Stainless Steel Water Tanks

[MartinL]

I've been putting off the job of installing water storage tanks for a while now.

I'd been bit concerned about comments on here regarding rusting of welds on stainless steel tanks. Stainless would be my preference but not if the welds are going to fail in a fairly short time.

I went to my local supplier yesterday to look at their stainless tanks. They had some indoors but also had some that were stored outside, exposed to all weathers. I looked at those. The labels were faded and peeling, they were covered in dirt. The saleswoman said they were there because they were expensive & didn't sell here - a small Isaan town.

After a few minutes of wiping the tanks down with a tissue, there was no sign of corrosion. A clean-up & as good as new, I think.

When I asked how long the tanks had been standing there, I was told " ... more than 5 years ... ".

They were Diamond (DMB?) and Cotto tanks. If they've stood outside all that time with no adverse effects, those are the makes I'll seriously consider although maybe not the specific tanks I looked at.

[wayned]

I have two stainless steel tanks that are over 16 years old. There is no sign of rust on any of the joints. The inlet and outlet fittings are PVC, The joints will corrode if the metal has not been properly treated before and after welding. There was a previous post regarding this showing the signs and actual corrosion, but I'm too lazy to search for it through the mountains of BS.

[lopburi3]

We have two Diamond brand tanks (several decades old) and the only rust was on the top entry cover hinge rivets. As not needed has not caused an issue (cover remains in-place over entry hole and can be removed when required - just no longer attached to tank). This may not be an issue for newer models as happened quite quickly so suspect it was use of wrong material or something that was later corrected. Have not had any issues with tanks/seams or plumbing (which is all SS on body). But am using for Bangkok treated water - have seen reports of limited life from some locations. But in any event am sure will be much longer lasting than the previous square meter galvanized steel tanks (which did not last long at all).

[transam]

Think it's luck of the draw on the welding wire/rods they have used. I have seen rusted welds on tanks.

[IMHO]

What Arjen said.

The two things you need to do are:

1) Buy only Mor Or Gor (TIS) tanks - look for this mark:

2) Filter the water as appropriate before it goes into the tank.

[kamalabob2]

I attended the first day of the Buriram Home Show today at Ruangsangthai Builders Merchants. Plenty of fellow expats to speak with, maybe a few booth spokes models and certainly great Pizza from Roma Pizza. No shortage of plastic tanks on promotion and stainless steel tanks on display. The warranty period was clearly marked and all of the Diamond Brand red label tanks, Advanced Brand Red label, and Advanced Tank green label have a 5 year warranty. So in fact does the "budget line" from Diamond brand called DMB. The Advanced Tank brochure and the Diamond Brand brochure shows the properties of each line of water tank and the larger capacity water tanks have thicker walls than the small 1000 liter or 500 liter stainless water tanks in Thailand. Mr. Pichai stated to me that the stainless steel tanks really do last much longer than 5 years, but well water can make trouble for many of the stainless steel tanks. He recommends the Diamond Brand red label as a first choice, Advanced Red label as a 2nd choice for those considering a long term value. The warranty period on the various grades of "plastic" tanks range from 10 years, 15 years, 20 years and 25 years. Most high volume stores in Thailand pay nearly the exact same price for the water tanks, so the prices on the photo should indicate a normal selling price including VAT for any Thailand building merchants. I am taking family to the Wednesday version of the Buriram Home Expo since they are keen to see some of the Netafim crop irrigation and some sort of tractor parts booth. My wife is keen to only shop for water tanks inside a store and not outside in the sun.

[Soutpeel]

SS does normal wise not rust (oxidise). But....

When those tanks are exposed to normal iron (iron what is solved in the water for example) or chlorine ( now idea if that is used in your local water) then it will rust.

The rust (oxidizing) prevention from SS is based on a thin layer from oxide what is closed for oxygen)

There are a lot of examples from failing SS constructions.

In my home country once a complete roof, made from SS above a indoor swimming pool collapsed. Chlorine and SS are a bad combination.

Arjen.

Nearly right, oxygen is required to form the chrome oxide layer which provides the corrosion resistance in stainless steel, in the case if free iron contamination. The free iron damages the existing chrome oxide layer, and prevents the reformation of the layer as the oxygen has more if an affinity for the free iron than the chrome, in other words it would rather combine with the free iron and rust, than form the chrome oxide layer, at these sites where this occurs corrosion resistance of the stainless is not much better than carbon steel, add some chlorides into the mix and yes you have problems and could have catastrophic failure of the material

In the case of stainless welds, pickling and passivation is a requirement/good practice to remove any free iron from the surface, ie a nitric acid/hydrofluoric type treatment

For light staining citric acid works quite well, ie lemon juice or even orange juice LOL

Edited October 20, 2014 by Soutpeel