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Safety and environmental standards for fuel storage sites
Final report
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meet both fire and corrosion resistance performance requirements metal waterstops should be
used on new build and where reasonably practical if the risk is tolerable for existing bunds – as
described in paragraphs 209–216.
183 Waterstops are defined in BS 8007 Appendix C3: ‘Waterstops are preformed strips of
durable impermeable material that are wholly or partially embedded in the concrete during
construction. They are located across joints in the structure to provide a permanent liquid-tight
seal during the whole range of joint movements.’
184 Following the Buncefield incident it was recognised that the addition of steel plates to cover
the inside faces of movement joints provided enhanced fire resistance to existing joints. It was
recommended that improvements to existing bunds containing gasoline tanks should be made
by replacing existing sealants with fire-resistant versions and, in addition, fitting steel cover plates
where physically possible to fit. This proposal of the combination of cover plate and fire-resistance
sealant is recommended as good practice retrofit solution for existing installations, where routine
inspection of the sealant is carried out. See paragraphs 205–212 for further information.
185 From the information available regarding waterstops and steel plates, the following
statements are reasonable:
Fire resistance:
Metal waterstops are effective at resisting fire.
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Steel plates are a practical method of greatly enhancing fire resistance and minimising loss of
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integrity to joint materials due to fire.
Leakage:
Waterstops provide the most effective way of minimising leakage from bund joints.
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Steel plates have been seen to significantly reduce leakage rates due to their role in providing
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protection to sealants and vulnerable plastic waterstops.
They have not been seen to be as effective at minimising leakage in the same way as
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waterstops which are integral to the joint design.
Design of steel plate fire protection
Determined by the specific circumstances
of their application. However, the following
general guidance is useful:
material of construction: stainless steel;
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width: minimum 20 cm;
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thickness: minimum 6 mm;
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fixings to bund walls: stainless steel bolts
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through oversized slotted holes.
(Note: Oversize holes cater for vertical
expansion of the plate in a fire, whilst
horizontally slotted holes allow for movement
of the walls where the plate is bolted to both
sides of the joint plates can be fabricated in
short sections to limit the weight when fixing,
with a lap detail to cover plate junctions –
see Figure 3.)
Figure 3
An example of a design with fixing to
one side of the joint only