Contaminated fuel stories seem to hit the headlines on a pretty regular basis on regional websites. The latest, concerning a BP site, even made the nationals including The Sun. A BP site in Rayleigh, Essex, was found to have a ‘potentially contaminated tank’ which was being investigated.
The oil giant told The Sun that the tank in question had been isolated and the site was fully operational. Of course, it’s not just BP which is affected by such problems, but when these things do occur it can lead to reputational damage as well as hefty costs.
Edward Wheeler, group managing director, Eurotank Service Group, says that while he couldn’t comment on any individual case without being involved in the investigation, contaminated fuel is often the result of water mixing with petrol causing a process called phase separation.
“This occurs when the water content of the fuel’s alcohol component becomes saturated to a point where the alcohol has a specific gravity closer to water than petrol. Becoming heavier it will ‘phase separate’ and drop out of the petrol and sink to the bottom of the tank. The higher the alcohol content, the higher the level of water required for this process to occur so E10 has the capacity to absorb more water before phase separating than E5, for example.
“Unfortunately, the water and alcohol mix that builds up in the bottom of the tank does not have the same specific gravity as pure water, so very often the water float will not be fully buoyant and not go into alarm.”
Wheeler explains that there are several ways groundwater can get into fuel stored at petrol stations, ranging from a tank shell breach in single-skin tanks, an inner skin breach in a double-skin tank, or from the tank manway access chamber via a failed gasket, joint or loose fitting.
“Water can also enter the tanker delivery pipework, due to the cap not being correctly replaced, a leak on any of the underground pipework connected to the tank, or a ‘wet’ delivery where fuel is delivered to the site with a high water or already phase separated content.”
Although phase separation is rare, Wheeler says it is the potential consequence of a lack of housekeeping. Housekeeping tasks that can help to prevent phase separation occurring include:
• Keeping tank manway access chambers and underground chambers containing fill points free of water
• Checking and replacing seals on tanker fill point caps if underground or above ground in areas likely to flood. This is good practice to ensure vapour doesn’t leak out as well.
• Periodic internal tank inspections and repairs of areas of corrosion
• Inspection and changing of gaskets providing primary containment such as tank lid gaskets.
“Seals and gaskets are of critical importance in all retail petrol storage systems as they prevent both fuel from leaking out and water leaking in,” says Wheeler.
Material compatibility challenges
Wheeler says his company has seen many problems caused by using seals and gasket materials that weren’t suitable for modern fuel blends. “Tens, sometimes over a hundred thousand pounds per incident of cost to the retailer from a single seal failure, which causes vehicle breakdowns and damaged fuel product that has to be taken away for recycling.
“Don’t leave this to chance when you are in the design phase of a new petrol station or planning a refurbishment. You need to give as much attention to material compatibility as you do for how your shop is fitted because it could come back to bite you in the future.
“In all the incidents we’ve dealt with over the years, the seals and gaskets were meant to be compatible with the fuel in the tank but they weren’t, so make sure you challenge the architect/contractor on what equipment is going to be used and question its compatibility. For petrol, the highest fluro elastomer material like ‘Viton’ is necessary. It’s very expensive in comparison to lower ‘fuel proof’ specifications so there is a significant commercial pressure not to use it, but you need it to protect yourself from failure.”
Tank upgrades
Eurotank Environmental carried out a variety of tank upgrades last year, including the final sites in a six-year project for one customer. The project has seen Eurotank install its flagship tank-within-a-tank Lifeliner tank lining system in just under 350 tanks across 129 petrol stations.
Lifeliner involves a new resin composite tank being built inside an existing tank, monitored by a class 1 pressure monitoring system as standard, and comes with a 30-year warranty. Lifeliner is also available in a single-skin version, which comes with a 20-year warranty. With the existing steel tank as a mould, three layers of hand-laid fibreglass and resin create a new single composite tank.
This year, Eurotank is also able to offer lower-volume sites a lower cost version of Lifeliner called Lifeliner Lite, which is a specially adapted system that is 30% cheaper than the full Lifeliner double-skin lining and is available in both double and single skin.
Other linings installed by Eurotank last year include Fastliner, which is a bladder liner that can be installed by going inside the tank or completely remotely.
One of the main benefits of Eurotank’s tank lining offer is that even Lifeliner can be installed on live sites so that retailers can continue trading throughout.
Jack Aplin, group sales director, says: “We keep disruption to retailers and their customers to an absolute minimum by using a container craned into position over the top of the tank manways using our lorry-mounted crane.”
Tank integrity
Eurotank is seeing increasing numbers of its retail customers with single-skin tanks thinking about the integrity of those tanks, and the environmental impact they could have in the future.
Aplin says: “In a lot of cases retailers don’t know the age of their tanks and have never had any kind of condition report completed on them. This causes a dilemma for the site owner to decide what action needs to be taken and how much investment is required.
“A lot of owners believe the only options are to re-line the tanks or to simply do nothing. However, we believe the best option is to first find out the condition of your single skin tank, so an informed and calculated decision can be made.”
Aplin explains that Eurotank engineers often find that once tanks are emptied, and years of compacted sediment and rust are removed, micro leaks are identified.
“We can reinforce these areas with GRP doing localised repairs and effectively stopping a minor issue before it becomes a major issue. Our engineers inspect the steel shell in fine detail, taking notice of the depth of pitting corrosions. Areas that are considered ‘deep’ can be reinforced with GRP repairs that will effectively stop the corrosion in the area completely.”
He says steel tanks generally fail due to spot corrosion. “Failed tanks can nearly always be repaired without the need to complete a full re-line. The main benefits of our tank re-tightening service are that failed tanks can be put back into use very quickly, the cost is low in comparison to full replacement or re-lining, and our experience is that re-tightened tanks have not failed again.”
Aplin says this re-tightening process has multiple benefits: the tank is fully cleaned; the thickness of the tank shell is measured and compared to its original thickness; internal corrosion can be inspected and pitting areas risk-assessed; localised fibreglass patches can be applied in the tank to upgrade risk points; and tank lids and fittings are cleaned as part of the lid removal and replacement.
“The re-tightening process can be even more beneficial to operators that have multiple sites with single skin tanks as the re-tightening process costs significantly less than tank lining. Once the assessment work has been completed, companies can budget and make real plans for spending money on the right tanks at the right time.”
National assistance
Petroassist UK says its in-house teams have installed thousands of miles of pipework across the UK fuel retailing industry, as well as fuel pumps and tank gauge systems.
The company has a complete installation service providing customers with a ‘one stop shop’ for all forecourt development requirements including pipework, electrical installation, civils works and project management.
Bailey Carter, dealer sales manager – UK & Ireland at Petroassist UK, says these pipework installations are the foundation to any site and the Petroassist team has an extensive experience of working with major groups and independent retailers across England, Scotland, and Wales.
“We supply state of the art equipment but, more importantly, it is the support and maintenance of the equipment where we really stand out from the crowd.”
