ArticleThis article provides a detailed introduction on the topic of fuel oil leaks. Our mechanical engineers provide an explanation of the common reasons these leaks occur and information on relevant installation, maintenance, and delivery practices.
The experts at Robson Forensic are frequently retained to investigate incidents where fuel oil is spilled, systems leak, or tanks rupture. Mechanical engineers specializing in building systems are commonly tasked with determining the cause of a failure, while our environmental experts are regularly retained to evaluate the environmental and health impacts. Robson Forensic can provide a complete investigation of your case, scaled to the size and scope of the loss.
Fuel Oil Tank Installation, Maintenance, and Delivery Practices
Spills can occur when tanks are improperly filled or when deliveries are made to the wrong location. Leaks can occur due to improper installation or a lack of maintenance. These spills can cause property damage, soil contamination, and loss of heat which can lead to freeze-ups and water damage. A spill that occurs in a basement can flow through a floor drain or crack and contaminate the environment. Spills from outside tanks can contaminate groundwater, storm water drains, sewers, and adjacent properties. Often, this can cost tens of thousands of dollars to correct. This article provides an overview of heating oil tanks, piping, and accessories and what can be done to avoid costly leaks and spills.
Oil storage tanks include a fill line, a vent line that terminates where a delivery person can see it, a tank level indicator, and/or an overfill alarm, such as a vent whistle. As oil is pumped into the tank, the vent whistle makes a whistling noise until the tank is full. When the whistling sound stops, the delivery person should stop the flow of oil into the tank. Before an oil heating company delivers oil for the first time, it should inspect the oil tank and oil system piping. Any system components that cannot be inspected (such as underground storage tanks and underground piping) should be evaluated by questioning the property owner and checking surrounding areas for evidence of leaks.
It is recommended that all tanks should be thoroughly inspected and approved for delivery by the fuel truck driver/technician before the first delivery is made to a new customer or a new tank.
The initial inspection should include the following:
- Verification of the proper delivery address and fill line location.
- Condition of the tank, oil supply lines, filter, fill pipe and vent pipe.
- Tank gauge is properly installed and accurate.
- Fill and vent pipes are positioned to avoid buildup of water and snow, and fill cap is in place and in good condition.
- Vent pipe is correctly sized, free of obstructions, and vent cap is not clogged or blocked.
- Vent alarm is installed and working.
- Are any compression type fittings installed in copper fuel supply piping? Compression fittings are not recommended for oil piping and should be replaced with flanged type fittings.
Tank inspections should be conducted as an integral part of preventive maintenance. In addition, oil delivery personnel should perform a visual inspection before and after each delivery to check for obvious problems, leaks or obstructions with tanks, fill and vent pipes and caps, oil lines, tank gauges, and vent whistles. They should also check current delivery volume against previous deliveries.
To ensure a safe fuel delivery process and minimize the risk of spills, delivery personnel should do the following:
- Check the size of the vent line before filling the tank. If the line has a diameter of less than 1-1/4”, it may be necessary to change the pumping procedure either by using a loose fill connection or by reducing the pumping rate in order to avoid over-pressurizing the system.
- Start pumping slowly. Before pumping a maximum of 10 gallons of oil, a good vent whistle should have been established. If the whistle cannot be heard or doesn’t sound right, stop the delivery immediately.
- Keep the vent line in view during the entire pumping process. Do not leave the fill pipe while oil is being pumped.
- Stop the flow of oil immediately when the vent whistle stops.
In some of the cases Robson Forensic has investigated, oil leaks and spills resulted due to delivery personnel not following proper filling procedures and not checking fill and vent lines for obstructions. If the vent line is undersized and the tank is filled too fast, or if the vent line is obstructed, then over pressurization of the tank can occur during filling and cause the tank to rupture. When a tank ruptures, hundreds of gallons of fuel may quickly leak onto the property, causing extensive property damage and the need for an expensive environmental remediation.
Oil Tank Installation Considerations
AII oil heat equipment must be installed in accordance with manufacturer’s instructions, NFPA codes, building codes, and the regulations of the local authority having jurisdiction. The following are some general recommendations.
- Tanks should not be placed within 5 feet horizontally from any source of heat.
- Tanks should be equipped with a gauging device to indicate the fuel level in the tank.
- Fill and vent pipes should terminate outside the building no less than 2 feet from any building opening, be fitted with weatherproof fill and vent caps, and be located sufficiently above ground level to avoid being obstructed by snow or ice. Vent pipes should terminate above the fill pipe.
- All tanks should be equipped with a vent alarm (whistle).
- Tanks should be installed indoors whenever possible. This reduces the temperature swings that the tank is subjected to and in turn reduces condensation of moisture inside the tank, reduces degradation of the fuel, and reduces the chance of frozen oil lines.
Maintenance and Corrosion Prevention
Corrosion or rust is a common cause of tank failures. It can occur either externally or internally to the tank. External corrosion occurs mainly in underground tanks due to electrical activity that occurs between the outside of the tank and its surrounding environment. Underground tanks and buried piping should be protected by cathodic protection, corrosion-resistant coatings, special alloys, or fiberglass-reinforced plastic. Internal corrosion is driven by the presence of water in the tank bottom. Bacteria live in the water, feed on the oil and produce a biologically active sludge that corrodes the steel. This sludge can also get into the piping, filters, pumps and nozzles causing oil burner breakdowns. Tanks that are installed near an ocean coastline are even more susceptible to corrosion due to the presence of salt in the ocean air. The solution to the internal corrosion problem is simple –minimize the accumulation of water in the tank. When water is found in tanks, try to determine where it’s coming from and correct the problem. Some possible causes of water getting into tanks are:
- Loose, missing, broken or corroded fill and vent pipes and caps.
- Fill or vent pipes that are too low to the ground and are occasionally under snow or water.
- Broken tank gauges.
The most common cause of water in tanks is condensation of moisture in the air. This occurs when relatively warm outside air enters the tank through the vent and later cools inside the tank, causing the moisture to condense. Although condensation cannot be avoided completely, several things can be done to minimize the accumulation of water and risk of corrosion in oil tanks:
- Install tanks indoors whenever possible. If a tank must be installed outside, protect it with an enclosure designed for outdoor oil tanks. Outside tanks accumulate significantly more water from condensation than inside tanks because they are subject to wider differences in temperature.
- Make sure new tanks are fully drained before installation. Many tanks accumulate significant amounts of water during storage and shipment, even when plugs are placed in openings.
- When an old tank is replaced with a new tank, never transfer fuel from the old tank to the new tank, since old tanks are likely to contain water and sludge, leading to premature tank failure.
- Tanks provided with an opening at the bottom for the burner supply connection should be sloped toward the opening at a slope of not less than 1/4 inch per foot of length to facilitate any accumulated water to flow out of the tank.
- Use fuel additives containing a water eliminating agent.
- Keep tanks full during the non-heating season. Although this allows more time for the fuel’s natural aging process, which degrades the fuel over time, it greatly reduces condensation of moisture inside the tank.
- Routinely check tanks for water accumulation during service calls and tune-ups. Apply water finding paste to a tank stick and fully insert it until it touches the bottom of the tank. If water is present, the paste changes color to indicate how many inches of water are at the tank bottom. Pump or drain the water out until clean oil flows.
- When servicing cartridge type filters, it is very important to thoroughly wipe out the inside of the filter housing with a clean cloth and inspect it for corrosion. Replace it if pitting or other signs of corrosion are found. Even a small 1/16 inch diameter hole from pitting can leak a few gallons of oil per hour. If left undetected, hundreds of gallons of oil could leak out over the course of a few days.
Doing routine maintenance and eliminating any accumulated water can greatly reduce the risk of corrosion. If accumulated water isn’t regularly removed, it will dramatically shorten the life of the tank. Properly installed and maintained oil tanks should have a life expectancy of 20 to 30 years. While many tanks can last much longer, it’s much better to replace a tank too early than too late.
BUILDING SYSTEMS INVESTIGATIONS
Building systems refers to the mechanical (HVAC), electrical, and plumbing systems found in modern buildings. Our experts are frequently engaged in cases involving design and installation errors, product malfunctions, as well as maintenance and operations issues.
For more information visit our Building Systems practice page.
The environmental experts at Robson Forensic are engaged when individuals or the environment are exposed to potentially hazardous materials. The scope of our investigation varies from case to case, but can include a thorough review of processes, storage and transportation protocols, disposal procedures, incident response and remediation plans, and much more.
For more information visit our Chemical Spill practice page.
David Caggiano, P.E., C.F.E.I.
Daryl J. Smith, P.E.
Ronald J. Natoli, P.E., C.F.E.I.
Stanley Jaworski, P.E., C.F.E.I., C.V.F.I.
Dale J. Cagwin, P.E., C.F.E.I.
Edward A. Gray
Rene Basulto, P.E., MSEM, CGC, C.F.E.I.
This article was developed in collaboration with several members of the mechanical building systems practice at Robson Forensic. For cases involving a variety of issues from HVAC, plumbing, and fire suppression systems to the design of fuel burning appliances and other industrial processes, please submit an inquiry or call our corporate office