Telephone: 01229 814 340

Durable manhole covers

High stress resistance

Durable manhole coversStructural Science Composites Limited [SSC] has drawn on over 20 years of knowledge in composite cover manufacture to provide the ultimate in durable manhole covers.

A leader in designing and supplying durable manhole covers for underground access. Our composite manhole solutions offer significant benefits over covers made from steel or ductile and concrete.

The main cause of fatigue is the level of induced stress in a structure deflection. If a credit card is bent back and forth it will eventually snap. That is the result of stress breaking down the structure. The material is seen to be going translucent [thinner] as the material degrades.

Our durable manhole covers are made to ensure they have a resistance to stress by a combination of design and the material it is made from.

Composites, iron and steel materials all react differently to stress induced loads depending on their elastic and plastic properties, brittleness and yield point*. These properties are important issues with regard to performance.

Steel is a very rigid so material so it experiences low deflection characteristics, but it will have permanent set above its yield point, which is well below its ultimate tensile strength. It will not fail at this point, but it will be permanently damaged

The perception is that SG iron is also very rigid but this is not the case and is likely to deflect more than a SSC composite cover. SG iron covers were introduced some years ago to combat the brittleness of grey iron and because less material can be used for a similar strength. SG iron is brittle and has no plastic deformation before reaching its ultimate tensile strength and catastrophic failure will occur

Composite materials have varying resistance to stress characteristics depending on the type of glass reinforcements used. For example carbon fibre has good rigidity, but nylon [Kevlar] has very high deflection characteristics. SSC use ‘E’ glass in a design which can accommodates the loads that would normally cause breakdown of the material and at ultimate stress level do not fail catastrophically and experience progressive failure

When the ultimate tensile strength is reached, because of the ductile property of the composite there is no catastrophic failure.

*The yield point it where a material changes from elastic deformation to plastic deformation, causing it to permanently deform. Below this all deformation is recoverable.

Durable manhole covers guaranteed

SSC composite covers are proven and guaranteed to meet the structural and fatigue requirements of AASHTO and are fully compliant with European EN124 : 1994 regulations.

Wear is negated by the combination of the materials and design. SSC composites materials are robust and will not break under normal in-service loads. Each SSC cover has a close tolerance interface with a special torsional resistant frame (D400 Composite, B125 Aluminium), which prevents movement and distortion from the eccentric forces that are a major cause of wear and failure. A recent report by a US test house indicated that the top surface would have an estimated life of 15 to 18 years based on 15,000 Foot Contact Events on the same contact point each day for the whole period. A wear indicator is fitted to all our standard covers.

If you are looking for a supplier of composite durable manhole covers look no further.

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    ThruBeam ®

    Structural Science Composites Company
    Unit 8 James Freel Court
    James Freel Close, Barrow in Furness,
    UK, LA14 2NG

    Tel: +44 (0)1229 814 340

    Registered Name: Structural Science Composites Ltd.
    Company Registration: 5553133

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