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FAQ's This is a selection of the most frequently asked questions about our composite access covers. If you have a question that is not answered below, or you would like further information, please contact us with your enquiry.
Product details 2. Do composite road covers comply with AASHTO and Class D400 standards? 3. How do composite covers deal with stray voltage? 4. What are the wear properties of the embedded aggregate tread? 5. Will composite covers burn? 6. Can composite covers be made water tight? 7. Can composite covers be manufactured in different colours? 8. Do composite covers have a scrap or resale value? 9. I have below-ground monitoring equipment; do I need an external aerial?
Comparisons with traditional covers 10. Compared to old style cast-iron covers, how corrosion-proof is a composite cover?
Life-span of SSC covers 13. What is the expected life of each composite cover? 14. How do composite covers compare to cast iron in terms of whole life costs? 15. Can composite covers be locked?
Environmental 16. Are composite products green?
Q1: Compared with traditional cast-iron covers, what is the weight ratio of an SSC composite cover for “in road” use?
The development of ThruBeam™ technology, combined with new hybrid resin systems, has resulted in SSC composite covers. They are only 1/3 the weight of cast-iron covers and have comparable load capacity. The reduced weight dramatically reduces the risk of injury to workers. Associated health and safety issues, which can lead to compensation claims, are also significantly reduced.
Q2: Do composite road covers comply with AASHTO and Class D400 standards?
Yes. SSC covers have been rigorously tested in the US and exceed all US standards. They have also been certified to be compliant with the rigorous EN124: 1994. Class D400 standard.
Q3: How do composite covers deal with stray voltage?
SSC composite covers have a very high electrical resistance value and do not conduct electricity. They therefore provide a passive safety feature, removing the risk of electrocution to pedestrians and potential litigation and insurance issues.
Q4: What are the wear properties of the embedded aggregate tread?
Wear testing has shown that when considering pedestrian foot contact events using leather soled footwear, the life is in excess of 75,000,000 contact events. Pedestrian foot traffic, due to the sliding action of a foot contacting the ground, produces a higher wear rate than the rolling contact of a tyre.
Q5: Will composite covers burn? SSC covers do not support combustion. If burnt, they produce very low levels of smoke and no dangerous chemicals such as bromides.
Q6: Can composite covers be made water tight?
Yes. SSC covers can incorporate watertight seals if required.
Q7: Can composite covers be manufactured in different colors?
Yes. They can be supplied in a range of standard colors, or customised at additional cost.
Q8: Do composite covers have a scrap or resale value.
Composite covers have no scrap or resale value. This means they much less likely to be stolen than cast iron covers, which have significant scrap value.
Q9: I have below-ground monitoring equipment; do I need an external aerial?
No. Composites are transparent to radio waves so you can transmit directly from the monitoring equipment.
Q10: Compared to old style cast-iron covers, how corrosion-proof is a composite cover?
Composite covers do not corrode in water or salt water and do not have a galvanic reaction with metals. They also have excellent resistance to many chemicals. For example, they are suitable for use with high strength chlorine solutions.
Q11: Cast iron covers polish and become very slippery particularly when wet, how do composite covers compare? SSC covers employ embedded aggregate technology in the treads. The aggregate is extremely hard, cannot be polished and provides excellent slip/skid properties even in wet conditions. The coefficient of friction value when wet is typically 0.7 and this value will be retained throughout its life. Cast iron is typically 0.35, which is not sufficient to provide a slip resistant surface for pedestrians, the recommended minimum value being 0.4.
Q12: Cast iron covers transfer heat very quickly. They get very hot when located over a heat source such as steam distribution lines. How do composite covers compare?
The thermal conductivity of the SSC covers is typically only 1/150 that of steel and cast-iron. Our covers provide exceptional thermal insulation performance. An SSC cover designed for steam applications was maintained at 400ºF on its lower face and did not exceed 125ºF on the top face of the cover – providing protection for pedestrians. Q13: What is the expected life of composite covers?
Composite covers have been in service since 1985 and SSC covers have a 15 year guarantee.
Q14: How do composite covers compare to cast iron in terms of whole life costs?
SSC covers are more expensive initially, however, whole life studies show the composite option provides the overall lower cost option. It is the installation cost and not the cover cost that absorbs most of the cost. Therefore, the cover that lasts the longest will have the lowest life cost. Composites do not corrode and are designed to provide an extended life, which accounts for them being the low cost option.
Q15: Can composite covers be locked?
Yes, lock options can be provided.
Q16: Are composite products green?
Compared with cast iron and steel yes. The much lower weight, combined with a manufacturing process which requires only low level heat, ensures that in the manufacturing process, subsequent distribution and installation, they require far less energy. Therefore, composite covers have a significantly reduced level of embedded carbon.
Prepared by: Graeme Roberts / John Newton Date: 12st October 2009 © Structural Composites Technologies LLc
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