Metal manhole covers, as we know them, first appeared with the advent of gas companies and waterworks, beginning in the late 1840s. The cover surfaces were originally designed with raised patterns to prevent horses' hooves from slipping on them when wet. These decorative heavy cast iron covers were used to protect and allow access to the vast underground network of sewer systems, water pipes, and utility and telephone lines.
For years artists have decorated manhole covers across their towns and cities to reflect local culture, history, landmarks, and festivals.
The Composite Age
Today composite materials are used in wind energy, marine, construction, aerospace, military/ defense, automotive, sporting goods, pipes, access covers, tanks and many more applications. Composites offer several advantages over traditional materials: higher tensile strength, lighter weight, greater corrosion resistance, no resale value (reducing danger of theft), better surface finish, and easier processing.
Connecticut-based composite manhole cover manufacturer Fibrelite now offers company logos and other brand markings on its full range of access covers. Any style logo or other marking can be permanently molded into the upper surface of the cover, in single or multiple colors. Ideal for branding and product identification, or to blend in with the color or layout of a building, plaza, or sidewalk, composite covers can be molded in nearly any color or combination of colors.
By introducing the pigment directly into the composite resin during the closed molding process, Fibrelite ensures that the color is not merely applied on the surface of the cover, but is instead evenly and completely infused throughout the composite cover. Thus, it will not fade or wear over time.
Health and Safety Issues
Although they can be more expensive than traditional materials such as aluminum, steel, and concrete, composites are becoming more favorable where corrosion resistance, thermal conductivity, and other performance essentials are critical to a specific application. And let's not forget the health and safety issues and costs associated with lifting heavy metal. ?According to a study published by the League of Minnesota Cities entitled "Muscling Manhole Covers and Other Ergonomic Information," workers are frequently injured while attempting to remove heavy cast iron manhole covers at an average cost of nearly $100,000 per incident.
While not every application currently requires the composite alternative, the costs of metal theft, manual-handling injury claims, and corrosion are causing many industries to rethink traditional materials and begin to consider the use of modern composite products.
"Customers as diverse as electrical and energy utilities, water and water treatment plants, commercial and industrial developments, resort hotels and colleges and universities are using our molded marking and coloring process in unique and highly visible ways," confirms Fibrelite's president, Jim Goodman. "Our covers are improving the appearances of city pavements, college campuses, sports arenas, and even the interior spaces of corporate office buildings.
"Our customers are also using color as a quick and reliable coding method to identify what's below ground. Color-coding covers provides maintenance and emergency personnel with more accurate information about any hazards or special conditions related to the underground infrastructure."
Additional Benefits of Composite Covers Include:
Lightweight design (typically 1/3 the weight of cast iron equivalent) dramatically reduces the risk of occupational injuries , a huge issue for municipal governments Watertight cover design reduces most stormwater infiltration into sewers, lowering the cost of treatment as less liquid arrives at the treatment plants Composite covers will not rust when exposed to saltwater or coastal climates Composite covers will not rust when exposed to common sewer gases Composite covers will not rust when exposed to wastewater and commonly disposed chemicals found in wastewater.
