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Chapter 3Oil Tanks and PipingChapter 3Oil Tanks and PipingIntroductionThe comfort, cleanliness and efficiencyof today’s oilheat systems rely on clean,uncontaminated fuel reaching the oilburner.To achieve this: Install tanks properly. Maintain tanks by regularly inspectingthem and fixing minor defects beforethey lead to major problems. Replace aging tanks before they fail.The proper installation of an oil tank is arelatively easy process, provided it isinstalled in accordance with themanufacturer’s instructions and applicablecodes and regulations are followed.Local codes normally require you toinstall tanks in accordance with either theirown code, the National Fire ProtectionAssociation (NFPA) or the InternationalCode Council (ICC). It’s best to check withthe local authority having jurisdiction todetermine which regulations you need tofollow.This chapter gives an overview of oiltanks; for more detailed information, werecommend that you read NORA’s oil tankmanual, “Heating Oil Storage Tanks, Guidefor Quality Installation and Maintenance.”Why tanks failThe most common cause of failure iscorrosion—the deterioration of the tankdue to reaction with its environment.External corrosion is caused byelectrical activity that occurs betweendifferent parts of the tank; between the tankand its piping; or between the tank andother metals in the area. For externalcorrosion to occur, there needs to be:1. an anode— something to give upelectrons (the tank);2. a cathode— something to accept theelectrical flow (piping, metals in theground, etc.);3. an electrolyte— something for theelectricity to travel through (water).There is not much you can do to preventexternal corrosion in existing unprotectedunderground (buried) tanks. Later in thischapter, we’ll show the types of tanks thatcan stand up to the corrosion factors thatexist underground.To reduce exterior corrosion for aboveground tanks, make sure that: The tank has clearance on all sides sothat debris can’t accumulate and holdmoisture against the tank. There is sufficient clearance under thetank so that plant growth does notcome in contact with it. Scratches and rust are repairedimmediately. The tank is painted on a regular basis.Internal corrosion is caused by sludgeproduced by bacteria. For internal corro-Chapter 3—Oil Tanks and Piping3-3

Chapter 3Oil Tanks and Pipingsion, Figure 3-2, is to eliminate the waterat the bottom of the tank. Removing thewater is just the beginning. You must alsodetermine how the water got into the tankand take corrective steps to prevent waterfrom building up again. Figure 3-3.Figure 3-1: Variouslayers of materialin the tanksion to occur at the tank bottom, thereneeds to be bacteria and water in the tank,see Figure 3-1.The bacteria live at the oil/waterinterface; they “eat” the oil and create asubstance that, when mixed with water,creates an acid that corrodes the metal inthe tank.The best way to reduce internal corro-Figure 3-2:Internalcorrosionwith pin holemagnifiedFigure 3-3: Bacterial “Bug Tracks”The most common causes of waterin tanks are: Condensation Broken tank gauges (outside tank) Loose or missing fill and vent caps Pumping oil from an old tank into anew tank Failing to drain water from a tankbefore installation.Condensation can be greatly reduced byinstalling tanks indoors or in an enclosure.If a tank is located outside, you can reducecondensation by painting it a light colorand protecting it from direct sunlight.Gauges and caps should be inspectedregularly and replaced when necessary.3-4Oil Tanks and Piping

Chapter 3Oil Tanks and PipingFollowing manufacturer’s instructionswhen installing new tanks and performingthe inspection procedures described at theend of this Chapter, you will greatly reducethe amount of water-related problems andextend the lives of your customers’ tanks.Properly installed and maintained tankscan last for several decades—much longerthan most equipment in the home. However, like everything else, tanks eventuallyneed to be replaced.Installation considerationsWhen it is time to install a new orreplacement tank—answer these threequestions: What size tank will be best? Where is the best place to install it? What type of tank will be best?SizeAlthough large tanks are often installedfor delivery efficiency, an oversized tankcan cause service problems—such as: Poor fuel quality—fuel oil has a shelflife and deteriorates over time. Corrosion—larger tanks usually buildup more water from condensation.On the other hand, tanks that are toosmall require frequent deliveries, leading toproblems during peak delivery season.In general, the right size tank is one thatholds about one-third (1/3) of thecustomer’s annual consumption. Therefore,a customer who uses 900 gallons of oil ayear should have a 275 or 330-gallon tank.(900/3 300)There may be special situations thatrequire you to install a tank that is eitherlarger or smaller, but in general, it is bestto apply the 1/3 rule when possible.LocationThere are three possible locations for atank installation:1. Inside a building—usually in thebasement, utility room or garage2. Outside, above–ground3. Outside, undergroundBefore selecting a tank location, be sureto consider regulations regardingsetbacks from: Heating equipment and otherignition sources Property lines Buildings, doors, windows, vents andair intakes MetersAlso remember to locate the tank where: The delivery vehicle can safely parkduring filling It will be accessible for inspectionand servicing An oil release will not easily enter adrain, well or waterway It will not be exposed to corrosionand/or damage from dripping water,falling ice, vehicles, etc.Inside tanksNORA recommends above ground,indoor tank installations whenever possible.These installations offer a number ofadvantages over outside tanks, including: The oil is usually warmer, whichmeans it burns better and won’t gel orhave cold weather performanceproblems.Chapter 3—Oil Tanks and Piping3-5

Chapter 3Oil Tanks and Piping There are fewer temperature changes,which means the oil will last longer. If a leak develops, it will cause anodor, which quickly alerts us to theproblem. It’s easier to inspect. Less condensation in the tank.It is important that you follow codes andinstructions regarding:A. Distance from the tank to the burner(At least 5 feet.)B. Size and height of the vent pipe2. All tanks should have a vent alarm3. All tanks should have a tank gauge4. All systems should have an oil filter;it can be located at the tank, at the burneror at both the tank and burner.5. The copper oil line from the tank tothe burner (shown here running under thefloor) should not touch concrete or soil.This can be done by sliding the copper oillines into plastic conduit or plastic pipe orby using a coated copper line.There should be no fittings in the copperlines below the floor. Figure 3-4.C. Size of the fill pipeD. Fusible valve at the tankE. Fusible valve at the burnerIn addition:Figure 3-4:Typical indoorinstallation1. The fill and vent lines must bepitched toward the tankAbove-groundoutside tanksIf there is no room for a tank inside thebuilding, it must be installed outside, seeFigure 3-5. In these cases, it is a good ideato install the tank in secondary containmentCoated Copper Line3-6Oil Tanks and Piping

Chapter 3Oil Tanks and Pipingthermal shut-off valve.The oil filter shouldNOT be installedoutside. It can beinstalled right after thevalve where the lineenters the building orat the burner.UndergroundtanksFigure 3-5: Outside above ground tankor in an enclosure to protect it from theelements.The outside oil line should be connectedthrough the top of the tank and insulated towhere it enters the building. Once the lineis inside, it should be connected to aEnvironmentalregulations andinsurance concernshave greatly reducedthe number of inground installations,Figure 3-6, and many homeowners withburied oil tanks have replaced them withabove-ground tanks.Unless there is no acceptable locationavailable, NORA recommends that all newoil tanks be installed above ground.Figure 3-6:Typical olderundergroundinstallationVent Line1 ¼" Minimum2" Fill PipeAnti-Siphonor BallCheck ValveInspectionPortSwing JointTeeSwingJoint½" Copper TubingFuel Storage TankValveOil FilterLoop Oil LinesChapter 3—Oil Tanks and Piping3-7

Chapter 3Oil Tanks and PipingTypeOnce you have determined the propersize and location to install a new tank, yourcustomer can choose the type of tank basedon price, warranty and level of spillprotection. There are many choices:Figure 3-7:Ob-roundtankAbove groundtanksOb-round—The 275gallon “Ob-round” steeltank, Figure 3-7, has beenthe standard for decadesand is the most commontank. Ob-round tanks arecurrently available in anumber of sizes fromslightly over 100 gallons to330 gallons.Figure 3-9:Externallycoated tankExternally coated ob-round—Thiscorrosion resistant tank has a polyethylenecoating on the outside of a standard obround tank, Figure 3-9. The coatingprotects the tank from external corrosionand serves as release barrier should thetank corrode internally.Fiberglass—This corrosion proof tankis available in both single and double wallmodels and in 240 and 300-gallon capacities. The double wall unit is a tank within atank— if the inner tank leaks, the outertank prevents a release of oil, Figure 3-10.Figure 3-8:Bottom tapNewer ob-round tanks have the oildrawn from the bottom of the tank toreduce the amount of condensation andsludge build-up in the tank. Figure 3-8.Cylindrical—These tanks are oftenfound in mobile homes and in places wherespace considerations made it easier toinstall and service than an ob-round tank.They are typically available in sizesranging from 160 to 320 gallons.3-8Oil Tanks and PipingFigure 3-10: Fiberglass tank

Chapter 3Oil Tanks and PipingPolyethylene/steel – These double walltanks combine an inner tank made ofpolyethylene with a steel outer tank. Theouter tank protects the inner tank andprovides secondary containment. SeeFigure 3-11.2. Sacrificial anodes that protect the steel3. Nylon isolation bushings that electrically isolate the tank from the fill pipe, ventpipe, oil lines and other attached pipingACT-100 and ACT-100UThese tanks include a much thickerprotective coating and offer protectionsimilar to the Sti-P3 without sacrificialanodes, Figure 3-13.Figure 3-11: Polyethylene/steel tankUnderground tanksFigure 3-13: ACT-100SteelSti-P3—These tanks combine thestrength of steel with a factory installedcorrosion protection system, Figure 3-12.Sti-P3 tanks feature:Fiberglass (FRP)Fiberglass reinforced plastic tanks neverrust because they are made from corrosionresistant materials, Figure 3-14.1. A protective coating over the steelthat prevents external corrosionOnce you’ve determined the right size,location and type of tank to install, youFigure 3-12: Underground steel tankFigure 3-14: Fiberglass (FRP) tankChapter 3—Oil Tanks and Piping3-9