Common problems and solutions of PPR pipeCommon problems and solutions of PPR pipe
What is PPR pipe? In the process of using ppr pipe, there will always be some problems that make many customers overwhelmed. In order to help you better understand the knowledge of PPR pipe, I have compiled common problems and solutions for PPR pipe for everyone. You help.
PPR pipe is also called three-type polypropylene pipe and random copolymer polypropylene. The random copolymer polypropylene can be extruded into pipe material and can also be injected into pipe fittings. The random copolymer of polypropylene is also a kind of polypropylene. The basic structure of its polymer chain is modified by adding different kinds of monomer molecules. Ethylene is the most commonly used monomer, which causes changes in the physical properties of polypropylene. Compared with pp homopolymers, random copolymers have improved optical properties (increased transparency and reduced haze), improved impact resistance, increased flexibility, lowered melting temperature, and thus lowered thermal fusion temperature ; At the same time in terms of chemical stability, water vapor barrier properties and organoleptic properties (low odor and taste) is basically the same as homopolymer. It is used in the fields of blow molding, injection molding, film and sheet extrusion processing, as food packaging materials, pharmaceutical packaging materials and daily consumer products.
1. Why does PPR pipe have low temperature brittleness?
Answer: PPR is a random copolymer polypropylene, which is what we call type III polypropylene. It is obtained by random copolymerization of propylene monomer and a small amount of ethylene monomer under the action of heat, pressure and catalyst.
The ethylene monomers are randomly distributed into the long chain of propylene, where the ethylene monomers are generally controlled between 3-5%. The ethylene content and the polymerization method of ethylene and propylene determine its cold brittleness.
In the case of low temperature, especially during winter construction, the flexibility of the pipe at low temperature is reduced, the rigidity is enhanced, and it is brittle.
Under the impact of external force or excessive unexpected load, the pipe may crack straight. Inconvenience to construction. Therefore, the relevant national regulations have made clear requirements for this issue.
During winter construction, attention should be paid to the characteristics of low-temperature brittleness of building water supply polypropylene (ppr) pipes, and corresponding construction plans should be worked out. GB / T50349-2005 has detailed regulations on this.
2. The manifestation of PPR pipe cold brittleness in practical application
Answer: When the ambient temperature is low, the toughness of the PPR pipe decreases and it appears brittle. When the pipe is impacted or stressed by an external force, a linear cracking phenomenon occurs, and the cracking starts from the inner pipe and extends to the outer pipe.
After the tube is cracked due to the force of a point, this crack will grow rapidly along the axis of the tube in an instant. This characteristic is called rapid crack growth.
In addition, during the transportation, construction site and installation process, the pipe is injured due to external forces in the winter, and the brittleness and toughness (when hot water is transported) will burst during use.
3. The misunderstanding that everyone often goes into-the PPR water pipe that can be broken is the poor water pipe
Answer: This method of judgment is wrong. Can the PPR tube be cracked? This is a misunderstanding to judge whether the PPR is good or bad. This does not check whether the PPR is good or bad, because the performance of the ppr material itself depends on the ambient temperature Degree of change.
In the case of low temperatures, especially in winter, the tube has reduced flexibility and increased rigidity at low temperatures, and it is brittle. Under external impact or excessive accidental load, the pipe may break. Inconvenience to construction.
Therefore, the relevant national regulations have made clear requirements for this issue. During winter construction, attention should be paid to the characteristics of low-temperature brittleness of building water supply polypropylene (ppr) pipes, and corresponding construction plans should be worked out. GB / T50349-2005 has detailed regulations on this.
On the contrary, some fake and inferior PPR tubes added with other raw materials are not easy to smash! The true ppr that can transport both high-temperature hot water and cold water can be used for 50 years. It can be cracked, especially in the case of lower temperatures. This is the low-temperature brittleness of ppr.
If the ppr water pipe cannot be broken, it can basically be concluded that it is not a real ppr material. The advantages of ppr tubes are mainly reflected in higher creep resistance.
The good tube of pure ppr material has low temperature and brittleness, and it is particularly obvious in the environment below 5 ℃, so the good tube can break, and it is not the ppr tube, but the PP-B or cold Miscellaneous materials.