Selection of PE-RT pipe：
The quality of the piping system depends not only on the pipe itself, but also closely related to the conditions used, such as temperature and pressure. Inappropriate selection of pipes often leads to serious quality accidents. When selecting pipes, it should be in accordance with the use condition level 4 and floor heating in ISO10508 "Thermoplastic pipes and fittings for cold and hot water systems", and the design stress is 3.34MPa.
With the continuous development of the floor heating industry, many domestic plastic pipe manufacturers that did not produce PE-RT pipes have also increased their investment in this product. At present, the PE-RT pipe manufacturers have rapidly developed from the original several to the top. Hundreds.
In the initial stage of the development of PE-RT pipes, since the temperature and pressure resistance of PE-RT material itself is weaker than that of cross-linked polyethylene pipes and aluminum-plastic pipes, the application areas of this product are mainly concentrated in floor heating systems and are rarely used. In the radiator heating system. However, with the continuous development of polymerization technology, according to the established international standard ISO22391-2 for PE-RT pipes, there are currently two types of PE-RT pipes on the market, namely type Ι and type Π, of which type Π PE-RT pipe The temperature and pressure performance of the radiator has reached the requirements of the current domestic radiator heating system. The PE-RT national standard that is being developed also continues the international standard's classification of PE-RT materials.
By comparison, it can be found that the type I PE-RT pipe has an inflection point when it is used for a long time at the typical temperature of 80°C, 90°C, and 95°C, and its temperature and pressure resistance is lower than that of the type II PE-RT material.
Due to the change of the installation method, the domestic cold and hot water system has been transformed from the original double-pipe parallel type to the use of a sub-catchment water supply. This installation method requires relatively high flexibility of the pipe due to the random direction of the pipeline. Due to the better flexibility of PE-RT pipes, the use of coiled pipes can greatly reduce the use of accessories in the pipeline, which facilitates construction and reduces costs for users.
Problems：
Driven by economic interests, fake and inferior PE-RT pipes have appeared on the market, and their counterfeiting methods are mainly reflected in the following two aspects:
Add linear low-density polyethylene such as 7042 linear low-density polyethylene to reduce costs. This kind of pipe is often difficult to pass the short-term hydrostatic strength test. At present, it is mainly used by some small manufacturers, and these small manufacturers generally do not have testing equipment.
Use non-PE-RT pipe special medium-density polyethylene materials to produce PE-RT pipes, such as medium-density MP3410 and 3082. At present, the companies that sell this kind of raw materials are mainly trading companies, and the manufacturers often do not know the inside story. The short-term performance of the pipes produced from these raw materials may not pass the test. This production method is relatively professional and has a relatively strong concealment, which is likely to cause quality accidents in 5 or 10 years. It is understood that some large-scale domestic PE-RT manufacturers have also been involved.
The quality of PE-RT pipes depends not only on the raw materials, but also on the quality control of the pipes from production to delivery. Pay close attention to the wall thickness and appearance of the pipe during the production process to ensure that the wall thickness of the pipe is relatively uniform. In addition, there should be no impurities or other stripes affecting the performance of the pipe on the surface of the pipe wall. Since PE-RT pipes are generally produced in the form of coiled pipes, the entire coil of pipes should be pressure tested during the factory inspection to ensure that the entire coil of pipes are qualified products. However, some small domestic PE-RT pipe manufacturers are negligent in management and rarely perform real-time inspections during the production process, which will inevitably produce a large number of unqualified products. In the factory inspections, these companies often only do sampling inspections, so that a large number of unqualified products enter the construction site, laying many hidden dangers to the underfloor heating project.
In addition, the PE-RT production line used by some manufacturers is modified from the PP-R production line. Because the melting point and fluidity of the two materials of PP-R and PE-RT are different, the use of this production line to produce PE-RT pipes will have a greater impact on the performance of the pipes, and it will also bring more Many hidden dangers.
