European Petrol Stations Will Glass Reinforced Plastic (GRP) Storage Tanks soon become a piece of History?
by Jamie Thompson
The oil industry has in the recent years of its history had a choice of materials to construct the storage vessels at its petrol filling stations. The traditional non corrosion resistant steel storage tanks used in the early 1900’s have always had a problem in that they will rust and eventually leak. Those resultant leaks and clean up have in the latter years provided environmentalists and safety authorities with a reason to criticise the industry for failing to take proper care of its products. One result of this criticism was the birth of the Glass Fibre Tank industry in the 1960’s, as one of the great virtues of GRP is that it would not rust! The industry developed in the US and at that time successfully challenged the steel tank industry on their right to sole supply stations in the US. Eventually but much later this industry moved to Europe. The first GRP tanks to be installed in Europe at petrol stations were in the UK and Norway in the early 1970’s and it was Esso that pioneered this work under a UK engineer Keith Sherwood but despite the relative success in marketing this concept in the US, the tanks did not start to be installed in any great numbers in the UK until the end of the 1980’s.
At that time Ferranti Resin Ltd who had a factory in Peterlee in Co Durham were the main supplier and after a successful marketing campaign they gradually won around some major clients who, until that time, were all using unprotected single wall steel tanks. The engineering staff at Mobil Oil, headed by an American Mike Pearce, was keen to see the successful transfer of their GRP Tank policy from the US to Europe. In addition other Oil companies were looking at having trial sites and eventually BP became the second major in Europe committed to using GRP tanks as a company policy. In Europe an organisation called EPACT was set up to promote the use of composites in the oil industry, with GRP tank and pipe manufacturers participated in spreading the message that GRP was the answer to the oil industries problem. In addition European standards on both single and double wall tanks for GRP tanks have been written for the industry. This organisation was disbanded around 10 years ago.
In the UK around two thousand GRP petrol tanks were made over a ten-year period by Ferranti (later to become Fibre Reinforced Products Ltd) who made under the Owens Corning licence, Klargester making under the Xerxes licence Two smaller manufacturers with their own design, Cambrian Plastics and Balmoral Tanks. In Europe there were also tank manufacturers in Norway, Holland, Spain, France and Italy.
What has gone wrong for the European GRP Tank Industry? In some countries in Europe the introduction of GRP tanks has not succeeded, Germany being a prime example where no one would even try an installation, some other countries have tried a few installations but with no successful follow up. In Norway where GRP had a foothold some oil companies changed policy and removed GRP tanks. In Holland a few installations were put in but there was no successful follow up. The main reason for the failure of GRP sales was that the European steel tank manufacturers have responded to the challenge on their markets in a similar way to their US colleagues.
Tank Rupture due to poor quality control.
The traditional steel tank was improved by offering technology far better than its rival. Double wall tanks with active built in leak detection Improved and long lasting coatings preventing corrosion A European standard was written and accepted across Europe. In addition some failures of a few new GRP installations during and after installation blamed on quality issues caused the industry to use the phrase ‘steel tanks may leak but fibreglass tanks empty’: Following one of these spectacular failures BP decided to reverse its policy and installed one of the first double wall steel tanks manufactured to the new standards. This left just Mobil Oil and Safeway as retail users in the UK of the GRP storage tank. The failure of a series of double wall GRP tanks in five motorway service areas in the UK blamed on design faults during 1990’s must have started doubts in the minds of those engineers involved, however the Mobil policy changed to steel once the BP/Mobil marketing agreement was put into place and Safeway now use steel tanks. Perhaps the most disturbing news for the GRP tank industry was confirmed recently by sources in BP, that a decision has been taken to replace the entire stock of existing GRP tanks with double wall steel. These will be from stations formerly owned by Mobil Oil.
Cracking of double wall tank after four years of use. Sources confirmed that in the UK around 60 tanks have evidence of some degradation and fibreglass strands have been found in product. These tanks would be replaced soon. In addition the remaining 400 GRP tanks in service with the company will be replaced as the policy is enforced. The softening of older GRP tanks by some of the modern fuels has been looked on as a problem in the USA, but the industry has tended to replace tanks on a more regular basis than in Europe. Steel is still the favourite of the majority of tank installers in the USA. The latest figures from Underwriters Laboratories has confirmed that more steel underground tanks were installed in 1999 in the US with around 60% of the total leaving GRP tanks around 40% of the market.
Repairs
necessary on tanks in use after failure.
As I was one of those around during the “conception” of GRP tanks in the 1970’s, and their “re-birth’ in the 1980’s is 2000 the start of their demise?
It is probably too early to say they are gone for good, but certainly the current lack of confidence in the GRP tank for storing petrol in Europe will be a hard one for the industry to recover from.
I also believe that those using tanks to store petrol will need to look at the risks of a sudden failure as some may be installed in high risk situations, there are around 150 of these tanks installed in the Greater London area alone. Some good news from an engineer responsible for the removal, “At least they are a lot easier to remove and dispose of than concrete surrounded steel tanks!”
2001-07-31
ABOVE GROUND STORAGE TANKS Wayne Geyer, Steel Tank Institute
Much of the Bulletin has centered on the subject of Underground Storage Tanks. However, in the United States, over the past ten years, a significant trend in the storage of hazardous and combustible liquids has been occurring - aboveground storage. Aboveground storage tanks (ASTs) systems have been the choice at governmental facilities, military bases, schools, hospitals, private fleet fueling facilities, and for chemical/industrial uses. The ASTs being referred to, are not those clusters of vertical tanks often seen at,bulk storage facilities, isolated far away from buildings and human activity. Rather, today’s common AST applications are one or two horizontal tanks placed within 15 or 25 feet of important buildings, property lines or public ways. While many of these horizontal ASTs are cylindrical, we are also seeing more rectangular configurations. The flat tops of rectangular tanks provide more flexibility in locating the numerous fittings and components required for a safe and proper operations. It also makes it easy to maintain these components and to access the fill opening, because the awkwardness of climbing ladders and balancing on catwalks is alleviated. Most of these tanks are small, 4000-gallon capacity or less. This is significantly smaller than the typical 10,000 12,000 gallon underground storage tank installed at a retail service station.
STI statistics also show that Class combustible liquids (diesel fuel, et al) to be the most commonly stored liquids - accounting for nearly two-thirds of the AST applications. The least common AST application: retail service stations, which account for less than 5% of AST purchases from STI Members.
However, AST storage of motor vehicle fuel private fueling facilities has without a doubt, been the most significant new trend. Prior to 1992, the US fire codes either restricted or prevented this type of usage. Back in the sixties and early seventies, several catastrophic fires occurred which prompted codes to eliminate or severely restrict such usage. Also, tanks were occasionally overfilled, increasing the likelihood of a surrounding pool fire. If tanks were not properly equipped with emergency vents, the flammable liquid quickly vaporizes inside the tank during a fire, leading to overpressurization. Because these are tanks designed for atmospheric pressure only, excessive pressure can cause the tank heads to ejaculate outward, like a missile.
Nevertheless, in the early nineties, tank owners began installing more aboveground tanks, even with the code limitation. This led some states to override fire codes by legislatively allowing ASTs at fueling facilities, balancing the needs of both the tank owners and environmentalists.
Tank owners sought alternatives to underground tank storage. Media attention focused on LUST, release detection, tank testing, and expensive soil and groundwater clean-ups efforts. Aboveground storage provided an attractive alternative. Tank owners could visually examine their storage system for releases. This was the wake-up call to the fire codes, as the codes began a quest to emulate the underground storage of flammable and combustible liquids for aboveground installations. The National Fire Protection Association Automotive and Marine Service Station Committee modified NFPA 30A with a Tentative Interim Amendment in 1992. The TIA provided code language for the safe installation of ASTs in a concrete vault or room. Each vault enabled detection of liquids and vapors, allowed personnel access to physically inspect the tank walls, and provided means to remove water and flammable liquids. For more hazardous Class I liquid (gasoline) storage, the code further required a ventilation system within the vault. The other dominant fire code in the United States took a different approach. The Uniform Fire Code already permitted small aboveground tanks in special enclosures, with 6” thick concrete walls, on an exception basis inside buildings. Why not allow this type of enclosure outside, where the risks were reduced? So the UFC Code developed performance based code language to allow aboveground tanks that emulated the safe environment of an underground tank. If a tank can be built with a great insulator similar to soil, then it could be used aboveground too. This was the birth of the protected tank, a tank with both secondary containment and insulation to protect the tank during a two-hour 2000degree Fahrenheit pool fire. By 1993, both the Uniform Fire Code and NFPA 30A had expanded or created means for aboveground storage of motorized fuels, in capacities up to 10,000 or 12,000 gallons. The fire protected tanks could be installed closer to a building than the traditional UL 142 tank. The codes have a number of requirements designed to prevent releases from ASTs. Secondary containment is one consideration. However, since fire prevention is best addressed by simply eliminating chance of a release, preventing overfills during deliveries was a high code priority. Obviously this concept is not much different from the philosophy of preventing releases with underground storage tank systems. The codes generally require three controls: 1) a gauge on the tank, 2) an audio and/or visual high level alarm, and 3) an automatic shutoff device. The codes also require anti-syphon devices, openings only at the top of the tank, thermal expansion relief devices, and emergency venting of the primary tank and all secondary containment areas. As stated earlier, the emergency vent is the most important device should a fire
occur, regardless of whether the tank is a fire-protected tank or not. Tank owners must make sure that both emergency and normal vent are operable and maintained - always. Along with the code changes during this time, fabrication standard development also experienced significant activity. Underwriters Laboratories increased the length of its UL 142 standard covering storage of flammable liquids in aboveground tanks by two or threefold. New language to covet secondary containment tanks, steel diked tanks, and rectangular tanks was added. UL also introduced a new standard for Insulated Tanks in December 1994. The standard covered two-hour fire testing of both UFC mandated “protected tanks” and NFPA optioned “fire resistant tanks.” O n December 30, 1997, UL released the Second Edition of UL 2085 for protected tanks only. Insulated tanks come in various forms, but there are presently three most common designs built today. One design places the insulation between two walls of steel. The second design places a steel tank within a concrete encasement. The third design places a plastic membrane over the steel tank and encases the entire assembly in concrete. The most recent development came in October 1997, when UL provided its first two listings to a new UL standard - UL 2244. This covers complete factory assembled AST systems. In other words, all important core components of a tank used for motor vehicle fueling, aviation fueling, generator tanks, etc. are evaluated by UL at the factory prior to shipment. The goal is to remove the concerns of authorities having jurisdiction (AHJs) for missing emergency vents and other accessories that prevent releases and system failure during fires. After all, what good is a two-hour fire rated tank if important components are not attached? Steel Tank Institute also developed several important new AST standards over the past several years: the F911 steel dike AST, the F921 double wall AST, and the F951 protected aboveground secondary containment tank (given the name “Fireguard). Before the turn of the century, STI statistics showed a tremendous growth rate in F921 and Fireguard tank installations. Over 2500 protected Fireguard tanks were being built annually. The inclusion of secondary containment for AST has justifiably received a great deal of attention lately. In 1991, EPA proposed an amendment to the SPCC (Spill Prevention Control Countermeasure Plan) requirements for ASTs suggesting that secondary containment be impermeable for 72 hours. This fact, coupled with the fire code activity, has created a tremendous demand for aboveground tanks with built-in secondary containment. This can be in the form of integral dikes, double wall construction or insulated tanks with secondary containment. The NFPA Flammable and Combustible
Liquid Code, NFPA 30, allows any tank, 12,000 gallons and under, with overfill prevention devices and emergency venting devices, to be a secondarily contained tank, as an alternative to a traditional dike. Today, nearly one-third to one-half of STI Members’ ASTs are being built with secondary containment. Compare this to ten years ago when that statistic was closer to 0-5%. Finally, some basic installation requirements should be mentioned. Tanks must be installed on a firm foundation. In areas prone to flooding or earthquakes, tanks may require further anchoring (or seismic considerations) in accordance with local fire or building codes. When tanks arrive at the site, the NFPA 30 code requires both primary and secondary containment tanks be air tested to assure that tank integrity remained throughout shipment. Piping considerations are another big factor. Many of these AST motor vehicle fueling facilities do not require underground piping, as the dispensers are mounted directly atop or to the side of the tank. While eliminating another cause of release common to old underground storage tank systems, aboveground piping must be
protected against potential damage by vehicular impact at fueling facilities. Aboveground tanks do have their pitfalls, however. More maintenance is required to keep the tank aesthetically acceptable, such as painting steel or patching cracks in the concrete. Condensation will be a bigger factor in aboveground storage tanks. The operator needs to check for water at the tank bottom on a monthly basis and all water should be removed.
Also, spill prevention plans for aboveground storage tank systems larger than 660 gallons, which are located such that a release into a navigable waterway can potentially occur, are required. Also, the tanks must be protected from vehicle impact. Extra security measures, such as a fence enclosure, are necessary to guard against vandalism. Overall though, the non-retail sector of tank system operators who store motor vehicle fuels has chosen ASTs over USTs because of convenience, cost, and the ability to see the tank at all times.