Damaged covers may be found in just about every village. This is also the number of covers to be replaced. The most common situations: damage to the support (insert), damaged cover or frame ring, but also damage to the asphalt or concrete around the frame itself. Repair cost are usually high, and include: a road block, tearing-up of the damaged cover and dismantling, repair works on the shaft, cover replacement, placing of concrete around it, placing of asphalt, and removal of rubble. In order to replace the damaged cover, the following is required: a workgroup consisting of at least 3 people, a suitable vehicle (half-truck), signalling equipment, concrete, asphalt, adequate tools (incl. a pneumatic hammer). On roads with frequent / heavy traffic the replacing is needed almost each year. In all branches of metal-casting industry, the traditional grey cast iron is gradually giving way to the ductile cast iron. This is especially due to the properties of the ductile cast iron such as elasticity, 30% less weight etc. New applications of ductile iron technologies enable manufacturing of high-grade products which are resistant to dynamic forces which, in turn, prolongs their service-life.
Saint-Gobain PAM has been successfully manufacturing covers and grates for more than 30 years. For example: in the last decade more than 1.200.000 PAMREX covers have been installed. Of those only a negligible number of them have been replaced (a few dozen pieces). In the long-term, the use of these products is justified, since the maintenance cost is minimal.
Light-weight and easy to use
Products made of ductile cast iron are about 30% lighter than the comparable covers made of grey cast iron. Hence, the maintenance and use of these covers is much easier. The hinge provides for a safe and trouble-free operation, and requires up to 50% less force when opening.
Saint-Gobain PAM covers are in most cases equipped with anti-noise inserts made from resistant and durable tested materials (PE, composites, elastomer material). "The silent" covers have proven themselves many times as an excellent solution, including on the roads with heavy traffic. In addition to preventing noise, these inserts absorb the dynamic loads (dampening effect), thereby prolonging the service life of the cover.
Stable structure, smart design and ductile iron ensure long service life of the product. Example: PAMREX cover, installed in 1989 at the bus station in the town of Caen in France — in spite of more than 5 million crossings of vehicles — still does not show any signs of material fatigue or visible damage.
The special form of the frame enables stable and trouble-free installation on the top of a manhole, and the slots in the ring ensure secure anchoring into concrete. The form of the cover and of the insert make accidental opening of the cover impossible (vacuuming effect).
The PAMREX manhole covers are designed in accordance with the requirements of the class D (400 kN), and are tested at loads of 600 kN, thus exceeding the requirements of the standard. The hinge and the tapered pattern on the cover enable automatic closing in case of overflow (flood prevention). The anti-skid surface of the cover is optimally textured for all weather conditions (snow, ice,...).
The REXESS cover is also designed for the class D (400 kN), although it weighs only 54 kg. It is the first type of cover fulfilling the requirements of the environmental standard ISO 14001. Cover and frame are coated with a water-based paint. When a vehicle drives over the cover, an automatic spring-loaded latch prevents the cover from being lifted. Stability and noise-reduction are provided by the new red composite gasket which is 300% more wear-resistant compared to the classic PE gaskets.
Certificates issued by three EU-institutions are an indication of and a guarantee for high-quality productsj.
Saint-Gobain PAM has first introduced the ductile iron covers more than 30 years ago. Hence, the results of long years of experience are reflected in excellent mechanical properties and long service-life of their products. Elasticity, high tensile strength and high impact strength are the main trumps of the ductile cast iron. These properties ensure a high level of safety and user-friendliness. They exhibit long service-life, enable simple maintenance of sewage systems, and bring about long-term economic benefits. Small weight allows for easy handling, thereby fulfilling international ergonomic requirements in relation to body strain – especially of the backbone.
The European standard EN 124 stipulates:
- Requirements for designing covers and grates for manholes and gullies (gully tops and manhole tops for vehicular and pedestrian areas)
- Testing procedures
- Marking procedures
- Production control procedures
In Slovenia the standard has been adopted as SIST EN 124.
According to this standard, the covers and grates are classified according to their load-bearing capacity, and may fall into one of the following classes:
A 15, B 125, C 250, D 400, E 600 or F 900.
The class is defined by the point of installation. Different points of installation are listed in groups from 1 to 6. Which class should be used can be derived from the table below. Determining the correct class is the responsibility of the designer. If you have doubts related to which class you should use, the next (higher) class should be used.
Table: Groups and class description
||min. A 15
||Access covers and gratings capable of withstanding a 15kN test load. For use in areas where only pedestrians and pedal cyclists have access.
||min. B 125
||Access covers and gratings capable of withstanding a 125kN test load. For use in car parks and pedestrian areas where only occasional vehicular access is likely.
||min. C 250
||Access covers and gratings capable of withstanding a 250kN test load. For use in car parks, forecourts, industrial sites and areas with slow moving traffic, also in highway locations (up to 500mm from the kerb and up to 200mm into the verge, excluding motorways)..
||min. D 400
||Access covers and gratings capable of withstanding a 400kN test load. For use in areas where cars and lorries have access, including carriageways, hard shoulders and pedestrian areas.
||min. E 600
||Access covers and gratings capable of withstanding a 600kN test load. For use in areas where high wheel loads are imposed such as loading areas, docks or aircraft pavements.
||min. F 900
||Access covers and gratings capable of withstanding a 900kN test load. For use in areas where particularly high wheel loads are imposed such as aircraft pavements.