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Safety and environmental standards for fuel storage sites
Final report
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109 For tanks within scope, the expectation is that primary and secondary criteria in HSG244
would not normally eliminate the need for a ROSOV to the outlet pipe and as such a case-specific
assessment as set out in Appendix 1 of HSG244 should be undertaken. For existing sites, the
case-specific assessment should fully consider:
whether fitting a ROSOV, where none is currently provided, is reasonably practicable;
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where a ROV is provided but it does not normally fail safe, whether upgrading to a fail-safe
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valve is reasonably practicable; and
where an existing ROV does not fail safe, and it is not considered reasonably practicable
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to upgrade it, what additional measures should be provided to protect against failure, eg
providing fire protection to the cabling and increasing the frequency of inspection and testing
of the valve and associated cabling and energy supply.
Configuration
110 Bulk storage tanks can have their import and export lines arranged in a variety of configurations.
These have a bearing on the necessary arrangements for isolating the tank inlets/outlets. Some
tanks will have separate, dedicated import and export lines. Within this group, some will fill from the
top and export from the base; some will both fill and export from either the top or the base. Others
will have a single common import/export line, commonly connected at the base of the tank.
Dedicated import line
111 Tanks with dedicated import lines, whether these enter at the top or the base can be
protected against backflow from the tank by the provision of non-return valves. Lines that enter
at the top of the tank and deliver via a dip leg may in some cases be adequately protected by the
provision of a siphon break to prevent the tank contents flowing back out via the feed line.
112 The provision of either or both of these features may affect the conclusion of any assessment
of the need to provide a ROSOV for the purpose of emergency isolation of the tank against loss of
the contents. These factors need to be considered when determining the appropriate failure mode
for the valve or whether motorised ‘fail in place’-type valves are acceptable.
Dedicated export line
113 Dedicated export lines on bulk tanks containing petrol should ideally be fitted with fire-safe,
fail-closed ROSOVs; this would be the minimum expectation for a new tank installation. For existing
installations, the need to provide ROSOVs retrospectively should be subject to an assessment
according to the principles in HSG244. This assessment will need to include consideration of an
individual having to enter a hazardous location to manually operate a valve for emergency isolation.
Common import/export lines
114 These lines cannot be provided with a non-return valve and it appears most appropriate to
assess the ROSOV requirement, including the failure mode of the valve, based on the export function.
MIIB Recommendation 6
The sector should put in place arrangements to ensure the receiving site (as opposed to the
transmitting location) has ultimate control of tank filling. The receiving site should be able to safely
terminate or divert a transfer (to prevent loss of containment or other dangerous conditions) without
depending on the actions of a remote third party, or on the availability of communications to a
remote location. These arrangements will need to consider upstream implications for the pipeline
network, other facilities on the system and refineries.
MIIB Recommendation 7
In conjunction with Recommendation 6, the sector and the Competent Authority should undertake
a review of the adequacy of existing safety arrangements, including communications, employed
by those responsible for pipeline transfers of fuel. This work should be aligned with implementing
Recommendations 19 and 20 on high reliability organisations to ensure major hazard risk controls
address the management of critical organisational interfaces.