The old Halon system had been functioning since 1973 and consisted of strategically placed Halon cylinders (20 litres) on top of the floating roof tanks. Each contained a glass bulb that would break after a linear heat detection had picked up a heat source. The agent then would then be released in between the secondary and primary seal of the tank roof. Seeing that Halon was considered the most effective way to suppress hydrocarbon fires, the refinery faced a considerable challenge – how to find a system that did not compromise safety in any way?

The oil company which owns the refinery had experienced one or two very serious incidents in the years before 2002, and therefore it had tripled the severity of its safety regime. Another issue that had to be taken into account was that crude oil was becoming increasingly less pure, containing more pollutants with the additional risk of H2S (Hydrogen Sulfide) build up. H2S is an extremely toxic gas produced by the micro organisms that process organic matter and is present in oil barrels and pipelines. All of these factors called for an extremely efficient fire protection system.

Jan Smit (not real name), an engineer involved in the project, explained that the project objective could be summarised in one sentence: “Find an alternative fire detection and protection system for 30 floating roof tanks.”

Smit added that the main requirement was that the rim seal on top of the floating roof tank had to be full of foam within 10 minutes. In this case “full” means a layer of foam up to 10 cm from the edge of the dam, in order to close of the seal of the tank.

It was also specified in the tender that all pipework had to be resistant against firefighting foam solutions, and the heat detection wire by temperature – digital linear detection – set at 138 0C.

The project ended up costing 3.4 million euros, involving three kilometres of foam dam, three kilometres of heat detection cable, 6.7 kilometres of pipe work and 151 foam chambers. Svenska Skum, part of Tyco Fire Suppression and Building Products, was heavily involved in the engineering work and was contracted by Refinery 1 to supply and install the rim seal pourers (AKA over-the-top foam generators), ranging from the smallest being 100 lpm to the largest at 700 lpm capacity. In those days, Skum had only just finalised the design for the Skum OFG50/80, and now this type of monitor is one of the company’s most popular choices for floating roof tank protection. The monitors also have the ability to be closed off, and then foam can be distributed from the rear of the monitor to enable maintenance tests, as it would be highly dangerous to pour foam on a full tank.

In order to test the efficiency of the system the engineering team mounted the Skum rim seal pourers on a single tank, and connected the monitors to fire appliances on pre-determined positions, to see if they could fill the seal to the edge of the tank within the designated time. The test was successful, and this strategy was then applied to all the other tanks on the farm.

One standard that had to be taken into account was NFPA 11a, which outlines the minimum requirements for the installation, design, operation, testing, and maintenance of medium and high expansion foam systems, explained Jan Smit. “This standard also stipulates how water on the roof of a tank should be drained. This is extremely important, because when the load (of water) is unevenly distributed, the balance of the floating roof can be compromised, causing it to capsize. Therefore the foam dam contains holes that drain the water on the roof off the tank. According to NFPA11a regulations the floating roof should be able to withstand a monsoon.”

Two standard vehicle positions were designated for every storage tank. In case of an incident either vehicles or mobile pumps (which work at low pressure of 10 bar) would be connected with the rim seal pourers outside the bund wall. All tanks have two hydrants and the network pressure is sufficient to pump the foam on top of the tanks.

Jan Smit, who was involved in the project said that the installation of three kilometres of foam dam on a floating roof tank was a high risk project in itself, as welding the foam dam on a tank full of product was out of the question. “It was a Herculean job, because the engineering team had to work on top of a huge tank filled with gasoline, and every hole had to be drilled by hand. We had to use water to cool it down, and then seal the holes with rubber for increased protection and leak proofing. At the same time, we had to make the steelplate construction (foam dam) as strong as possible because it could stick out over the tank’s edge, and therefore it had to be able to resist any type of weather. However, up till now so far they have stood the test of time.”

Although Refinery1 is based near a river with brackish water, it uses sweet water from the network for standard firefighting operations. If an incident should occur where there is a need for additional water supply, then the fire service would also have the option of a firefighting boat that could deliver extra water from the river at 6,000 lpm. However, in this case the AFFF ATC 3x3 foam used by Refinery1 would have to be proportioned differently to achieve the most effective extinguishing solution.

In conclusion, Jan Smit, explains that without a biological fire water run off system the refinery would not get permission to operate under Dutch regulations. Seeing as there is additional high-risk industry in the area, Evides (the local water company) has placed installations to process run off in an environmentally friendly manner.

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