Polypropylene (PPH) pipes are widely used in many industries such as chemical, food and pharmaceutical due to their excellent physical and chemical properties. However, temperature, as a key factor affecting the performance of PPH pipes, is directly related to the durability, safety and effectiveness of the pipes.
Temperature range and performance
The applicable temperature range of PPH pipes is usually between -20°C and 90°C. Beyond this range, the physical properties of PPH pipes may decrease significantly, affecting their normal use. Specifically, high and low temperatures have different effects on the performance of PPH pipes.
Under high temperature conditions, the mechanical strength and rigidity of PPH pipes will be significantly reduced. The increase in temperature leads to the enhanced mobility of polymer chains, which causes deformation and increased fluidity of the material. When the temperature exceeds 90°C, PPH pipes may soften, deform, or even lose their pressure bearing capacity. This phenomenon is particularly important in pipeline systems that need to withstand high-temperature fluids and must be given full attention.
Relatively speaking, low temperature environments have a more significant effect on the toughness of PPH pipes. When the temperature drops below -20°C, PPH pipes may become fragile and prone to brittle cracking. Under low temperature conditions, the impact toughness of the pipe decreases, and it is easy to cause rupture when external force impacts, causing leakage or other safety hazards.
Thermal expansion and contraction
PPH pipes experience thermal expansion and contraction when the temperature changes. Polypropylene has a high linear expansion coefficient of about 0.15-0.20 mm/m·°C. This characteristic means that the length and diameter of the PPH pipe will change accordingly when the temperature changes.
In a high temperature environment, the expansion of the PPH pipe may cause loosening or leakage at the pipe connection. Therefore, when designing the pipeline system, it is necessary to consider the impact of thermal expansion and reasonably set the support and fixing points to ensure that the pipe can expand and contract freely when the temperature changes.
Conversely, in a low temperature environment, the contraction of the PPH pipe may cause the tightness of the pipe connection to decrease, thereby increasing the risk of leakage. Therefore, the sealing of the connection must be ensured during installation to prevent problems when the temperature drops.
Thermal aging
In a high temperature environment, the thermal aging rate of the PPH pipe is significantly accelerated. With the extension of the service time, the following changes may occur in the pipeline material:
First, high temperature will cause the molecular chain of the PPH pipe to break, which will cause a decrease in the strength and rigidity of the material. This phenomenon is particularly obvious under long-term high-temperature operation, which may lead to early failure of the pipeline.
Secondly, under high temperature environment, the color of PPH pipes may change, and the surface may fade and crack. This not only affects the appearance of the pipe, but also its performance, especially in applications with high requirements for appearance.
In order to delay the process of thermal aging, many PPH pipe manufacturers will add anti-aging agents during the production process. These additives can effectively improve the heat resistance of PPH pipes, thereby extending their service life.
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