Tanks must be protected from the effects of potential fires. Regional building regulations and British Standards 5410 Parts 1 and 2 state that if a tank cannot be sited the prescribed distance from any hazards, the tank should be protected in one of the following ways:
• construct a suitably sized fire-resistant wall/barrier between the tank and the hazard; or
• if the prescribed distance to a legal boundary cannot be achieved, make the boundary wall fire resistant; and/or
• if the prescribed distance to a non-fire rated building/building opening cannot be achieved, make building walls imperforate (no openings) with suitable fire resistance to internal fire.
The degree of fire resistance needed and the minimum distance that a fuel storage tank can be sited from buildings/boundaries, depends on the capacity of the tank and the type of building that it serves. The OFTEC Field Guide summarises these requirements for domestic sites. Details for non-domestic sites can be found in the technical manual.
What materials/construction types are suitable?
Only materials that will be stable, maintain integrity and provide thermal insulation for the required time period (either 30, 60 or 120 minutes). This is not a matter of guesswork. The material selected needs to have been tested to the relevant parts of BS 476-21, or BS 476-22, or BS EN 1363-1 or BS EN 1364-1. The material must also be declared as suitable for exterior use and should be robust enough to last the lifetime of the tank installation.
OFTEC would always recommend that fire protection barriers should be constructed from suitable masonry or concrete materials, as these have proven and documented fire resistance and weathering properties.
When alternative materials are being considered, OFTEC advises registered technicians to proceed with caution. Prior to selection and use, confirmation should be requested from the product manufacturer/supplier confirming that it is suitable for external use, has been tested to the standards above and offers the minimum period of fire resistance needed.
If I choose to use fire boards, how should they be installed?
In the same way that they were tested by the manufacturer.
It is helpful to understand how manufacturers have their products tested to achieve a 30, 60 or 120-minute fire rating. This test involves exposing one side of a test sample to intense radiated heat to replicate a fire while measurements and observations are made on the unexposed side. Typically, the manufacturer will build a frame, mount a sheet of fire board on both sides of the frame and may sandwich insulation within the frame between the boards. This composite panel construction may pass the test even if the sheet of fire board exposed to the heat source is significantly damaged and the frame behind it is badly charred. A pass result is possible because temperature checks and observations are taken from the unexposed face.
If a registered technician were to select a board tested as part of a composite panel, but only use a single sheet of board on a frame of their own design, they could clearly not be confident of providing a suitably fire rated barrier, as the board has not been installed in the same way as it was tested.
Can a firewall/barrier contain combustible material such as timber?
Yes, but only if this is the material specified in the fire board manufacturer’s installation instructions e.g. timber studwork.
Can a completed fire wall/barrier adjacent to a tank be supported on timber posts?
No. BS 5410-1 states that combustible material should not be used to create a structure that supports the completed firewall/barrier.
Can I attach fire boards to a non-fire rated building/structure or boundary fence to make them fire rated?
No. A structure that does not have the necessary fire resistance (a boundary fence or shed, for example) will be unable to support the fire board for the required period of fire resistance.
What about eaves?
Fire protection cladding can be attached to non-fire rated eaves at domestic dwellings to achieve 30 minutes fire protection. This is possible because the objective is to protect the eaves should the fuel storage tank be set alight. As above, installers cannot presume that a single sheet of fire board will be sufficient for this purpose.
Can I use a metal sheet alone, instead of fire board?
No. A metal sheet alone will not provide adequate thermal insulation.
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