Effect of PE pipes in transporting hydrogen chloride gas
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In the chlor-alkali industry, PVC pipes are commonly used for transporting HCL gas. Our company has encountered frequent leakage problems with these pipes; last year, some of them were replaced with steel-reinforced PE pipes during maintenance. These new pipes have been in use for a short time so far, and no problems have occurred, but it is unknown what the long-term performance will be. Are there any companies in the same industry that have been using steel-reinforced PE pipes for a long time? Or other materials? How is it working?
Based on experience, if a leak occurs, it is either due to the use of defective materials or high temperatures that cause the pipes to soften and thus develop defects. If the temperature of the HCL gas is above 50°C, it is recommended to replace UPVC with CPVC, as CPVC can withstand temperatures up to 100°C. PE steel-reinforced pipes consist of high-density polyethylene with a wire mesh framework added inside; their strength is much higher than that of regular PE. Their temperature resistance is similar to that of high-density polyethylene, slightly better than that of UPVC – around 70 degrees Celsius. For strongly corrosive gases such as HCl, it is recommended to use pure plastic pipes, as high-density polyethylene may develop surface defects over time. When hydrogen chloride penetrates through these defects and comes into contact with the steel, the steel will be corroded. There are many such cases, especially when the pipes are not installed properly. The greatest advantage of PE steel frames is their high strength; pure plastic cannot withstand a pressure of 2.0 Mpa, but PE steel frames can. Obviously, PE steel frames are materials that sacrifice corrosion resistance in order to increase strength. Since the pressure of HCL in chlor-alkali plants is generally low, it is recommended to use CPVC instead; it is easy to install and its price is likely to be low as well.