The Differences Between PE Pipes and HDPE Pipes

PE pipes polyethylene-pipe are made of polyethylene plastic. As the most basic type of plastic, Polyethylene has excellent resistance to most household and industrial chemicals. Common items like plastic bags and cling film are made of PE.

Polyethylene pipes can be generally classified into three types: low-density polyethylene pipes (LDPE pipes), medium-density polyethylene pipes (MDPE pipes), and high-density polyethylene pipes (HDPE pipes).

I. Low-Density Polyethylene (LDPE for short)

Low-density polyethylene is usually produced by high-pressure polymerization, with a density of 0.910-0.925g/cm³. The molecular structure of LDPE is a linear macromolecule with many side chains. The varying lengths of these side chains on the main chain affect the regularity of macromolecular arrangement, making the packing loose and hindering the crystallization of polyethylene. Therefore, its crystallinity is only 55% – 65%. LDPE has a low melting point and is soft. The long side chains give it low viscosity at high shear rates during processing and high melt strength during stretching, making it very suitable for blow molding processes. It is mainly used in the production of agricultural films and heavy packaging films.

II. Medium-Density Polyethylene (MDPE for short)

Medium-density polyethylene is produced using efficient catalysts under medium and low pressure through copolymerization with α-olefins to control its density (0.926-0.940g/cm³), with a crystallinity of 70%-80%. Due to its numerous and long side chains, the density and crystallinity decrease, giving MDPE better flexibility and low-temperature properties. However, its tensile strength, hardness, and heat resistance are inferior to those of high-density polyethylene. The copolymerization of olefins increases the interlamellar connection chains in the MDPE crystal, significantly improving its resistance to slow crack growth and long-term mechanical strength retention compared to LDPE. MDPE can be used in the production of pressure pipes, delivery pipes, various containers, and packaging films.

III. High-Density Polyethylene (HDPE for short)

High-density polyethylene (HDPE) is produced by low-pressure polymerization, presenting a linear structure with a density of 0.94-0.965g/cm³ and a crystallinity of 80%-95%, appearing as white powder or granules.

Compared to low-density polyethylene, HDPE has fewer side chains and is nearly linear in structure, with regular molecular arrangement and tight packing. Therefore, it has a high crystallinity and density, with a relative molecular weight of hundreds of thousands to millions, and a narrow range of melt flow rates. HDPE has high rigidity and toughness, excellent mechanical strength and heat resistance, as well as good resistance to deep agents and steam permeability. Among all types of polyethylene, HDPE has the lowest permeability and the strongest corrosion resistance, and also has good stiffness. It is mainly used in the production of various pressure pipes and injection-molded products.

Therefore, HDPE pipes are a type of PE pipe, but compared to ordinary PE pipes, HDPE pipes have superior performance, which can be summarized as follows:

Different pressure-bearing capacity: HDPE pipes must withstand certain pressure, and usually require PE resins with high molecular weight and good mechanical properties, such as HDPE resins, which have a strength nine times that of ordinary polyethylene pipes (PE pipes).
Different wear resistance: Among all engineering plastics, HDPE has the best wear resistance. The higher the molecular weight, the more wear-resistant the material becomes, even surpassing many metal materials (such as carbon steel, stainless steel, bronze, etc.). The wear resistance of ordinary PE is only one-tenth that of HDPE.
Different applications: General PE pipes (medium-density polyethylene pipes) are suitable for transporting gaseous artificial gas, natural gas, and liquefied petroleum gas, while low-density polyethylene pipes are used as soft pipes. HDPE pipes (high-density polyethylene pipes) are mainly used for transporting natural gas, municipal water supply systems, indoor water supply systems in buildings, outdoor buried water supply systems, and buried water supply systems in residential areas and factories, as well as for the repair of old pipelines, water treatment pipeline systems, and industrial water pipes in gardens, irrigation, and other fields. HDPE pipes can be used as the successor to traditional steel pipes and polyvinyl chloride drinking water pipes, but ordinary PE pipes cannot.

Supplier

Luoyang Datang Energy Tech Co.Ltd is a leading Chinese manufacturer specializing in high-quality plastic pipes and fittings. Equipped with state-of-the-art automated production lines and supported by a team of 200 professionals, we offer an extensive product line comprising over 150 types of plastic pipes and fittings designed for water supply and drainage systems, gas transmission, and floor heating systems. Our main products include PVC Pipes and Fittings, PE (HDPE) Pipes and Fittings, PPR Pipes and Fittings, and PEX Floor Heating Pipes.