With the rapid development of the construction industry, polypropylene pipes (PPR) have also been used more. Here we introduce the application of PPR pipes and connection installation methods:
(1) In the current construction and installation projects, most of the heating and water supply are PPR pipes (pieces). Its advantages are easy and fast installation, economical and environmental protection, light weight, hygienic non-toxic, good heat resistance, corrosion resistance, good thermal insulation performance, long life and so on. The pipe diameter is one size larger than the nominal diameter. For example, PPR32 is equivalent to DN25, and PPR63 is equivalent to DN50. Pipe diameters are specifically divided into DN20, DN25, DN32, DN40, DN50, DN63, DN75, DN90, DN110. There are many types of tees, elbows, pipe clamps, reducing diameters , Pipe plug, pipe clamp, bracket, hanger. It is divided into cold and hot water pipes. The cold water pipe is a green pipe, and the hot water pipe is a red pipe. The valves include PPR ball valves, globe valves, butterfly valves, gate valves, and PPR materials with copper cores inside.
(2) The connection methods of pipes include welding, hot-melt and screw connection. PPR pipe is most reliable with hot-melt connection, easy operation, good air tightness and high interface strength. The pipe connection uses a hand-held fuse for hot-melt connection. Before connecting, remove the dust and foreign objects from the pipes and accessories. When the red light of the machine is on and stable, aim at the pipes (pieces) to be connected. DN <50 hot melt depth is 1-2MM, DN <110 hot melt depth is 2-4MM. When connecting, turn the pipe end without rotation. Inserted into the heating jacket to a predetermined depth. At the same time, the tube is pushed on the heating head without rotation to heat it. After the heating time is reached, the tube and the tube are immediately removed from the heating jacket and the heating head at the same time, and they are inserted into the required depth quickly and uniformly without rotation. A uniform flange is formed at the joint. During the specified heating time, the newly welded joint can also be corrected, but it is strictly prohibited to rotate. When heating pipes and fittings, prevent excessive heating to reduce the thickness. The pipe is deformed in the pipe fitting. Do not rotate during hot-melt intubation and calibration. There should be no open flame at the operation site, and it is strictly prohibited to bend the pipe with open flame. Align the heated pipes and fittings vertically and push them lightly to prevent bending of the elbow. After the connection is completed, the pipe and the fitting must be held tightly for a sufficient cooling time, and they can be released after cooling to a certain degree. When the PP-R pipe is connected to metal fittings, a PP-R pipe with metal inserts should be used as a transition. The pipe fitting is connected to the PP-R pipe by hot-melt sockets and connected to metal fittings or hardware accessories of sanitary ware. When using thread connection, it is better to use polypropylene raw material tape as the sealing filler. If a faucet is connected to the mop pool, an internal elbow (with internal threads) is installed at the end of the PPR pipe. During the installation of the pipeline, do not use excessive force to avoid damaging the screw fittings and causing leakage at the connection. Pipe cutting can also be cut with a special pipe: the bayonet of the pipe shears should be adjusted to match the diameter of the pipe being cut, and the force should be evenly applied when rotating and cutting. After cutting, the complete round should be used for the fracture. When the pipe is broken, the section should be perpendicular to the pipe axis without burrs.
(3) During the pipeline installation process, hydraulic tests can be carried out in layers or single sets. The working pressure and test pressure of all pipelines are: 0.4Mpa in the low zone, 0.6Mpa in the test pressure, 0.6Mpa in the high and middle zone, and 0.9Mpa in the test pressure. Comprehensive inspection, check the installed pipes, valves, gaskets, fasteners, etc., all meet the design and technical specifications, remove the parts that are not suitable for pressure testing with the pipeline, replace them with temporary short pipes, and close all openings , And irrigate from the lowest point, deflate from the high point. Purge the pipes that have passed the pressure test until the dirt is washed away, and do a good job of purging and cleaning records and pressure test records. The test pressure is 1.5 times the working pressure of the system, but shall not be greater than the allowable pressure of the pipe. Water should be poured slowly during the test, and the seal should be checked after filling. The pressurization should be slowly increased to the test pressure with a hand pump, stabilized for 1 hour, the pressure drop is less than 0.05Mpa, and then reduced to 1.15 times the working pressure for 2 hours, and the appearance inspection shall be performed. 0.03Mpa is qualified.
(4) Pay attention to sharp objects when handling and installing pipelines during installation to prevent pipeline damage. During pipeline installation, prevent organic pollutants such as paint from coming into contact with pipes and fittings. Openings where installation is interrupted or completed must be temporarily closed to prevent debris from entering. The water supply pipeline system should be flushed with water before acceptance. The flow rate of the flushing water should be greater than 2m / s. There should be no dead angle when flushing. Each tap of the water distribution point should be opened. The lowest point of the system should be provided with a water outlet. The cleaning time should be controlled at the flushing outlet. After the drinking water system is flushed, 20-30mg / l of free chlorine water is used to fill the pipes for disinfection. Chlorinated water should remain in the tube for more than 24 hours. After the pipeline is disinfected, it is rinsed with drinking water and sampled and inspected by the health management department. The water quality can only be delivered after it meets the current national standard "Sanitary Standards for Drinking Water". Within 30 minutes, two boosts are allowed to rise to the specified test pressure. Pay attention to the change of pipe diameter when budgeting and feeding. As shown in the chart, the pipe (piece) of PPR25 is DN20. Be sure to use the same manufacturer's product, because different manufacturers' products contain different proportions of ingredients. It may cause inadequate adhesion or inadequate adhesion.