Want to find out more about British Standards BS 799 Bunded Tanks Specification

The text herein is not a a full reproduction of the British Standard. It is summary based upon interpretation of the original text and not intended as a replacement for the full text. It should be used for general guidance only.

This part of BS 799 gives specification for the requirements for tanks for the storage of liquid fuel, used in conjunction with oil burning equipment, and includes:

  • integral tanks which form part of a complete oil fired unit
  • service tanks
  • storage tanks with a maximum height of 10 m
  • the standard is applicable to tanks constructed of plain carbon steel.

Integral tanks:

  • Integral tanks shall have a maximum capacity of 25 L. Each integral tank shall carry a prominently displayed notice at the filling point to indicate that the tank must not be filled whilst the burner is alight and specifying the type of oil to be used.
  • Each integral tank shall be mounted in such a way as to ensure that when the ambient temperature is 25 or higher the temperature of the oil being stored does not exceed 35 for class C oil or 55 for class D oil.
  • Each integral tank shall be mounted in such a position that any accidentally spilled oil or escaping oil is unable to come into contact with any heated surface.
  • Before being painted each tank shall be pressure tested by the manufacturer. Each tank should be able to withstand the design pressure. The purchaser shall inform the manufacturer of the design pressure. All the pressures to which the tank may be subjected should be taken into consideration. The manufacturer shall provide the purchaser with a copy of the test certificate for each tank supplied.
  • All joints below the fuel full level should be made by welding or brazing.
  • Attention should be paid to the design of the tank so that it can safely be used for the purpose it is intended by providing sufficient strength and rigidity to resist any distortion which may give rise to hazardous release or discharge of oil or vapour. Integral tanks should be resistant to erosion.

Service tanks:

  • Service tanks shall have a capacity of not more than 1000 L.
  • An oil drain valve and, for coal tar liquid fuels, a water drain valve shall be provided.
  • A separate vent pipe or return pipe shall be provided for each tank at the higher end.
  • For oil draw-off lines and where return lines are used, fire valves shall be provided.
  • Before being painted, each tank shall be pressure tested at the manufacturers works or on site when the tank is manufactured on site.
  • Tanks tested on site shall be tested hydraulically.
  • The manufacturer shall provide the purchaser with a copy of the test certificate for each tank supplied.
  • The following information shall be clearly and permanently marked near the outlet connection, on the vertical centre line of the tank:
    • capacity (in L)
    • date of manufacture
    • manufacturer’s name and/or trademark
    • manufacturer’s reference number
    • the number and date of the BS Standard used and the type of tank
  • Service tanks shall be constructed of rolled steel sheets which comply with requirements for grade CR4 material suitable for welding as specified in BS 1449 : Part 1. Galvanized steel shall not be used.
  • Service tanks will be of welded construction.

Oil storage tanks:

  • Tanks shall be provided with an oil level indicator.
  • An oil drain valve and, in addition for coal tar liquid fuels, a water drain valve shall be provided.
  • A separate vent pipe shall be provided for each tank, at the higher end.
  • For oil draw-off lines and where return lines are used, fire valves shall be provided.
  • The Standard as for pressure testing of oil storage tanks is as for other types of tanks, except as regards sectional tanks. Where a sectional tank cannot be subjected to a pressure equivalent to the head of oil in the tank and vent pipe (such as by overflowing) it shall be tested by being filled to its capacity with water. This test shall be maintained for a period of 24 hours.
  • Following testing, each tank should be cleaned internally and externally and then painted externally with a rust inhibiting priming paint.
  • The markings required for this type of tank are the same as those specified for service tanks.
  • Storage tanks of capacity not more then 3500 L shall be of welded construction and made of rolled steel sheets which comply with requirements for grade CR4 material suitable for welding as specified in BS 1449 : Part 1. Galvanised steel shall not be used.
  • Storage tanks of a greater capacity shall also be of welded construction but shall be made of rolled steel plates which comply with the requirements for grade 43A material as specified in BS 5135.

A British Standard nor this summary does not, necessarily, include all the necessary information for correct implementation of the Standard to any specific application. This is purely the responsibility of the user. Standards are updated by either amendment or revision. Users should ensure that they are using the latest version.