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August 2008
Hermetically sealed on the road - Light, high-endurance manhole covers made of polyurethane sandwich composite
Manhole covers from Hermelock nv, based in Tongeren, Belgium, are made of a thick sandwich composite based on the solid polyurethane casting system Baydur® GS from BaySystems. These covers weigh considerably less than the conventional article, but are still strong enough to bear loads of up to 40 metric tons over extended periods of time.
Manhole covers from Hermelock nv, based in Tongeren, Belgium, are the ideal alternative. They are made of a thick sandwich composite based on the solid polyurethane casting system Baydur® GS. These covers weigh considerably less than the conventional article, but are still strong enough to bear loads of up to 40 metric tons over extended periods of time. In addition to roads and parking lots, they are also used in gas stations, industrial sites, sports facilities, garage facilities and driveways. Due to the lightweight sandwich composite and sound-absorbing properties of the polyurethane system, the new covers have already replaced cast iron models in Poland and Australia. Another current area of application is the new high speed train route from Paris via Brussels, Antwerp and Rotterdam to Amsterdam. Hermelock supplied the manhole covers for the Belgian and Dutch train stations.
During the manufacturing process, several layers of glass fiber and plastic mats are laid on top of one another and inserted into a large mold. The mold is then filled with the solid, black polyurethane casting system, and closed. After a curing period of around three minutes, the sandwich composite can be removed from the mold. The layered mats are the key to the cover’s impressive strength. The polyurethane system is extremely flexible and ensures the cover cannot break. It also creates a quite unique size to weight ratio. Hermelock’s specially designed lifter means that workers only have to lift a small portion of the total weight of the HE-800SD model, for example. The material also displays impressive sound-absorbing properties.
The cover is also equipped with a siphon that acts as a seal against odors, while the integrated four-point locking system prevents the cover from being opened by unauthorized persons. Hermelock’s products conform to European standard EN-124 for gully tops and manhole tops for vehicular and pedestrian areas in class D 400 (ductile tops).
These developments enabled Hermelock to benefit from the polyurethane expertise that Bayer MaterialScience has honed over decades as the world’s most experienced supplier to customers in the polyurethane industry. BaySystems®, the umbrella brand for the global polyurethane systems operations of Bayer MaterialScience, has grown out of this expertise and the company’s close cooperation with its customers.
About Bayer MaterialScience:
With 2007 sales of EUR 10.4 billion, Bayer MaterialScience is among the world’s largest polymer companies. Business activities are focused on the manufacture of high-tech polymer materials and the development of innovative solutions for products used in many areas of daily life. The main segments served are the automotive, electrical and electronics, construction, and sports and leisure industries. Bayer MaterialScience has 30 production sites around the globe and employed approximately 15,400 people at the end of 2007. Bayer MaterialScience is a Bayer Group company.
More information can be found under www.bayermaterialscience.com and www.hermelock.be.
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