Currently, PVC is the primary plastic pipe used in domestic water supply networks. PE pipes were introduced relatively recently and are relatively rare. With their development and application in the European water supply industry, PE pipes have begun to attract attention. PVC, in particular, faces increasing environmental pressure, including concerns about excessive levels of heavy metals such as lead and cadmium. So, what are the differences between PVC and PE pipes?
Since the early 1980s, China has vigorously promoted the use of PVC pipes, formulating a series of policies, regulations, and standards, and accumulating considerable experience. Today, comprehensive product standards, testing methods and procedures, and construction engineering specifications exist, standardizing product dimensions and quality indicators and ensuring product interchangeability. This demonstrates that the development of PVC water supply pipes has reached a mature stage, ensuring both product and construction quality, and thus guaranteeing the effectiveness of PVC water supply pipes.
The international standard for PE pipes for water supply (ISO 4427) wasn't officially released until 1996. My country drafted the national standard GB/T 13663 in 1999, based on ISO 4427, and implemented it in 2000. However, standards and engineering specifications for PE pipe fittings are still under development. This indicates that the quality of domestic PE pipes is still unstable, and the supporting system for pipes and fittings is not yet complete, making it difficult to ensure quality during production and construction.
Comparison of Mechanical Properties of Two Pipe Materials
1. Material Strength Comparison at Room Temperature
PVC has significantly higher short-term and long-term strength than PE.
2. Comparison of Minimum Required Strength (MRS) and Safety Factor (C)
Both theoretical and practical experience demonstrate that PVC has significantly higher MRS and safety factors than PE, meaning it offers greater long-term strength and safety. Therefore, for pipes with the same 75mm diameter, pipes made from PVC can have much thinner walls than those made from PE. This is because PE's strength at room temperature and long-term strength are not as high as PVC's, and thus, strength can only be increased by increasing the wall thickness. For pipes with the same wall thickness, PE pipes will not meet the required strength. For pipes with the same diameter, PVC pipes can carry a larger water flow than PE pipes. Conversely, to achieve the same water flow rate, a larger diameter PE pipe is required, significantly increasing the project cost. This demonstrates that PVC's higher strength and rigidity make it economical for water supply pipes.
3. Lifespan Comparison
Polyvinyl chloride (PVC) is a polar macromolecule, more stable than monomeric vinyl chloride (PE) and some smaller molecules, and therefore less susceptible to environmental influences. However, the emergence of polymers such as cross-linked vinyl chloride will improve this aspect.