong' when filling. Stainless is brittle and prone to cracks.

If you can get access to the seam, you could get a welder in with a TIG gun.

 

Are you sure it is a leak and not condensation?

 

You may get away with scoring the metal with a wire brush, thoroughly drying, and using a fibreglass repair kit. 

Epoxy putty may also save the day, for a while.

 

Now I will sit back and expect all the comments about tanks that were fixed with cow glue 20 years ago and still don't leak.

[MtB]

3 hours ago, XLD said:

There’s a slight but persistent leak along a bottom welded edge  on my water tank. I’m wondering if one of these recently advertised, leak stopping brush applied “glues” would be worth trying. 

 

Got a link?

 

Might work given the water pressure behind the leak is inherently low. 

 

 

 

 

[Peugeot 106]

MAPP torch, correct silver solder and flux? If you have access. Not my area of expertise but worth spending a few minutes on Google. If you can run some solder into the seam where it shouldn’t flex. I had a pinhole leak in a steel pipe and it was fixed (by someone else) like that. Stainless is I think more awkward but not impossible with the correct solder and gravity may well be on your side

please note I am not pretending to be an expert just offering an idea for investigation. I’d probably take a photo round to a fabricating shop and get their opinion

[Bobbybass]

What I did :

 

roughened up the area and cleaned with meths.

A skim.of fibreglass resin....then a patch of ordinary cooking foil worked carefully around edges so as not to rip.

When dry....another skim of resin and larger cooking foil to overlap the first....

Repeated again.....

 

I did this to a petrol tank on a mates vintage bus until he could source another tank.

 

Still there after 19 years 😃 

 

[blackrose]

Not sure about stainless but I fixed a leak in a mild steel skin tank with JB Weld. You'll need to drain the tank, dry the leaking area (blowtorch?) and rough it up before applying the stuff. I think it's basically epoxy glue with very small metal filings but it worked for me.

 

https://www.jbweld.com/product/j-b-weld-twin-tube (that's the US site but it's available on Amazon)

Edited February 16 by blackrose

[Richard T]

Not easy to do =if it doesn't work be prepared for a big bill. Welds failed on our ss tank - I didn't get much change out of £2k for having it replaced with a rigid plastic one. To get the ss one out the sole plate of the cockpit had to be cut out, the tank cut up in situ, new tank(£660 +vat) fitted along with new filler and connections. Sole plate refitted and all repainted. Remember the tax man adds 20% to costs.

[blackrose]

Blimey! The old integral tank is starting to seem like not such a bad proposition after all. A water tank leak is seriously bad news as there's not much you can do to stop the flow leaking into your boat, so you have no water storage and wet bilges. I'd heard of cracked welds on SS tanks before but never realised it was such a common occurrence.

Edited February 17 by blackrose

[nb Innisfree]

Could be corrosion, apparently exclusion of oxygen can cause it on some grades of ss. 

[kiwiSteve]

what about fitting a bladder... cheaper than chasing dry rot from your fresh water leak...

 

[blackrose]

36 minutes ago, kiwiSteve said:

what about fitting a bladder... cheaper than chasing dry rot from your fresh water leak...

 

 

Talking of bladders, I once had a neighbour on a massive 70ft x 13ft barge built in the 1980s I think and used as a recording studio. He was filling up his bladder tanks which extended almost the full length of the bilges. I was out on the pontoon doing something on my boat when suddenly my neighbour's head popped out of his door. He looked white as a sheet as he'd just heard a massive bang underneath the floor. One of his connected bladder tanks had exploded! What a nightmare! 😯😱

[agg221]

Other than replacement, you have two general lines of attack.

 

One is to use something resin/adhesive based, the other is to use something metal-based which wets out to the stainless.

 

The total exposure is very small, so I wouldn't personally be worried about whether what you use is technically food grade or not - you simply won't have enough of it present and if it is going to work it won't leach, because if it is leaching it is dissolving so would be the wrong approach anyway.

 

There is very little pressure and it doesn't have to deal with getting hot, so the biggest challenges with the resin/adhesive approach are that it has to wet the stainless properly to get a good bond, and it has to then not break down over time. Getting a good bond is about surface preparation. You would need to drain the tank and thoroughly dry the area, then clean it, degrease it (acetone/aka nail polish remover is the best) and then abrade the surface - sandpaper is OK but around welds a scotchbrite will get in deeper. Ideally you would want something low viscosity which creeps into the holes first, something like a creeping crack cure, then seal over the outside. I would use a polyurethane ideally, second choice an epoxy, but if it is not vulnerable to being knocked then a hot melt glue gun would do a very good job. Adding layers to form a true patch shouldn't be necessary if it is just weeping, as you are not really needing to resist the pressure.

 

Using metals to seal it will be stronger and definitely permanent. Welding would be ideal - TIG is neatest and is likely to be how it was first made, but it can be done with 1.6mm rods in MMA if that's all that is available. For this, you would ideally want a rod with a cellulose-based coating rather than rutile, as you can drag these along the surface like a pencil which makes it much easier to control when working at an awkward angle. Brazing (aka silver soldering) does work with stainless, but the fluxes to strip the oxide off the stainless (which is the thing that makes it stainless in the first place) are quite nasty, giving off hydrogen fluoride gas, so if it is in a confined space I would be inclined not to do that. For welding, you would again want the tank drained and really dry, ie dry with hot air, as otherwise you risk hydrogen embrittlement and yes, that can happen with austenitic stainless steels as well as ferritic ones, and you would then want it clean and degreased. For brazing you would prepare it as per for adhesive bonding.

 

Hope that helps.

 

Alec

[Alan de Enfield]

16 minutes ago, agg221 said:

Other than replacement, you have two general lines of attack.

 

One is to use something resin/adhesive based, the other is to use something metal-based which wets out to the stainless.

 

The total exposure is very small, so I wouldn't personally be worried about whether what you use is technically food grade or not - you simply won't have enough of it present and if it is going to work it won't leach, because if it is leaching it is dissolving so would be the wrong approach anyway.

 

There is very little pressure and it doesn't have to deal with getting hot, so the biggest challenges with the resin/adhesive approach are that it has to wet the stainless properly to get a good bond, and it has to then not break down over time. Getting a good bond is about surface preparation. You would need to drain the tank and thoroughly dry the area, then clean it, degrease it (acetone/aka nail polish remover is the best) and then abrade the surface - sandpaper is OK but around welds a scotchbrite will get in deeper. Ideally you would want something low viscosity which creeps into the holes first, something like a creeping crack cure, then seal over the outside. I would use a polyurethane ideally, second choice an epoxy, but if it is not vulnerable to being knocked then a hot melt glue gun would do a very good job. Adding layers to form a true patch shouldn't be necessary if it is just weeping, as you are not really needing to resist the pressure.

 

Using metals to seal it will be stronger and definitely permanent. Welding would be ideal - TIG is neatest and is likely to be how it was first made, but it can be done with 1.6mm rods in MMA if that's all that is available. For this, you would ideally want a rod with a cellulose-based coating rather than rutile, as you can drag these along the surface like a pencil which makes it much easier to control when working at an awkward angle. Brazing (aka silver soldering) does work with stainless, but the fluxes to strip the oxide off the stainless (which is the thing that makes it stainless in the first place) are quite nasty, giving off hydrogen fluoride gas, so if it is in a confined space I would be inclined not to do that. For welding, you would again want the tank drained and really dry, ie dry with hot air, as otherwise you risk hydrogen embrittlement and yes, that can happen with austenitic stainless steels as well as ferritic ones, and you would then want it clean and degreased. For brazing you would prepare it as per for adhesive bonding.

 

Hope that helps.

 

Alec

 

 

So, to summarise .......................... "Get a man in"

[Martin Nicholas]

You need to diagnose the cause of the hole. If it is a crack, then a permanent solution might be impossible. If it is bad welding then it can be repaired, best by using a welder.

 

If your tank "bongs" when you fill it, that needs to be stopped by bracing the sides or cracking will occur eventually.

 

Shockingly, welded plastic tanks are cheaper and better.

Edited February 17 by Martin Nicholas
spelling

[Peugeot 106]

1 hour ago, agg221 said:

Other than replacement, you have two general lines of attack.

 

One is to use something resin/adhesive based, the other is to use something metal-based which wets out to the stainless.

 

The total exposure is very small, so I wouldn't personally be worried about whether what you use is technically food grade or not - you simply won't have enough of it present and if it is going to work it won't leach, because if it is leaching it is dissolving so would be the wrong approach anyway.

 

There is very little pressure and it doesn't have to deal with getting hot, so the biggest challenges with the resin/adhesive approach are that it has to wet the stainless properly to get a good bond, and it has to then not break down over time. Getting a good bond is about surface preparation. You would need to drain the tank and thoroughly dry the area, then clean it, degrease it (acetone/aka nail polish remover is the best) and then abrade the surface - sandpaper is OK but around welds a scotchbrite will get in deeper. Ideally you would want something low viscosity which creeps into the holes first, something like a creeping crack cure, then seal over the outside. I would use a polyurethane ideally, second choice an epoxy, but if it is not vulnerable to being knocked then a hot melt glue gun would do a very good job. Adding layers to form a true patch shouldn't be necessary if it is just weeping, as you are not really needing to resist the pressure.

 

Using metals to seal it will be stronger and definitely permanent. Welding would be ideal - TIG is neatest and is likely to be how it was first made, but it can be done with 1.6mm rods in MMA if that's all that is available. For this, you would ideally want a rod with a cellulose-based coating rather than rutile, as you can drag these along the surface like a pencil which makes it much easier to control when working at an awkward angle. Brazing (aka silver soldering) does work with stainless, but the fluxes to strip the oxide off the stainless (which is the thing that makes it stainless in the first place) are quite nasty, giving off hydrogen fluoride gas, so if it is in a confined space I would be inclined not to do that. For welding, you would again want the tank drained and really dry, ie dry with hot air, as otherwise you risk hydrogen embrittlement and yes, that can happen with austenitic stainless steels as well as ferritic ones, and you would then want it clean and degreased. For brazing you would prepare it as per for adhesive bonding.

 

Hope that helps.

 

Alec

I was hoping that if soldering the flux would clean inaccessible crevices and drag the solder in. It’s cleaning the crevices where the damage probably is that I see as the problem. It’s a case of hopefully a tiny piece of filler in a tiny hole solving the problem. I can’t see a large patch of any type of glue being much help as capillary action will always help a leak in any cracks. With my pinhole the welder kept applying more solder but it still leaked. When he stripped it all off and got a tiny bit in the right place it never leaked again. But the flux gassing off could be a big problem as Alec says. I hadn’t considered that but maybe there is a way round it

 

 

i’ve had success with wood cracks with Captain Tolleys Creping Crack Cure. It works with capillary action. It may be worth seeing if they have any advice. The problem with any glue is that it needs meticulous cleaning and abrading. With epoxy and stainless dinghy fittings I have had success by degreasing the surfaces and then sanding them with wet and dry sandpaper using the resin as the lubrication. But you need the correct temperature it would be useless at today’s ambient temperatures. 
 

I think you need to find a decent fabrication welder, show him photos and at the end of the day leave him to choose whatever method he’s happiest with. In my experience some of these welders are pretty ingenious and not as rip off as you would expect. Find one that likes a challenge. Mine had several goes to seal my pinhole 

 

good luck. Lots of people don’t mind living with small leaks but I’m not one of them

[MtB]

37 minutes ago, Martin Nicholas said:

If you tank "bongs' when you fill it, that needs to be stopped by bracing the sides or cracking will occur eventually.

 

 

If the OP's tank 'bongs', this is probably both the cause of the original crack and a probable cause of future failure of any repair. 

 

Definitely fix the bong, if there is one. 

 

 

[Alan de Enfield]

6 minutes ago, Peugeot 106 said:

I think you need to find a decent fabrication welder, show him photos and at the end of the day leave him to choose whatever method he’s happiest with.

 

 

Get a man in !