Free Encyclopedia of Building & Environmental Inspection, Testing, Diagnosis, Repair

Ask a Question or Search InspectAPedia

• HOME
• AIR CONDITIONING
• ELECTRICAL
• EXTERIORS
• HEATING
• HOME INSPECTION
• INTERIORS
• PLUMBING
• ROOFING
• SEPTIC SYSTEMS
• STRUCTURE
• WATER SUPPLY

• ENERGY SAVINGS
• ENVIRONMENT
• INDOOR AIR IAQ
• INSULATION
• MOLD INSPECT TEST REMOVE
• NOISE
• ODORS
• SOLAR ENERGY
• VENTILATION
• EXPERTS DIRECTORY
• CONTACT US

Heating Oil Underground & Above ground Oil Storage Tank Life Expectancy InspectAPedia®  -     Life expectancy of buried or above ground oil tanks Factors affecting oil tank life: indoors, outdoors, or buried tanks How long does an oil storage tank last? Questions & answers about typical oil storage tank life and factors that affect oil tank durability and leak risk

This article discusses estimates of oil storage tank life for buried oil tanks and above ground oil storage tanks and reviews the factors that affect oil tank life. How long an oil storage tank can be expected to reliably contain its oil and not to leak depends on quite a few variables which we discuss here.

Also see OIL TANK FAILURE RATES and if your oil tank is leaking see OIL TANK LEAK ADVICE.

Some things that can shorten the life of an oil tank can be avoided or corrected. The photo shows how a leak develops and appears in an indoor oil storage tank, forming a stalactite of oil and sludge hanging from the bottom of the tank. Because an oil tank often rusts through from the inside out, the exterior of an oil tank may look fine but in fact it could be paper thin and easily punctured, even by a finger!

The life expectancy of oil tanks is helpful in planning for storage tank testing and storage tank replacement. This is a chapter of our "Heating Oil Underground & Above ground Oil Storage Tank Leaks, Testing, Problems & Solutions, Home Buyer's / Home Owner's Guide" which offers extensive free un-biased oil storage tank inspection and testing advice for property buyers and owners.

Home buyers should be sure to review OIL TANK TESTING - Leaky Heating Oil Tanks - How Oil Tanks are Tested for Evidence Leaks, of Current or Previous Oil Spills and OIL TANK LEGAL ISSUES - Home Buyers and Home Owners Guide to Leaky Heating Oil Tanks - What to Do About & When to Report Oil Tank Leaks. Leaky Heating Oil Tanks.

Home owners who have old oil tanks above ground or any age oil tank below ground should also be sure to review OIL TANK ABANDONING PROCEDURE - Abandoning Commercial vs. Residential Underground Oil Storage Tanks (UST) - Procedures & Regulations A separate website addresses Septic Tanks.

© Copyright 2012 InspectAPedia.com, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use page top links to major topics or use links at the left of each page to navigate within topics and documents at this website. Green links show where you are in a document series or at this website.

OIL TANK LIFE - Life Expectancy of Buried or Underground Oil Tanks

While we've found them lasting longer, a common life expectancy of buried oil tanks is 10-15 years. At about 20 years, the risk of leaks from buried steel oil tanks becomes significant. Leaks can occur earlier if a tank was damaged at installation or was not properly piped.

Even if you think the tank is ok, young, and not leaking, buried oil tanks, should be tested for water in the tank bottom. Water should be pumped out since it corrodes the tank and leads to leaks. Oil tank leaks can also be due to damage at time of installation, improper installation, corrosive soils, or piping defects. If the tank is to remain in use, ask your fuel supplier about using an additive or other methods to help remove water.

Life Expectancy of Buried Oil Storage Tanks - Residential

In New England for a two year period [1984-5] among customers who have buried heating oil tanks (16% of total customers) surveyors found an average of 1.7 tank leaks per thousand customers. They also found 2.5 fuel line leaks per 1000 customers. (Fuel Oil and Oil Heat magazine, August 1985 p.18.) We do not have similar data for buried gas tanks in residential application.

Also see Leak or Failure Rates for Home Heating Oil Tanks.

Life Expectancy of Above Ground Oil Storage Tanks - Residential indoor or outside

We have not seen current research data on indoor oil storage tank life, and we suspect that there is a wide variation in indoor above ground and outdoor above ground oil tank life due to the considerable variation in both the quality and thickness of oil tank steel (older tanks seem to have been a heavier gauge steel), as well as other factors in oil storage tank life.

We have seen indoor oil tanks easily in good condition that are 60 years old or older, and we have found failures in newer oil storage tanks that may have been made of thinner or cheaper steel and that did not last as long as the original ones.

Rather than guess at oil tank condition, we suggest that if your home has an older above ground oil storage tank, ten years old or older, you should

• Make a simple visual inspection of the oil tanks and piping for leaks; light external rust is not usually a problem - oil tanks usually corrode and leak from the inside, and usually in the bottom 1/4 of the tank; See these articles:
  • OIL TANK DEFECT INSPECTION
  • Above Ground Oil Tanks: Visual Inspection of Oil Storage Tanks for evidence of leaks, damage, improper piping - photos and text
  • Above Ground Oil Tanks Checklist, an Oil Company's advice
• If the oil tank is leaking, see Leaky Heating Oil Tanks - Advice for Home Owners or Buyers: caused of leaks in oil tanks, oil tank testing alternatives, what to do about leaky tanks: D. J. Friedman, ASHI Tech. Journal, Vol.2 No.1, Winter, 1992 p. 42-43 Illus
• Have the oil tank steel tested for soundness - see OIL TANK TESTING - if the tank is not sound, have it replaced.
• Check the oil tank piping for leaks, soundness, proper oil tank vent size. See OIL TANK PIPING & PIPING DEFECTS.
• If there is evidence of water or sludge in the oil tank, ask your oil company to pump out sludge or water; see OIL TANK WATER CONTAMINATION or OIL TANK SLUDGE.
• If sludge has been clogging your oil filters, double the oil filter size and quantity (install two filters in parallel) so that you can get from one annual heat service call to the next without a no-heat call due to clogged oil filter. See OIL TANK SLUDGE.
• If you have to install a new tank and there is not room to place a tank indoors, we recommend building a cover ofer the oil tank to protect it from weather and to permit heating the tank enclosure just enough to keep it above 35 degF.
  
  We prefer to avoid outdoor tanks because of the risk loss of heat due to water, ice, or fuel waxing, OR because the owner has to pay more for heat by having to burn kerosene mix or add pour point depressants at each oil fill-up)
  if you have to to to an outdoor tank, enclose it and give it a little heat is the best installation.

Thanks to reader Robert Frank for suggesting a discussion of indoor oil storage tank life.

Factors in Oil Storage Tank Life and Oil Leak Occurrence

Above Ground Indoor Oil Storage Tanks

• The first tank shown here has seepage at its fill and vent fittings, a rather typical and trivial problem which is hard to avoid unless meticulous sealant application is used during assembly of the fill and vent piping - the machining at the tank top and on larger diameter piping is often a bit rough. The second tank shown here is an older one which shows the same seepage around the tank top fittings. But what about those oil stains on the lower left tank body? The tank may be leaking at its seams or from perforations. Further investigation is warranted.
• Water accumulating in the tank from bad oil deliveries or from wide temperature swings and in-tank condensation. Test the tank for water and remove water from the oil tank by pumping (large amounts) or by absorbing chemicals or pads (small amounts of water).
• Poorly-made plumbing connections. Inspect and correct any leaky fittings.

Above Ground Outdoor Oil Storage Tanks and Life Expectancy Factors

Include the causes listed above and add the following oil storage tank life determining factors:

• Exposure of the oil storage tank to wider temperature swings, especially in cold and humid climates can increase in-tank condensation
• Exposure of the tank filler or vent pipes to rain, especially to roof runoff for tanks mounted under the eaves of a home and especially if a proper cap is not kept on the tank filler pipe or if the vent pipe is not properly installed and shielded.
• External oil tank rust due to exposure to the weather. Many small tanks, 250g or 275g, were never rated for outdoor use, as you may easily ready by examining the embossed UL label affixed to most tanks. Manufacturers of newer oil storage tanks in this size range appear to have removed this "indoor use only" wording from the UL label, as you can see in the photo shown here. We have not learned whether the standard was changed, the tanks were changed, or simply the label was changed. An outdoor tank should be protected from the weather and in freezing climates should be given shelter and warmth.
• Improper oil tank installation / installation of improper oil tank type: the second photo above shows an old, indoor-oil tank which was moved outside and placed onto the soil surface below a deck, and then was half buried. What is this tank, a buried tank or an above ground tank? It was not rated for outdoor use at all and is at extra risk of leakage due to placement of the tank body directly in contact with the soil.
• Improper oil storate tank supports, such as failure to keep the outdoor tank off of the ground, to install it at the proper pitch and direction of pitch, and to install it on level, secure piers can lead to a tank tipping over, ripping open an oil line, and obvious catastrophes of oil spillage and heat loss.

We discuss the inspection of above ground oil storage tanks at ABOVE GROUND OIL TANK INSPECTIONS.

What Determines the Life of Buried Oil Storage Tanks

Include the causes listed above and add the following: Exposure of the tank filler to surface runoff (as shown in the photograph): some oil tank installers or homeowners insist on installing the tank filler flush with or even below ground level, perhaps for aesthetic reasons. This detail increases the risk of snow melt or surface runoff entering the oil storage tank, particularly if the filler cap is left off or if its o-ring or gasket seal is not perfect. Smaller tanks which have been buried, such as a 250g or 275g tank, especially if more than 10 years old, are suspect: we have not ever found one of these that was labelled as approved for outdoor below-ground use. If you have a buried oil tank in this size range further investigation is warranted. Mechanical damage to the tank during installation, such as scraping its protective coating (if there was one), or omission of any protective coating on the buried tank. Damage might occur for example, by scraping the tank with equipment used to move it, or by setting the tank into a hole atop a rock or other debris. Fiberglass or plastic tanks may be more vulnerable to serious mechanical damage during installation. Corrosive soils - soil corrosivity may be a significant factor in buried steel oil tank life in areas of soils with a high corrosivity index. Plastic or fiberglass tanks are less likely to be affected by soil corrosivity. Amount of ground water in soil: wet soils increase the risk of corrosion on buried steel tanks and increase the risk of leaks into a damaged (or poorly plumbed) tank for both steel and plastic/fiberglass oil storage tanks.

Questions & Answers regarding this article

Questions & answers about typical oil storage tank life and factors that affect oil tank durability and leak risk

Question: I've seen claims that oil storagte tanks last even up to 40 years - who's right?

Hi

I refer to one of your article on your website (above on this page), which I am curious and very much want to know more. Are there justification to that? Or it depends on other parameters such as weather and soil conditions? Some websites mentioned that such tank can last even up to 40 years. - M.A., PUB, Singapore National Water Agency

Our InspectAPedia photo of an abandoned "buried" oil tank shown at left is an example of a buried oil storage tank that had a very long and leakproof life - until it was abandoned, forgotten, and left empty. Worse the tank had been buried alongside a waterway - a stream in Rhinebeck, NY. (Details are at FLOATING UP OIL STORAGE or SEPTIC TANKS)

This oil tank was subjected to very wet soil conditions over several decades, apparently without leaking oil into the environment. But we can't promise the same performance for all buried tanks. It depends ...

Reply: how long do buried oil tanks last ? ... It depends

If you have reason to need an oil storage tank that is resistant to corrosion damage, take a look at some of the fiberglass and other plastic alternatives as well as (more costly) multi-walled oil storage tanks that are required in some jurisdictions and applications.

Watch out: about "up to" claims.

Finally, whenever you see someone claiming "... up to ..." you don't really know what to make of such remarks. "Average life of an oil storage tank" is nothing like "... up to... " life. "Up to" after all, could include one single instance of an oil storage tank that was reported to be 40 or 60 or some other age. And meaningless.

Consulting with an advertising attorney last year we learned that there is a legal definition of "up to" claims - at least in advertising case law. You can claim "up to" for a product if 10 percent of the product meets that standard. So if one oil tank lasted for 40 years somewhere but another nine in the same test set all failed in the first month of service (certainly not really likely), the tank "expert" could still claim that his oil tank installations lasted "up to 40 years".

I appreciate the question and welcome reports of oil tank life from folks in other countries and environments. We are dedicated to making our information as accurate, complete, useful, and unbiased as possible: we very much welcome critique, questions, or content suggestions for our web articles. Working together and exchanging information makes us better informed than any individual can be working alone. InspectAPedia is an independent publisher of building, environmental, and forensic inspection, diagnosis, and repair information for the public - we have no business nor financial connection with any manufacturer or service provider discussed at our website.

Share this Article      

...

Technical Reviewers & References

• InspectAPedia.com^® - Daniel Friedman - Publisher & Editor.
• InspectAPedia Bookstore lists recommended books, organized by topic & available for purchase. Most of our articles also include a list of recommended books for the specific article topic as well as other references, and information sources.
• Critique, contributions wanted: Contact Us to suggest corrections or additions to articles at this website, and if you wish, to receive online listing and credit as a contributor. Particular thanks are due to the many experts and also consumers who read and critique technical articles at InspectAPedia.com.
• Additional technical contributors & reference sources for this article are listed below.

Use links just below or at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

OIL TANK LIFE

• The rate or frequency of oil tank leaks or oil storage tank failures, focused on underground storage tanks or USTs, is discussed in detail at TANK FAILURE RATES Oil Tank Failure Data - Oil Tank Failure Rates - Oil Tank Leak Probability as a Function of Tank Age, Location, Condition, Soil Conditions and Other Factors. TANK REGULATIONS outlines who, when, and how oil leaks and spills must be reported to environmental authorities.
• Thanks to Robert Frank for email discussion about oil storage tank life, 1/21/2010

Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair

• Our recommended books about building & mechanical systems design, inspection, problem diagnosis, and repair, and about indoor environment and IAQ testing, diagnosis, and cleanup are at the InspectAPedia Bookstore. Also see our Book Reviews - InspectAPedia.
• "How do you choose the right tank testing method?", Cynthia Johnson, Fuel Oil & Oil Heat Magazine, November 1995
• National Association of Oil Heat Service Managers, PO Box 380, Elmwood Park, NJ 07407
• "Homeowners Guide to Fuel Storage," Agway Energy Products, Verbank, NY, November 1990
• Web Link Exchange: Contact Us to list your website or contact information for oil tank testing, tank corrosion research, oil industry experts
• ...