Fire protection of above-ground tanks classified under section 1436, 4330, 4331, 4722, 4734, 4742, 4743, 4744, 4746, 4747 or 4748, or, for crude petroleum, section 4510 or 4511 of the legislation governing facilities classified for environmental protection
The purpose of the 3 October 2010 Order is to legislate on and protect above-ground storage tanks containing hydrocarbons or alcohols within a facility classified for environmental protection (ICPE) subject to authorisation. Operators have until 31 December 2018 to comply with the requirements of the Order. Here we shall identify the authorities’ expectations described through article 43 of the Order which aims to protect tanks against fire.
The Order requires industrial companies to implement a strategy to control a fire in a storage tank, secondary containment area or mobile flammable liquid containers. By controlling these scenarios, fire will be prevented from spreading by a domino effect to the entire site.
On the subject of fire control of storage tanks, industrial companies must adopt a stance with regard to their ability to act autonomously in the event of an outbreak of fire. Operators are “autonomous” where their strategy does not call on public fire and rescue services. Instead, they have their own firefighting means and/or can draw up mutual assistance protocols or private agreements. Note that the Prefecture is entitled to refuse that a site not have autonomous fire control arrangements.
A 3% or 6% foam solution using an Aqueous Film-Forming Foam (AFFF) concentrate is recommended for fighting flammable liquid fires.
The 3 October 2010 Order has two annexes relating to fire control. They indicate the extinguishing and cooling application rates and the volumes of water and foam concentrate to be provided on site. Operators apply the provisions of Annex V in the scope of autonomous fire control or Annex VI for non-autonomous fire control. The application rates to be provided in the case of non-autonomy are considerably higher than for autonomous fire control.
As far as autonomy is concerned, the operator has two possibilities:
With fixed systems, experimental application rates can be adopted instead of flat rates for secondary containment fires. While these fires are often the worst-case scenarios, the volumes of water and foam concentrate to be stored in situ can be optimised by using experimental rates. The conditions for using these rates are subject to the use of the foam concentrates listed as being particularly efficient by the fire safety training and assessment entity, GESIP. With these foam concentrates, it is possible to cut back from a flat application rate of 4 L/min/m² with a mild application to a rate of 2.5 L/min/m². The implementation of this rate is subject to following the recommendations of GESIP Guidelines 99/02 and 2012/02. The volume of water and foam concentrate must allow at least 20 minutes’ operation.
A fixed firefighting system must be equipped with a suitable diesel-driven pump unit delivering sufficient flow rate/pressure to feed all the activated equipment. To guarantee system reliability, it must have a second pump unit that will kick in should the first pump unit fail. The supply system between the pump room and the storage tanks must be a gridiron system that can be shut off.
The storage tanks and secondary containment areas must be equipped with a fire detection system to ensure adequate site protection. The detection equipment is connected to a fire control unit or a programmable automatic controller to relay information or even control the systems remotely.
It is possible to interlock the activation of the fire protection means with detection. However, this type of system exposes storage facilities to false alarms which would trigger the firefighting means accidentally. This is why semi-automatic activation is a good compromise. In this case, the operator confirms activation of the fire extinguishing scenario after verification.
To trigger a scenario from a controller, control valves must be installed upstream of the fire protection equipment (generators and foam boxes, spray heads, etc.). A control valve is an assembly that can be activated remotely and designed to allow water to flow through to a fire system. The control valve triggers the interlocked fire protection equipment. It separates the gridiron and wet piping system feeding the entire fire protection system from the dry, single-leg systems designed to feed specific equipment.
Given the requirements of the 3 October 2010 Order, substantial investment must be assigned to fire protection. Considerable thought must be given to the means installed, which must be optimised to ensure effective protection suitable for the site. Legal obligations in terms of fire control must be turned to the advantage of industrial companies to ensure the sustainability of the facility.