Above Ground Oil Storage Tanks (PPG2)

7. Ancillary equipment

These are the fittings and pipework that all tanks will have, e.g. a vent pipe, but others may be needed according to the tank type, location or use.

For example:

  • a heating oil tank may have a fixed draw off pipe;
  • a tank used for refuelling may have a pump and flexible hose to deliver oil;
  • a tank with a remote fill point or in a sensitive location may have an overfill prevention device.

Ancillary equipment, e.g. valves, filters, sight gauges, vent pipes, must be within the secondary containment system so any discharges of oil are retained.

Many of these fittings are shown in Figures 1 and 2 above and are discussed below. An oil tank user guide ‘Get to know your oil tank’, might also be useful to you, Reference 17.

a) Measuring tank contents
You need to be able to measure how much oil is left in your tank so you can order the right amount when your tank needs refilling and to monitor how fast you use your oil. There are many products available to measure tank contents including electronic, float and hydrostatic gauges, sight or visual gauges and dip sticks. Some are read at the tank others remotely. Ask the tank manufacturer or a qualified competent tank installer for advice on a suitable system for your tank. If storing flammable liquids (as classed by Health and Safety Executive (HSE)), your gauge should be safe for use with the product you store.

Sight gauges

  • must be located in the secondary containment;
  • must be properly supported so it can't come loose;
  • must be fitted with a valve that closes automatically when the gauge isn’t in use;
  • valves should never be kept open;
  • valves should only be opened when taking contents' readings.

Delivery drivers should close sight gauge valves at the end of their delivery. After your tank has been filled, check that the sight gauge is shut and isn’t leaking. Sight gauge tubes aren’t suitable for use with integrally bunded oil tanks.

Dipstick - only use it in the tank for which it is intended.

b) Pipework

All pipework should be:

  • made of a material suitable for use with the oil you’re storing;
  • supported so it’s secure and can’t come loose;
  • positioned or protected to minimise the chances of damage by impact or collision;
  • protected against corrosion;
  • where appropriate, insulated to prevent freezing up and frost damage.

Vent pipe
This allows oil vapour and air to escape from the tank when it is being filled and allows air in when fuel is being drawn off.

We recommend that tanks (including those in buildings) are installed so that vent pipes can be easily seen during deliveries; and that the vent pipes are within and discharge into the secondary containment system.

Legal requirements:

OSR England OSR Scotland
Vent pipes must be arranged so that any discharge is directed vertically downwards into the bund. Vent pipes (including those on tanks within buildings) must be within the secondary containment system.
The tank must be fitted with an automatic overfill protection device, if the filling operation is controlled from a place where it is not reasonably practicable to see the tank and any vent pipe. The tank must be fitted with an automatic overfill protection device (which may include an alarm sounding device) if the filling operation is controlled from a place where it is not reasonably practical to observe the tank or any vent pipe.

Fill point
The fill point is where the tanker delivery pipework connects to fill the tank. There are different arrangements depending on tank type, size and location.

Coupling - If your tank fill point has a serviceable screw fitting or other fixed coupling, it must be used when filling the tank. The fill point should have a lockable fill cap with a chain and be marked clearly with the product type, tank capacity and, where appropriate, tank number. The cap should be replaced to the pipe after each delivery to protect it from damage and unauthorised use.

Position - we recommend your fill point should be at the tank and within the secondary containment system (OSR England only) or in a suitable cabinet with a drip tray to catch any oil spilled during deliveries. Where your fill point is outside the secondary containment system, a drip tray must be used to catch any oil spilled during deliveries.

Fill point drip trays should be:

  • clean, free from water and other debris before each use;
  • large enough to hold all the oil that could be lost when the fill point shut off valve has been closed and the delivery hose is disconnected;
  • able to be moved without risk of spilling the oil - we recommend your drip tray holds at least 3 litres, but it may need to be larger;
  • checked after each delivery and if necessary safely emptied before being put away; we recommend you ask your oil delivery company to do this for you;
  • kept somewhere safe where they can’t collect rain water when not in use.

Remote fill - if there's no alternative and you have to have a fill point which isn't near the tank (or it isn’t practical to see the tank and vent pipe), a remote fill point will be needed. Your registered, competent tank installer (see Section 15) can advise you about standards required for remote fill points. If you have a remote filling point and the vent pipe can’t be seen during delivery you must have an overfill prevention device.

Shut-off valves should be fitted to extended fill pipes because they can retain oil after the delivery.

If you have more than one tank - provide separate fill pipes for each tank, unless they're connected by a balance pipe with a greater flow capacity than the fill pipe. Each fill pipe should have its own fill point shut off valve, and be marked with its corresponding tank/compartment number, volume and type of oil.

Pipework to take oil from your tank (draw-off or supply pipe)
The general points above apply. Whenever possible, site supply pipework above ground to make it easier to inspect and repair. We recommend using tanks that have top outlet off take pipes; and that feed lines should have anti siphon and isolating valves to prevent the tank contents draining down because of leaks, damage, theft or vandalism.

Use pumped dispensing from oil storage tanks for refuelling to reduce the chance of oil spills. If you can’t avoid gravity dispensing then tanks should be properly supported and installed. Suitable secondary containment for the tank and its ancillary equipment should be designed to reduce the chance of oil 'jetting' from the high tank in the event of an overfill or damage.

Consider the risk to the user from working at height (to fill, inspect, maintain and draw-off), suitable ladders, railings and other health and safety equipment may be necessary.

Filters or isolating valves used to protect the draw-off pipe or downstream equipment in a gravity-feed system aren’t considered ancillary to the container. Where practicable, locate this equipment within the secondary containment system. We recommend that valves should be lockable or have removable hand wheels.

Flexible delivery pipes
These should only be used where you need to move the end delivery point, for example when fuelling vehicles. Fit the pipe with a tap or valve at the delivery end, which closes automatically when not in use; we recommend you use a trigger nozzle designed to dispense oil. Where the pipe isn’t fitted with an automatic shut-off device, it mustn’t be possible to fix the tap or valve in the open position. The pipe must either:

  • have a lockable valve where it leaves the tank which is locked when not in use and be kept in the secondary containment; or
  • must be in an enclosed secure cabinet which is locked shut when not in use and has a drip tray.

Dispensing pumps should be:

  • positioned to minimise the risk of damage by collision;
  • fitted with a valve in its feed line that prevents the tank contents emptying if there’s damage to the pump or feed line;
  • protected from unauthorised use.

Pumps are not ancillary to the oil tank. You should ensure any oil that could leak from a pump is contained either by a bund or drip tray. Pumps for oil with a flash point below 55oC should never be within the secondary containment system because of the risk of explosion. If your pump is within the secondary containment, check it's positioned above the 110% containment level so it can’t become submerged.

Underground pipework
These should be avoided where possible as they can’t easily be checked for damage or leaks and have a greater risk of causing pollution. You should only use underground pipe work where you can’t fit pipes above ground. If you do have them we recommend they should:

  • be double skinned pipes
  • be within concrete ducting
  • have as few joints as possible
  • be marked clearly on site plans and when possible on the ground.

Underground pipework must also be protected against corrosion and from physical damage like that caused by excessive surface loading, ground movement or ground disturbance. If mechanical joints have to be used, they must be readily accessible for inspection under a hatch or cover. Keep a record of the test results and any maintenance work completed.

You must have adequate facilities for detecting leaks from underground pipework. If you use a continuous leak detection device, it should be maintained and tested regularly (in Scotland at least every 5 years).

If you don’t have a continuous leak detection system you must test:

  • pipework before use
  • pipework with mechanical joints every five years
  • all other pipe work at least every ten years.

These are minimum requirements and it's good practice to do this more frequently.

c) Overfill prevention devices
We recommend the use of overfill prevention devices to safeguard against spills. These can be electronic or mechanical which either sound an alarm and/or give a visual warning or automatically stop the oil delivery into the tank. They may be a legal requirement depending on tank location, fill point and vent pipe arrangements.

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