Composite Manhole Valve

GRP (Glass Fiber Reinforced Polyester) composites produced by this method, with approximately 25% glass fibers and produced with very heavy presses, have a special mechanical strength of up to 2.5 times that of steel.
Therefore, despite the fact that the composite valves produced in this way are up to 70% lighter than similar cast iron valves, they can show equal or even more mechanical properties than the desired cast iron valves.