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Safety and environmental standards for fuel storage sites
Final report
45
Option
Advantages
Disadvantages
Fire resistance Cost**
Poly-ethylene
(HDPE)
Resistant to water,
––
hydrocarbons and most
chemicals
Requires protective layer
––
Potential hidden
––
problems around seals
and penetrations
Base ground to be
––
prepared well, ie remove
stones, requires a layer
of gravel and sand/
geotextile before the liner
Requires specialist
––
installer to weld joints
Very Low
––
Burns readily if
––
unprotected
Medium
Poly-propylene
(PP)
Resistant to water and
––
oils
Easier to lay than HDPE
––
Limited resistant to fuels
––
Requires protective layer
––
Potential hidden
––
problems around seals
and penetrations
Base ground to be
––
prepared well, ie remove
stones, requires a layer
of gravel and sand/
geotextile before the liner
Requires specialist
––
installer to weld joints
Very Low
––
Burns readily if
––
unprotected
Medium
Synthetic
rubber and
EPDM
Resistant to water
––
Not resistant to oils and
––
fuels
Requires protective layer
––
Very Low
––
Burns readily if
––
unprotected
Medium
** Costs are indicative and may vary based on installation issues and scale.
Fire resistance and integrity of pipe penetrations and expansion joints
176 The COMAH Containment policy states that: ‘Bunds shall have fire resistant structural
integrity, joints and pipework penetrations.’
177 Improvements should be made to the fire resistance of bund joints and penetrations where
the existing arrangement has inadequate fire resistance. Options for enhancing fire resistance of
new designs and existing situations where reasonably practical if the risk is tolerable are covered
in the following sections.
178 The objective is to retain the integrity of a bunded area as long as possible in the event of a
fire. Concrete and clay have inherent fire resistance, but the risk of a loss of integrity is provided
by joints and penetrations to the bund walls and floors and the way these features are sealed.
179 Sealants are now available which have enhanced fire resistance. The fire-resistance standards
commonly referenced are BS 476-20:1987
34
and BS 476-22:1987.
35
The maximum fire resistance
quoted in BS 476 is four hours.
180 Tests of fire rated and non fire rated joint sealants in combination with steel plates indicate
that fire rated sealants provide improved fire resistance.
181 In considering the use of fire-resistant sealants, due regard should also be given to the
suitability and compatibility of candidate products (for example hydrocarbon and water resistance)
in the specific application.
182 Waterstops are integral design and construction features of concrete structures whose
duty is to retain liquids. Good practice for the minimisation of leakage from concrete bunds
includes the use of waterstops within movement joints, in accordance with BS 8007. In order to