Minimum safe tank thickness

dh1989

I purchased an ultrasonic thickness tester to sound my 275 gal basement oil tank. I checked the bottom seam and am reading 2.1 mm. Top of the tank reads 2.2mm. House was built in 1968 and I'm not sure if the tank is original.

I assume this is a 14 ga tank. What is my minimum safe thickness before I need to worry about replacement?

Thanks.

Zman

It sure looks like you are close to spec.

http://www.mesteel.com/cgi-bin/w3-msql/goto.htm?url=/info/carbon/thickness.htm

How accurate do you think the tester is. Is it effected by the oil?

dh1989

Supposedly accurate to .1mm. Not sure if the oil affects it in any way. The tank is about 1/8 full and I took readings all over.

icesailor

If its an indoor tank, in a reasonably warm place, its probably a 45+ year old original tank.

How much did the thickness tester cost? More than a new tank?

Some jurisdictions require a tank that old be replaced. Whether it leaks or not.

IME, tanks don't leak like you think. They either develop a rust spot "pimple" around the bottom, or start weeping on a seam or weld. In 1968, about anyone could build and sell residential oil tanks. By the 1980's, few were because of more stringent regulations and insurance issues. There were some really cheap and bogus tanks out there. Not now.

dh1989

Tester was $100. It's a chinese one but I calibrated it and tested it on various pieces of sheet metal I checked with calipers. Appears to be accurate.

Tank has some light surface rust. The only leakage I see is an old sticky stain from what looks like spillover from the vent connection (overfilled in the past?). It's not an active leak as everything has been dry since I filled the tank back in November.

Tank: http://s1.postimg.org/v0ms0obfj/IMG_3727.jpg
Bottom: http://s21.postimg.org/ly9ee0ow7/IMG_3724.jpg
Outlet: http://s2.postimg.org/xbfboaecp/IMG_3725.jpg

Just some cobwebs underneath and some dried oil from the old vent leak. Cleaned the surface with a paper towel before I sounded it and I didn't see any 'pimples' or questionable areas.

Looks like a 60s era tank?

DocTM

For a standard fuel tank in your basement or garage; I have one forty years old and I wonder what’s the standard thickness of the tank?

EBEBRATT-Ed

12-gauge steel I believe. Some older ones were 14 gauge and I have herd they were 16 gauge in the old days. Don't know if that is true. It should say on the name tag what it is made of and thickness. 12 gauge =0.105"

EdTheHeaterMan

I remember purchasing oil tanks when you needed to specify if it was going to be used indoors or outdoors. You could get away with a UL listed 14 gauge tank in the basement. Outdoor tanks must be 12 Gauge.

Does anyone even make 14 gauge tanks anymore?

EBEBRATT-Ed

@EdTheHeaterMan

Don't think 14 gauge is legal any longer