Silver brazing for stainless tank repair?

[oceanbug]

I am amused with replies. Replies takes you to a broad spectrum of answers, which are useless, don’t need, or simply can’t achieve.
How about ask for tips this way…“my problem is” and I can “only do this”. Tig welding, brain surgery, diesel engine factory overhaul is out of the question.
One of the modern adhesives – polyurethanes – have been holding cars, buses, aircraft together for years.
Then comes the next hurdle. Easy to apply, holds well, but can you get it where you are.
I can TIG weld, but to get on board, especially by dinghy, I am happy to use one good product like…Loctite PL.
It is your job now to find your supplier. Amazon, eBay etc.

[WaldPinkler]

Originally Posted by Ramona

I should add that there are several grades of silver solder from about 5% and up. Obviously it gets more expensive as the amount of silver increases. Buy from a plumbers supply shop and get expert advice.

The main hardware store here in Australia has up to 50% silver. I assumed higher was better only because the lower ones don't mention stainless. It's $35 for the 50%. Not much to lose trying.

[WaldPinkler]

Originally Posted by oceanbug

I am amused with replies. Replies takes you to a broad spectrum of answers, which are useless, don’t need, or simply can’t achieve.
How about ask for tips this way…“my problem is” and I can “only do this”. Tig welding, brain surgery, diesel engine factory overhaul is out of the question.
One of the modern adhesives – polyurethanes – have been holding cars, buses, aircraft together for years.
Then comes the next hurdle. Easy to apply, holds well, but can you get it where you are.
I can TIG weld, but to get on board, especially by dinghy, I am happy to use one good product like…Loctite PL.
It is your job now to find your supplier. Amazon, eBay etc.

Of course that's what happens when I ask for advice in real life too. People don't look from my perspective. If I can repair the tank myself then it's a whole lot easy than removing my 3 tanks and somehow transporting them to a metal shop. My 4wd is stuffed and this river is so full of sand that I can't move around with the deep keel towards the industrial area. Plus it's nonstructural and doesn't need to be pretty - the diy realm.

Are you saying you'd go with that loctite rather than silver brazing? I have a packet of JB weld sitting here already I can play with. I just assumed the brazing is a better fill and less likely to peel and allow water in the edge of the repair.

To be honest it's hard to find information that lays out various solutions or nonsolutions. It's a biased manufacturer or some industrial engineering papers on crevice corrosion.

[oceanbug]

Meticulous cleaning and roughing up with a grinder is relatively easy. Rough up the tank and the patch mating surface. JB only holds mechanically in the scratched surface. Polished smooth stainless is no good. Turn the grinder on, then turn it off, and immediately while it is still spinning, make a fast movement with the tool to scoot over the glue area. This leaves an ugly scratched surface, but do not make the metal thinner.
Urethane prep is the same, and a bit more forgiving in its application than 2 component epoxy. It has flexibility, heat resistance, is waterproof, no crevice corrosion. Patch and tank are insulated from one another. After this, if you want to peel off the patch you will not succeed.

[WaldPinkler]

Urethane? JB weld is epoxy. I understand it's a mechanical bond.

I have some 4200 somewhere. Urethane. But that's a broad range of products.

There's problems welding just making a fold that can catch water. I want to avoid those situations with any filler too.

I haven't pulled the fuel tank yet but it's been painted and mounted with wood blocks on top that have flexed and moved. It's rubbed the paint allowing moisture underneath causing rust. It all looks surface rust from my look at it so far.

This glamorous yacht life. Never ending research how to do **** jobs.

[oceanbug]

Originally you were saying it is a water tank. Now it is a fuel tank?
All repairs other than TIG weld is mechanical.
Yes JB Weld is a 2 component epoxy I know.
The following are mechanical bonds: JB, all urethanes, also all solders like.... soft, brazing, silver-solder is mechanical bonding, and welding is not.
For a fuel tank, only TIG welding will do.
Lots of precautions to remove fuel and all vapors. DIY is just about out of the question.
Some urethane suppliers

https://abcadhesives.com.au/products...ion-adhesives/
https://www.hbfuller.com.au/products/adhesives/

All of which is adequate for a water tank.

[C420sailor]

No one is trying to be a dick. We are just trying to propose what we believe are best practices for a proper repair.

If there are extenuating circumstances due to cost, skill, tools, location, etc, provide them and we will work within the boundaries you present.

[Wotname]

Originally Posted by WaldPinkler

The main hardware store here in Australia has up to 50% silver. I assumed higher was better only because the lower ones don't mention stainless. It's $35 for the 50%. Not much to lose trying.

OK, I have used silver solder from 2.5% through to 45% silver. The principle difference is the temperature required. Simply speaking, the higher the silver percentage, the lower the temperature. There are other differences like the ability to flow into close fitting joints, again the higher the silver percentage, the better the ability to flow. Lower percentages are cheaper and usually mechanically stronger. For percentages of 15 and higher, I would use 602 flux.

If the OP wants to use silver solder then I would recommend 45 or higher percentage of silver and 602 flux.

I have never tried anything lower than 15% on SS but I guess they would work if you have enough heat and the right flux (presumably 602).

Soft solder (50/50 tin/lead) is very easy to use on SS and while some use flux like Bakers, I find run of the mill rust dissolvers just as good (i.e. phosphoric acid).

AFAIK, lead based solder is no longer approved on portable water tanks.

[WaldPinkler]

No, I thank you all for your input. Of course I make my own choices but this is the maintenance subforum of bad news

Regarding tanks. I want to pull the fuel tank too. Removed one of the water tanks first because it's much easier and doesn't have 200L of fuel inside.

I was just out there grinding. It's strange that it has rusty drips down the side that have dried but left pitting where's it's dried. It mostly coming from the welded join.

Most of the pits aren't going far. There's some deeper ones that I could repair. But one wall of the tank is pitted on the inside. I have no idea what that is about. I can't see the rest of the tank because of the baffles. It's looking like I should just replace all the tanks. Expensive days.

Maybe I should learn TIG welding....

[Ramona]

Tig welding is fine if your in a shed and the plate is thin. Personally I arc weld SS plate down to about 2mm. In this case I would silver solder a patch over the hole. If it's a fuel tank then make sure it's clean and the surfaces are abraided then use JB Weld to stick a patch over the hole. JB Weld is not effected by Diesel.

[WaldPinkler]

I can repair but for sure I'm kicking the can down the road. I may well do that for now. The pitting is inside on one sheet.