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Fuels

Opinion: Preventing Fuel-Storage Contamination

From containment systems to manhole covers, newer materials stop water intrusion

CINCINNATI -- Water’s innate ability to work its way into every stray crack and crevice, oftentimes with harmful effects, can make life extremely difficult. Just ask any operator of a retail-fueling operation. Water intrusion is a constant threat to underground storage tanks (USTs) and, if unchecked, can cause great harm to the fueling system. In addition, if water can get in, it usually means fuel can get out.

As ethanol-blended gasoline has become standard, the potential for “phase separation” has grown. Phase separation occurs when enough water contaminates the gasoline to cause the ethanol to attach itself to the water molecules, leaving two distinct layers of fuel in the storage tank: a gasoline-only layer at the top and an ethanol/water cocktail along the bottom. This phase separation of the gasoline/ethanol mix lowers the octane number of the fuel and may cause knocking in the vehicle’s engine. The engine will not run at all on the ethanol/water mixture.

Because of the potential for phase separation, motor fuels containing ethanol must not be exposed to water during its distribution or use. This makes housekeeping at the service station very important. The key is eliminating the chance of harmful water intrusion at the source—the UST’s sump and spill-containment areas, or the spot at the ground surface where the tank receives fuel deliveries.

A noteworthy, recent advancement in this area has been the creation and refinement of the multiport containment system. The new-age multiport system has two composite spill-containment covers located on a larger composite cover. The smaller covers can be removed in seconds, which allows easy access and quick connection of hoses to fuel-delivery and vapor-recovery piping.

Advanced multiports were needed because water intrusion was still a significant issue with first-generation steel designs. Today, multiport systems that are constructed of highly engineered glass-reinforced plastic (GRP) composites possess the capability to keep sumps and spill-containment areas dry, which helps prevent water intrusion into the fueling system and eliminate concerns that retailers will be selling contaminated fuel.

Manhole Application

The growing availability and use of composite multiport systems continues an industrywide trend toward forecourt fuel-storage and delivery components and systems constructed of GRP composites. Manhole covers, for example, appear to be simple and straightforward components; however, they are anything but. In fact, considerations over health and safety, aesthetics, construction materials and the atmospheric conditions in which manhole covers are used have guided their evolution over the years.

Traditional access covers were usually made of metal, but steel covers have a number of drawbacks. They are heavy, which makes them hard to move. They are high-maintenance and can rust and corrode, necessitating the need for repainting. Over time, metal lids can deflect and develop a bowl shape. And steel covers become very slippery when wet or covered with snow and ice.

Recognizing these shortcomings, there is growing acceptance of access covers that are constructed of GRP composites. These covers weigh only one-third that of their steel counterparts, while maintaining a strength-to-weight ratio that allows them to absorb the abuse that occurs on the forecourt. Also, composite covers don’t corrode when exposed to the elements and have a low coefficient of expansion. Therefore, changing weather conditions do not affect their shape, which is a critical consideration for areas of the country that experience both the stifling heat of summer and the numbing cold of winter.

In addition, composite covers can be manufactured in any color with no need for additional painting or upkeep. Nonslip materials and tread patterns can also be molded into the cover to reduce slipping by people or the skidding of vehicle tires.

Today, almost 90% of large-diameter of covers 36 inches and more on the forecourt are made of composite materials, with more than half of all other access covers constructed of composites. While many smaller access covers are still constructed of steel, the benefits that are inherent in the design and operation of the next-generation multiport systems indicate that composites will soon become the go-to technology for their construction, too.

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