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Safety and environmental standards for fuel storage sites
Final report
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Pipe penetrations: general
186 HSG 176
The storage of flammable liquids in tanks
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states that:
where reasonably practicable electrical equipment should be installed in non-hazardous areas
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... and … where this cannot be done, equipment should be selected, installed and maintained
in accordance with BS 5345
Code of practice for the selection, installation and maintenance
of electrical apparatus for use in potentially explosive atmospheres
* (or other equivalent
standard), paragraph 38;
pumps are potential ignition sources and should be located outside the bund – this will also
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avoid damage from fires or spillages in the bund and facilitate access for maintenance (and in
practice the bund should not be considered to be a normal operational area), paragraph 104;
the bund should be liquid tight … and ….the integrity of the bund wall may be put at risk if
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pipework and other equipment are allowed to penetrate it. If it is necessary to pass pipes
through the bund wall, for example to the pump, then the effect on the structural strength
should be assessed. Additional measures may be needed to ensure that the bund wall
remains liquid tight.
187 It is common practice within some parts of the chemical industry to situate ATEX rated
pumps in bunds, for operational or space reasons.
188 Recommendation 11 of the Buncefield MIIB report addresses the connected issue of “the
classification of places within COMAH sites where explosive atmospheres may occur and their
selection of equipment and protective systems (as required by the Dangerous Substances and
Explosive Atmospheres Regulations 2002).
189 The COMAH Containment policy states that: “Bunds shall have no pipework that penetrates
through the bund floor; no pipework that penetrates through the bund walls as far as reasonably
practicable, otherwise it shall be with adequate sealing and support.”
190 Designing and modifying pipe systems to avoid pipe penetrations may be operationally
difficult due to pumps, located outside the bund, requiring flooded suction lines at all tank
inventory levels. Under these circumstances pipeline penetrations will be required.
191 If pipes do not have a continuous fall from the tank to the pump then:
pumps cannot be primed (particularly when stop/starting pumping at low tank levels);
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retention of a pressure differential between tank and serving pump to ensure suction
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throughout the working volume of the tank may be compromised;
lines would have to be drained and cleaned from inside the bund area when changing
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between products.
192 When these activities are carried out on a regular basis then pipes will need to pass through
the bund wall. Where they do, structural effects should be assessed and penetrations should be
designed to be liquid tight and fire resistant.
193 Smaller tanks can be installed at an elevated position and achieve line falls whilst avoiding
pipe penetrations but this is generally not a practical solution for larger tanks (for example with a
volume greater than 100 m
3
).
* Many of the sections of this code have been superseded/withdrawn. The application of the BS EN 60079
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suite of standards is more appropriate and this is also referred to in HSG176. It covers selection of equipment,
area classification, maintenance and inspection etc.