Replacing old 275 Gallon Oil Tank because its old

[fire_man]

My indoor basement oil tank is 34 years old. The oil tank replacement companies seem to agree it needs replacement after 30 years because it can rust from the inside out due to water in the tank.

Any knowledgeable opinions on this?

 

[peakbagger]

I am in same shape with a 30 year old tank. I have a second tank that's newer and since I don't burn oil to speak of I am planning to just pump what is left in the newer one and yank the oldest one out. I am also considering putting in 200 gallon Roth Tank as they take up a lot less room and have double containment. The also weigh a lot less. The down side is the burner fuel pump needs to be set up for suction lift. The life of older tanks seem to be variable but since they rot from the inside out unless you have an ultrasonic test rig you will never know. My parents house had a 40 year old one. One day when visiting, my mom mentioned she found a wet spot under it so she put a pan under it. I had them call the oil company the next day and despite it looking fine on the outside once they had it out they could tap all along the bottom and put the hammer through it. I have been told that someone with UT equipment could probably measure the thickness but expect that corrosion cells form so its hit or miss. If it does let loose its nightmare, that sweet heating oil smell says in the house for years as it soaks into the concrete. The big hassle is getting rid of old tanks. They cant be treated as scrap until they are cleaned and that not fun. I haven't done it but have paid contractors to do much larger ones and its goey mess.

 

[fire_man]

Good Info. I heard about the Ultasonic Test but I question how reliable it really is. I'd rather just put the money towards a new tank.

I also heard about double lined tanks. I don't like the idea of changing the burner pumps. I plan to get some estimates to have the job done - there are a bunch of companies in the area that specialize in tank removal/replacement.

 

[jayoldschool]

They are correct. I can just about guarantee that that tank is starting to sweat on the bottom. I just replaced my tank last year. It was installed in 2002, and once I got photos with good light of the bottom, I could easily see rust spots, and weeping on the bottom of the tank. Replaced it with a 30 year fiberglass tank, and happy to have no insurance concerns.

 

[peakbagger]

Good Info. I heard about the Ultasonic Test but I question how reliable it really is. I'd rather just put the money towards a new tank.

I also heard about double lined tanks. I don't like the idea of changing the burner pumps. I plan to get some estimates to have the job done - there are a bunch of companies in the area that specialize in tank removal/replacement.

I dont think you need to change to burner pump, all you have to do is replumb it. I haven't done it so haven't done a lot of research on it.

 

[salecker]

I have a tank from the seventies.No plans of replacing it,they were made to last back then. I have seen a bunch of newer tanks fail.

 

[maple1]

Insurance companies here have a lot to say about this.

One of the reasons I got rid of all our oil stuff was we would have had to put a new tank in in 3 more years - 20 years seemed to be their limit.

They made my parents replace their old one, then made them replace the replacement 6 years later.

 

[fire_man]

They are correct. I can just about guarantee that that tank is starting to sweat on the bottom. I just replaced my tank last year. It was installed in 2002, and once I got photos with good light of the bottom, I could easily see rust spots, and weeping on the bottom of the tank. Replaced it with a 30 year fiberglass tank, and happy to have no insurance concerns.

I have not heard about 30 year figerglass tanks. How big a tank is that?

And less than 20 years on your old steel tank seems terrible.

 

[salecker]

Yea insurance company's suck.
I have seen quite a few people stuck with the cleanup after they replaced their old tanks with new ones,which failed.
There was a run of new tanks up here that failed after about 6 years.Two outside and one inside that i know of,all owners were left hi and dry by their insurance.I know contractor that lost his building under construction to fire with insurance,he almost lost his private home because the insurance company used some weasel words to wiggle out of covering the fire.He carries no insurance on his construction sites or private home anymore.

 

[fire_man]

Yea insurance company's suck.
I have seen quite a few people stuck with the cleanup after they replaced their old tanks with new ones,which failed.
There was a run of new tanks up here that failed after about 6 years.Two outside and one inside that i know of,all owners were left hi and dry by their insurance.

Can you elaborate any on the tanks that failed after 6 years? Were they the plain vanilla 14 gauge standard single wall steel tanks?

Did they fail catostrophically? Hard to imagine it was rust after only 6 years.

 

[Seasoned Oak]

I made a wood stove out of an old oil tank. You could heat a pole barn with that thing. Heck of a heat exchanger all that Sq footage of hot steel .

 

[maple1]

I think when my parents had to replace that 6 year old replacement I mentioned earlier, it had something to do with the way it was stamped, and gauge vs. millimeters. And a rounding issue between the two. I think it was stamped 1.5mm (or 1.6?) which is just a hair thinner than 14 gauge. But the steel wasn't actually made of thinner material - it just was stamped that way with converting then rounding to nearest 0.1mm.

It was all very stupid anyway, but they had to do it.

 

[Fred61]

I've done a post mortem on several oil tanks either by cutting an 18x18 inch opening for inspection by the scrap yard or to make firepits and usually what I see is a moderately rusty area at the lowest point of the tank, within that rusty area I always see deep pits of various sizes where water drops have sat and pretty much "burned" into the steel. What happens is that the water collects sulfur from the oil and turns into a sulfuric acid cocktail.

I personally haven't attempted any preventative measures but I suppose a quart or two of methyl alcohol dumped into the tank every now and then would keep the water in suspension and allow it to flow out with the fuel oil.

 

[fire_man]

I've done a post mortem on several oil tanks either by cutting an 18x18 inch opening for inspection by the scrap yard or to make firepits and usually what I see is a moderately rusty area at the lowest point of the tank, within that rusty area I always see deep pits of various sizes where water drops have sat and pretty much "burned" into the steel. What happens is that the water collects sulfur from the oil and turns into a sulfuric acid cocktail.

I personally haven't attempted any preventative measures but I suppose a quart or two of methyl alcohol dumped into the tank every now and then would keep the water in suspension and allow it to flow out with the fuel oil.

Now this tells me ultrasounding the bottom is pretty much useless. I can't imagine it could detect a small pitted area reliably.

Your forensics is consistent with pictures I have seen of tanks oozing oil out of pin holes at the bottom.

 

[Fred61]

Some pits I've seen aren't so small. Some are about the area of the head of an 8d nail.

 

[jayoldschool]

Here's my new tank. 500l, the old one was 900l.

 

[fire_man]

Do the fiberglass tanks cost a ton more $$? I like the drip pan underneath.

I read the vertical tanks like yours are better reinforced - not sure what that means.

 

[peakbagger]

The pits are corrosion cells. Sort of like cavities, once they start somewhat randomly, they keep growing.

Fuel oil tanks were largely unregulated years ago. Developers only spend money on features that sell and an extra thick oil tank is not going to get someone to buy a house. Therefore mechanical systems are put in as cheap as possible to meet some out of date minimum code which may or may not be enforced. The developer is long gone before durability issues pop up. A vertical tank has to be marginally stronger than horizontal tank as the pressure at the base of it is slightly higher and the design needs to be bit more robust for seismic purposes. Realistically any single wall carbon steel tank is at risk as its going to corrode. I have seen stainless steel versions of standard oil tanks over the years used in corrosive environments but have never found the supplier. IMHO the Roth type vertical polyethylene tanks with secondary galvanized containment is the best set up I have seen. Light weight to move around and they take up half the floor space and its not going to rot. I have less faith with fiberglass tanks as are a lot more prone to manufacturing defects and usually not cost competitive with poly tanks built to the same specification.

 

[fire_man]

Funny I had concern with manuacturing defects in the fiberglass tanks. They seem more complicated to make. But they have really long warranties. Grandby makes Fiberglass with a 30 year warranty.

Granby makes a 20 year steel tank with a polyurethane coating.

I guess the polyurethane is like a double shell?? Seems like it would hide a leak in the steel.

I'm trying to get educated on the Roth units.

I agree carbon steel is subject to corrosion but it seems the best bang for the buck is a super thick carbon steel tank - like 12 gauge. My parent's house had a tank installed in the 50's they removed in the year 2000 that never leaked. Now that tank was built like a tank!

I'm guessing stainless would be prohibitively expensive and I have not seen any residential SS tanks.

 

[peakbagger]

A poly lined tank if its done right should last if its applied correctly. One pinhole or void in the coating and the corrosion will start a corrosion cell and start rotting under the lining. Of course the rot is caused by water that collects in the tank bottom so the pinhole has to be in the tank bottom. Hard to beat a secondary containment with leak detection.

I used to have to specify and supervise spray and brush lining of various chemical tanks and containments. One of the many things things I learned is never apply coatings when the temps are warming up as dissolved gases in the coating will form and expand as the temps warm up. This makes all sort of pinholes in the coating. If the temps are dropping, then the bubbles do not form as often and the ones that do and shrink leading to a much smoother more chemical resistant coating. The other thing was surface prep is everything. Near white metal sandblasting could not be beat, the coating grabs onto the surface texture of the steel and its not coming off, anything less than that is compromise. I am always worried that in a production situation that I might get the tank that was coated just before coffee break. Sure the tank may have some sort of guarantee but expect it doesnt pay a dime towards cleanup which is the big cost

 

[fire_man]

I am finding steel tanks lined inside with Polyurethane and Polyurethane tanks lined inside with steel. What a confusing bunch of choices.

I have not read anything bad about fiberglass tanks.

 

[salecker]

Can you elaborate any on the tanks that failed after 6 years? Were they the plain vanilla 14 gauge standard single wall steel tanks?

Did they fail catostrophically? Hard to imagine it was rust after only 6 years.

Bad welds.Tidy Tanks not sure what gauge and one was a weld half way up the tank so a double bottom would not help.

 

[salecker]

Just bought 4 Government surplus fiberglass tanks for $400 built in 06 one for my business,going to try and trade one for a Roth tank of the same vintage,it will be going inside my boiler building. I get lots of crappy diesel because i have a waste oil furnace in my shop.Everyone is looking to get rid of waste oil,crappy diesel,old gas,and veggie oil.I filter the crappy diesel and use it in the off season at home,then switch to arctic stove oil for winter backup heat.With the Roth tank i can put it inside my boiler building and not be restricted to warm weather use of the crappy diesel.
I got over 2000 liters of clean diesel this fall all i had to do was pump it out of a couple of tanks.This stuff is so clean it is going to get run through my dump truck this summer.I will get a good weeks work out of it without any fuel expense.

 

[peakbagger]

Funny a prior poster mentioned a bad seam. When I bought my second tank I got it installed and filled then proceeded to find a weeping seam about a halfway up. I had to transfer the contents over to temporary containers and then yank the new one and swap it out. Big PITA.

 

[fire_man]

I had a feeling tanks that failed so soon (less than 10 years) had to be defective construction.

Who cares about a 10 year guarantee on a cheap tank if the cleanup costs dwarf the cost of the tank.