StocExpo 2012
Ross Coulman
15th March 2012
History has told us multiple events occur
Multiple Tanks and Bund / Dykes
=
Natural escalation
Worse case is the Bund/Dyke
Not your largest tank
not enough foam
not enough foam
430k for 65 minute application
not enough foam
559k for 85 minute application
not enough capacity
INSERT Dyke Volume Calculation
BUND Holds XXXXX litres
not enough capacity
INSERT Dyke Volume Calculation
Fire water alone is 11,272,300 litres
not enough capacity
INSERT Dyke Volume Calculation
Fire water plus rainwater@ xx% =
XX,XXX,XXX litres
not enough capacity
INSERT Dyke Volume Calculation
Fire water plus rainwater@ xx% =
XX,XXX,XXX litres
PLUS Product 100% largest tank, 10% of
all others = XX,XXX,XXX litres
IP 19
HSG 176
CIRA 598
EN 1992
BS EN 14015
vertical, cylindrical, non-refrigerated, above-ground storage
tanks typically
designed to standards BS 2654,3 BS EN 14015,4 API 620,5
API 6506
Single case pre-plan methodology
Boilover potential provides escalation – potential to create
lots of multiple events
Single case pre-plan methodology
Pessimism is good – saying singles case is acceptable due
to frequency level is naïve
Single case pre-plan methodology
Have you taken the shared learning and applied it post
buncefield?
Single case pre-plan methodology
Negatives
History has told us multiple events occur (Buncefield) –
Multiple Tanks natural escalation
Worse case is the Dyke not your largest tank –
shortcomings;
- not enough foam
- not enough water
- not enough manpower
- not enough …..
Boilover potential provides escalation – potential to create
lots of multiple events
Single case pre-plan methodology
The factors to be taken into account when sizing bunds to deal with multi-tank failure scenarios and fire water management, plus the
capacity for remote [tertiary] containment systems, are:
Primary capacity - 100% of primary capacity. Consider the possible failure modes and where appropriate, include the capacity of all primary
tanks in multi-tank installations, incidence of multiple tanks in one bund and where tanks are hydraulically linked in which case they should
be treated as if they were a single tank.
Rainfall - subject to operational procedures, in order to calculate the volume to be contained, allow for a 10 year return, 8 days rainfall prior
to the incident, and a 10 year return, 24 hour rainfall, plus an allowance for rain falling directly on to remote containment and areas of the
site draining into it, immediately after the incident. The post-incident component and the allowance for dynamic effects (see e) are not
additive.
Fire fighting and cooling water - Allow for the volume of extinguishing and cooling water delivered through fixed and non-fixed installations
based on BS5306, VCI, CEA, ICI and Institute of Petroleum methodologies, with appropriate adjustments in the light of the particular
circumstances.
Consultation with the regulators and the fire service is essential.
Foam - Allow a freeboard of not less than 100 mm.
Dynamic effects - this is to allow for the initial surge of liquid and for wind-blown waves.
In the absence of detailed analysis, allow 250mm (750 mm for earth walled bunds).
Health and Safety Executive (UK) recommendations on multi tank
and bund/dyke modelling post Buncefield disaster
Tailored to risk, not Prescriptive
Swiss Cheese Model
People – Process – Plant
People are the weakest link
Identify Vulnerability
Compare and contrast single source and multi-source incident
scenarios
No excuses – it’s easy to model multi-source
Q&A