In the "Opinions on Strengthening Urban Infrastructure Construction" issued by the State Council, it is required to strengthen the construction and transformation of underground pipe networks such as communications. The "Opinions" clarify the current key tasks of accelerating urban infrastructure upgrading and transformation. Among them, the problem of underground pipe network is prominent, and the urban internals are frequently increasing, so it is necessary to speed up the construction of underground pipelines. Let's take a look at the types and selection of municipal water supply and drainage pipes, as well as the trend analysis of municipal water supply and drainage pipes.

Six main points

First, strengthen the construction and transformation of various underground pipe networks such as urban water supply, sewage, rainwater, gas, heat supply, and communications, and carry out pilot projects for urban underground integrated pipe corridors.

The second is to strengthen the construction of urban drainage flood control and flood control facilities to solve the problem of urban water stasis.

The third is to strengthen the construction of urban sewage and domestic garbage treatment facilities.

The fourth is to strengthen the construction of urban road transport infrastructure.

The fifth is to strengthen the construction of urban power grids.

The sixth is to strengthen the construction of ecological gardens.

Type of municipal water supply and drainage pipe

The types of municipal water supply and drainage pipes mainly include plastic pipes, metal pipes and reinforced concrete pipes. Here, the plastic pipes are highlighted.

Plastic pipe

Plastic pipe plastic pipes mainly include PVC-U pipe, PE pipe, FRPP pipe and RPM pipe. The design life of plastic pipes should not be less than 50a. Municipal drainage plastic pipes shall be designed according to the pressureless gravity flow, and the structural calculation shall be carried out according to the flexible pipe design theory, and shall be buried below the freezing line.

PVC-U tube

The PVC-U pipe is a hard polyvinyl chloride pipe, and the pipe wall structure has a double-wall corrugated pipe, a reinforced pipe, a flat-wall pipe and a steel-plastic composite winding pipe.

Steel-plastic composite winding pipes are usually joined by inner casing bonding. Double-wall corrugated pipes, reinforced pipes and flat-walled pipes are usually connected by sockets and sealed with rubber rings. For flat-walled pipes, when the pipe diameter is less than 200 mm, they are often joined by bonding.

When the PVC-U pipe is used as a drainage pipe, the concentration of hydrogen sulfide gas in the pipeline is much higher than the concentration of hydrogen sulfide gas in the concrete drainage pipe, and the sealing performance of the PVC pipe to the odor is good.

When PVC-U is used as a drain pipe, its production energy consumption only accounts for 20% of the same diameter pipe cast iron pipe, low cost, anti-aging, good heat preservation effect and long service life, so it is widely used in municipal drainage. The material of PVC-U pipe is brittle and is not resistant to external pressure. Therefore, when the pressure requirement is high, the reinforced pipe or steel-plastic composite winding pipe is used, and the compression resistance is good. Based on various advantages of PVC-U pipe, it is widely used in municipal drainage and rainwater pipelines, and it is convenient for construction and installation.

PE tube

The PE pipe is a polyethylene pipe, and mainly includes a double-wall corrugated pipe, a wound structural wall pipe, a steel-plastic composite winding pipe, and a steel belt-reinforced spiral corrugated pipe.

Double-wall corrugated pipes are generally connected by socket or double sockets and sealed with rubber rings. In addition to the connection method of the double-wall corrugated pipe, the winding structure wall pipe is often welded or clamped, Huff and flanged. Steel-plastic composite winding tubes and steel belt-reinforced spiral corrugated tubes are usually joined by welding or welding.

PE pipes are divided into low-density, medium-density and high-density polyethylene pipes. In the municipal water supply and drainage field, high-density polyethylene pipes (HDPE) are widely used. The pipes have strong impact resistance, heat resistance and wear resistance. It is resistant to acid and alkali corrosion and has minimal permeability. The fast crack resistance is obviously better than PVC-U, and the heat insulation performance is good, so it is widely used in municipal water supply, drainage and rainwater. Especially in municipal water supply applications, it has the advantages of high pressure resistance, small head loss and low leakage.

FRPP tube

The FRPP tube is a reinforced polypropylene tube that is usually socketed and sealed with a rubber ring. It is mainly used for municipal drainage pipes with a maximum diameter of 1500 mm.

The pipeline shall be laid on the original foundation or backfilled with compacted foundation. The net width of the groove bottom may be determined according to the diameter of the pipe, the soil condition and the construction depth of the buried depth. When excavating trenches, the substrate elevation should be strictly controlled and the base surface must not be disturbed.

RPM tube

The RPM pipe is a glass fiber reinforced plastic sand pipe, and the connection method is generally a socket type connection or a double socket connection, and is sealed by a rubber ring.

The sand pipe is generally used for the large-diameter drain pipe. The common one is the FRP sand pipe. The advantages are strong corrosion resistance, good physical and mechanical properties, and good heat resistance. Therefore, it is used more when transporting industrial wastewater. The disadvantage is that it is easy to become brittle at low temperatures and the strength is reduced, so it is necessary to make insulation measures in colder areas.

When the plastic pipe is sealed with elastic rubber ring, when the pipe diameter is not more than 400 mm, it can be directly inserted manually. When the pipe diameter is larger than 400 mm, special pipe tools should be used to seal the pipe joint with rubber ring. For plastic pipes larger than 800 mm, the welded joints shall be welded on both sides.

Trend analysis of municipal water supply and drainage pipes

The future application trend of municipal water supply and drainage pipes will present the following characteristics:

High durability direction

The municipal water supply and drainage pipe used in China is not long, and there is still no data on the verification of its design life. However, in terms of corrosion resistance, the plastic pipe is superior to the metal pipe, so the plastic pipe is used more in the municipal water supply and drainage pipe than the metal pipe.

Flexible interface type is more widely used

The future development trend of municipal water supply and drainage pipes is to use flexible combined bearing water supply and drainage pipes, which are convenient to install and have a low probability of water leakage.

Large-caliber, multi-variety development trend

Large-diameter drain pipes are more likely to be used for reinforced concrete, and sand pipes are also more likely, but they are limited in areas with low winter temperatures. The “Twelfth Five-Year Plan” has clearly indicated that industrial waste can be used in concrete, so it can be used in large-diameter reinforced concrete.