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Simon Storage Ltd – Immingham East Terminal
Gasoline Import – Layers of Protection Analysis
P & I Design Ltd
DOCUMENT NO: SI057001_RPT
2 Reed Street, Thornaby, UK, TS17 7AF
ISSUE: G DATE: 29.06.12
Tel: + 44 (0)1642 617444
PAGE 6 OF 34
Fax: + 44 (0)1642 616447
www.pidesign.co.uk2.2
Summary of LOPA Study
The results of the study are summarised below:
Scenario 1
- Overfill of gasoline tank during import from a ship leading to a potential open
vapour cloud explosion causing up to 3 on-site fatalities and up to 6 off-site fatalities.
Risk Tolerance Criteria
=
1.0 x 10
-6
per year
Frequency of Mitigated Consequence
=
7.58 x 10
-7
per year
The risk tolerance criteria is within the Broadly Acceptable region for up to 10 fatalities
(Table 2 - Tolerable Risk Criteria). The frequency of Mitigated Consequence with a mid-
range SIL 2 SIS is well within the “Broadly Acceptable” region.
Scenario 2
- Overfill of gasoline tank during import from a ship leading to a potential flash
fire causing up to 1 on-site fatality and no off-site fatalities.
Risk Tolerance Criteria
=
1.0 x 10
-5
per year
Frequency of Mitigated Consequence
=
8.81 x 10
-7
per year
The risk tolerance criteria is within the Broadly Acceptable region for up to 1 fatality
(Table 2 - Tolerable Risk Criteria). The frequency of Mitigated Consequence with a mid-
range SIL 2 SIS is well within the “Broadly Acceptable” region.
Scenario 3
- Overfill of gasoline tank during import from a ship leading to a potential open
vapour cloud explosion and a release to the River Humber corresponding to a potential
short-term major environmental consequence to the River Humber which could constitute
a threat to the environment. (Consistent with Table 4 - Environmental Tolerable Risk
Frequency).
Risk Tolerance Criteria
=
1.0 x 10
-6
per year
Frequency of Mitigated Consequence
=
6.06 x 10
-7
per year
The risk tolerance criteria is within the Acceptable region for a severe environmental
consequence (Table 4 - Environmental Tolerable Risk Frequency). The frequency of
Mitigated Consequence with a mid-range SIL 2 SIS is well within the “Broadly
Acceptable” region.
The above were achieved with the following:
A mid-range SIL2 protection layer which would close individual tank-side
pipeline fail-safe actuated valves on initiation of that tank’s high high level
switch. This protection layer has been installed and commissioned and full SIS
documentation is available. The actual credit available from the SIS is calculated
as: 2.5 x 10
-3
. See SIS Design Report SI277001_RPT. The protection layer is
auditable via the SIS maintenance and testing records.