Carbon Fiber Replaces Cast Iron Manhole Covers in Bulgaria There aren't a whole lot of things you can do with metal that cannot be replicated with composite materials like carbon fiber. Working with composites might be more expensive and time-consuming, but any part you can make out of metal you can theoretically make from composite materials too. A case in point are the carbon fiber manhole and trench covers recently installed at fuel stations in Bulgaria.
Cast iron was the preferred material when these manhole and trench covers were manufactured decades ago. When it came time to replace them though, LUKOIL Bulgaria wanted something different. They wanted something better. So they contracted with a U.S. manufacturer who provided them with carbon fiber replacements. The new covers have already been installed at 13 fueling stations across the country. Cast Iron Rusts One of the more obvious signs that the old cast iron covers need to be replaced was rust. Station owners and fuel delivery drivers both noticed progressively worsening corrosion over the last several years. No one was surprised inasmuch as cast iron does corrode. The problem is that rust gradually erodes the integrity of the metal to a point where it is no longer reliable. Engineers could have turned to something like stainless steel or hot dipped galvanized steel or iron. Stainless steel would have been cost-prohibitive. As for galvanized steel, it has its own drawbacks. They eventually went with carbon fiber because of its ability to stand up against environmental conditions. Carbon fiber will never rust no matter how long it sits outside. Cast Iron Leaks Another problem station owners and delivery drivers noticed is that the cast iron covers were tough to keep sealed. As such, many of them leaked. Water getting in under the covers only caused greater problems in the pits below. Once again, carbon fiber was the solution. Fashioning manhole and trench covers out of carbon fiber allows for much tighter tolerances that create a better fit. Any remaining gaps are easily sealed to prevent leaks. And in the future, when the covers are exposed to sunlight and temperature changes, they will not expand or contract in the same way cast iron does. This should put an end to leak issues.
Cast Iron is Heavy Finally, removing and replacing cast iron manhole and trench covers is hard work. Cast iron is heavy, unwieldy, and very difficult to work with. As long as LUKOIL Bulgaria was going to replace their cast iron covers, they might just as well choose a lightweight material, right? That's what they did. It's common knowledge that carbon fiber is significantly lighter than steel and aluminum. It's also much lighter than cast iron. A station owner or delivery driver can remove and replace a carbon fiber cover with one hand. No special tool is needed to pull the cover up and drag it along the pavement. The lighter cover is easier to use and less stressful on the body. Fewer workers will get hurt removing and replacing the covers, which is good for everyone involved. Everywhere you look it seems like composites are showing up as replacements of older materials. In Bulgaria they are replacing manhole and trench covers with carbon fiber. Across Europe, aluminum windmill blades are being replaced by carbon fiber equivalents. And across the globe, commercial airliners with carbon fiber bodies fill the skies. We are incredibly proud to be part of the carbon fiber revolution. We believe in the power of composites to transform manufacturing in a way that saves money, reduces energy use, and helps make for a more sustainable world.