Precautions for pipeline construction in winter with CPVC glass fiber reinforced composite power cable pipe
The weather has been turning cold, and many areas in the north are coming to the heating season. Special reminder: the use of plastic pipe in the cold area, lined with CPVC FRP composite cable pipes must pay attention to the characteristics of low temperature brittle material, take necessary antifreezing measures, when the environment temperature is below 0 DEG C, the cold water pipe is easy to freeze and volume expansion (the same quality of water, the solid is greater than the size of the liquid when the expansion force, volume), may cause pipe rupture.
The following points for the use of plastic pipes in winter are described as follows:
One, floor heating pipe
The environment temperature should not be lower than 3 C in the construction of low temperature hot water surface radiation heating project. When PE-RT tube is used as heating pipe, the ambient temperature should not be less than 0. In the environment under 0 centigrade, the environment should be used to improve the environment temperature.
For floor heating pipes, such as PE-RT, PB and oxygen resistance pipe, the small air compressor is used to clean and blow dry in time after pressure test.
Two, PPR winter construction attention
Winter is the multiple season of pipeline engineering construction accidents. Because the material performance of PPR decides its low temperature in winter, such as construction, loading and unloading, transportation and so on, it is easy to appear pipe rupture and fracture in different degrees. In this environment, not only has a great influence on the pipeline construction, and difficulty in the construction, to ensure that users of pipeline construction safety, effectively prevent winter caused by pipeline construction Water Leakage trouble and unnecessary loss of the PPR pipe in winter construction precautions are summarized as follows, must pay attention to oh.
The properties of 1.PPR materials are low temperature brittleness at low temperature. Under external force, when the external force is greater than its bearing limit, it is very likely to produce rupture and so on. The national "technical specification for polypropylene pipe engineering for building water supply water" (GB-T53046-2005) has been explained in detail, so the cold brittleness of PPR should be paid attention to in winter construction.
The main form of expression: the fracture of different conditions is produced by different force parts, and the rupture of the pipe is mainly caused by strong impact of external force during the handling or construction. The general appearance is not easy to detect, often appears in the pipe fittings connection, let the person mistaken to be the welding quality problem and the sand eye. Because of the external force, the crack is tight outside the internal tension, and can also bear the pressure of the water supply of 2-4KG, which is mistaken for the quality of welding. Sometimes the water line is not found in the short term after the user is open to the water, and the water is leaking after a period of time. Before the pipe is connected, the damaged part should be removed, and the water pressure test of the pipe is completed in time.
2. pipe handling. PPR pipeline brittleness is very strong at low temperature, so it should be light and light in transportation, handling and loading and unloading. No throwing, throwing, drag, rolling and other phenomena, caused by the rupture of the pipe and pipe fittings and pipe is not easy to find, only through the water pressure test can find problems.
The welding temperature of 3.PPR is 250 + 10 C. High temperature welding is strictly prohibited, because high temperature will make the welding head carbonized and its polymer material will deteriorate, even if the water pressure test interface is temporarily difficult to find water leakage. Water leaks will occur in the near or next three months or even three years. So the welding temperature is the key to the quality of the pipe welding. When the temperature is below 5 centigrade, the protection measures should be taken to adjust the heat absorption time of the welding. The general endothermic time was extended by 50%.
4. water pressure test. After the pipeline is installed, the water pressure test is done in time. The pressure of cold water pipe pressure is 1.5 times of the working pressure, but it should not be less than 0.9MPA. The test pressure of hot water pipe is 2 times of the working pressure, but it must not be less than 1.2MPA. The steady pressure time is 30 minutes, the water pressure test in winter should finish the water in the pipe in time. The long winter without water, if there is no reliable insulation measures should also be in the pipeline of water, to prevent the cracking and spalling of pipeline.
Is the PPR water pipe that is not easy to crack is a good water pipe?
1, why is there a low temperature brittleness in the PPR tube?
Answer: PP-R is random copolymerized polypropylene, that is what we say type III polypropylene. It is obtained by random copolymerization of propylene monomer and a small amount of ethylene monomer under the action of heating, pressure and catalyst.
The ethylene monomer is randomly distributed in the long chain of propylene, in which the ethylene monomer is generally controlled between 3-5%. The ethylene content and the polymerization of ethylene and propylene have the characteristics of cold brittleness.
In the case of low temperature, especially during the winter construction, the flexibility of the pipe is reduced at low temperature, and the rigidity is strengthened, which shows brittleness.
Under the effect of external force impact or too large accidental load, there may be a straight line cracking of the pipe. It brings inconvenience to the construction. To this end, the relevant national norms have made a clear demand for this problem.
In winter construction, we should pay attention to the characteristics of low temperature brittleness of construction water supply polypropylene (PP-R) pipe and make the corresponding construction plan. GB/T50349-2005 has detailed rules for this.
The manifestation of 2 、 PPR tube cold brittleness in practical application
Answer: when the ambient temperature is low, the toughness of PPR pipe decreases, showing brittleness. When the pipe is impacted or stressed by external force, there will be a linear cracking phenomenon, and the cracking will start from the inner tube and extend to the outer tube.
When the pipe is cracked by the force of a point, it will increase rapidly along the axis of the pipe in the instant. This property is called fast crack growth.
In the course of transportation, construction site and installation process, the pipe material will be brittle and ductile (when transporting hot water) in the process of transportation, site and installation.