If the city's drainage facilities can not keep up. it is likely to cause ponding. In the past, most manhole covers were made of cement and gray cast iron, but now they are different. There are many raw materials for manhole covers, and composite resin is one of them.
The resin manhole cover is generally made of polymer composite material, so the recovery value is not high. Some manufactures use unsaturated resin, glass fiber and other materials and reinforced skeleton through special production process. The composite of the resin is also natural and synthetic, so the effect of the two is naturally different. Natural resin refers to the amorphous organic substances extracted from the natural animal and plant secretions,such as rosin, amber, shellac, etc.; synthetic resin refers to the resin products obtained from the chemical synthesis of simple organic substances or the chemical reaction of some natural products. Synthetic resin is an important part of plastics.
The resin manhole cover is generally made of polymer composite material, so the recovery value is not high. Some manufactures use unsaturated resin, glass fiber and other materials and reinforced skeleton through special production process. The composite of the resin is also natural and synthetic, so the effect of the two is naturally different. Natural resin refers to the amorphous organic substances extracted from the natural animal and plant secretions,such as rosin, amber, shellac, etc.; synthetic resin refers to the resin products obtained from the chemical synthesis of simple organic substances or the chemical reaction of some natural products. Synthetic resin is an important part of plastics.
It can be seen that the resin composite manhole cover often does not blindly pursue what is pure natural. If pure resin is used, then after such a long time of development, the quality of manhole covers produced and used may have some problems. The production technology of resin manhole cover is also relatively mature. As for the price of resin manhole cover, it is much cheaper than ductile iron.
What about resin manhole covers? The thinner part of the resin manhole cover should be considered with external feeding, and the curing shrinkage process needs external pressure support; the resin manhole cover does not need feeding or only needs feeding; the feeding is not limited to external feeding; the chill can adjust the solidification speed at the thick hot spot and the temperature gradient of the casting, and its feeding effect on the resin manhole cover is conditional.
The above is the introduction of the expensive resin composite manhole cover. In fact, the quality of manhole covers is often directly proportional to the price, which requires us to make a good comparison.