Munurinn á PE rörum og HDPE rörum

PE rör polyethylene-pipe are made of polyethylene plastic. Sem grunngerð plasts, Pólýetýlen hefur framúrskarandi viðnám gegn flestum heimilis- og iðnaðarefnum. 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 rör).

ég. 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. Þess vegna, 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. Hins vegar, 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. Háþéttni pólýetýlen (HDPE for short)

Háþéttni pólýetýlen (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. Þess vegna, 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.

Þess vegna, 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:

1. 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 rör).
2. 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, ryðfríu stáli, bronze, o.s.frv.). The wear resistance of ordinary PE is only one-tenth that of HDPE.
3. Different applications: General PE pipes (medium-density polyethylene pipes) are suitable for transporting gaseous artificial gas, jarðgas, and liquefied petroleum gas, while low-density polyethylene pipes are used as soft pipes. HDPE rör (háþéttni pólýetýlen rör) 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, áveitu, 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.

Comparison of HDPE and LDPE molecular structure showing side chain density and crystallinity differences

IV. Other Key Differences Between HDPE Pipes and Ordinary PE Pipes

4. Different Corrosion Resistance and Chemical Resistance

HDPE pipes offer excellent chemical corrosion resistance, capable of withstanding most acids, basa, and salt solutions. They also possess natural immunity to microbial attack and electrochemical corrosion in soil. Aftur á móti, ordinary PE pipes (especially LDPE pipes) have significantly weaker permeation resistance and chemical resistance due to their lower crystallinity and looser molecular structure. When conveying corrosive media or buried in contaminated soil, the service life of HDPE pipes can be 2-3 times longer than that of ordinary PE pipes.

5. Different Slow Crack Growth Resistance

HDPE pipes have significantly superior slow crack growth (SCG) resistance compared to ordinary PE pipes. This is due to the highly regular molecular chains and high crystallinity of HDPE, which make it less prone to micro-crack formation and propagation under long-term static pressure loads. This characteristic is particularly important for buried gas and water supply pipelines—systems that continuously bear internal pressure, ground loads, and soil displacement stresses over a 50-year service life. The SCG performance of HDPE pipes is several times higher than that of ordinary PE pipes, making it a key indicator for ensuring long-term safe operation.

6. Different Low-Temperature Impact Resistance

HDPE pipes have a lower brittle transition temperature (typically below -60°C), making them more reliable for winter construction and operation in cold regions. While LDPE pipes are flexible, they tend to become hard and brittle at low temperatures; MDPE pipes fall between the two in terms of low-temperature performance. For outdoor buried pipeline projects in northern China and alpine regions, HDPE pipes are the more robust choice.

7. Different Long-Term Hydrostatic Strength

According to standards such as ISO 4427 and GB/T 15558, the long-term hydrostatic strength (MRS rating) of HDPE pipes at 20°C with a 50-year service life is typically PE80 or PE100 grade, while ordinary PE pipes (such as PE63) have significantly lower MRS ratings. This means that under the same wall thickness and diameter conditions, HDPE pipes can withstand higher safe operating pressures—the allowable stress of PE100 pipes is approximately 1.6 times that of PE63 pipes.

8. Different Rapid Crack Propagation Resistance

In high-risk applications such as gas transmission, once a crack occurs in the pipeline, it must be able to stop rapidly to prevent catastrophic consequences. HDPE rör (especially PE100 grade) exhibit excellent rapid crack propagation (RCP) resistance, with critical pressure values significantly higher than ordinary PE pipes across a wide temperature range of -20°C to +20°C. This characteristic makes HDPE pipes the preferred material for medium and high-pressure urban gas pipeline networks.

9. Different Recycling Value

The scrap material and waste pipes generated during HDPE pipe production have high recycling value. Due to the stable molecular structure and low impurity content of HDPE, after cleaning, crushing, and re-pelletizing, it can still be used as high-quality raw material for producing non-pressure pipes or plastic products. Aftur á móti, LDPE and some MDPE grades, which contain more additives and branched structures, experience greater performance degradation after recycling, resulting in relatively lower reuse value.

HDPE pipe versus ordinary PE pipe chemical corrosion resistance comparison in acid and alkali solutions

V. How to Choose Between PE Pipes and HDPE Pipes Based on Project Requirements

1. Pressure Piping Systems → HDPE Pipes Are the First Choice

For piping systems that must withstand internal pressure—including municipal water supply networks, gas transmission pipelines, fire protection water supply pipes, and industrial process pipes—HDPE pipes are a proven and reliable choice. PE100 grade materials can meet maximum working pressure requirements of up to 16 bar (1.6MPa), whereas ordinary PE pipes are typically only suitable for low-pressure or non-pressure systems.

2. Non-Pressure Piping Systems → PE Pipes (LDPE/MDPE) Can Meet Requirements

For applications that do not require pressure-bearing capacity—such as drainage pipes, irrigation hoses, cable conduit pipes, and ventilation ducts—LDPE or MDPE pipes can meet performance requirements while offering better cost advantages. The flexibility of LDPE pipes makes them particularly suitable for installations requiring bending and routing around obstacles.

3. Extreme Temperature Environments → HDPE Pipes Offer Greater Advantages

In alpine regions (where winter temperatures drop below -40°C) or when conveying high-temperature media (long-term operating temperatures exceeding 40°C), the wide temperature-range adaptability of HDPE pipes makes them a safer and more durable choice.

4. Large-Diameter Long-Distance Pipelines → HDPE Pipes Offer Lower Overall Cost

Although the unit weight price of HDPE pipes is higher than ordinary PE pipes, their higher strength grade allows for thinner wall thickness under the same pressure requirements, thereby reducing material consumption. Auk þess, HDPE pipes can be joined using butt fusion welding, achieving seamless pipe connections that significantly reduce the number of fittings required, lower leakage risks, and decrease construction costs. In large-diameter long-distance projects, the total engineering cost of HDPE pipes is often lower than that of ordinary PE pipes.

5. Temporary or Short-Term Projects → Ordinary PE Pipes Are the Economical Choice

For projects with short construction periods and low service life requirements (such as temporary construction water supply or seasonal agricultural irrigation), ordinary PE pipes can meet basic functional requirements while significantly reducing initial investment.

Selection Summary

HDPE pipe applications in pressure piping systems including municipal water supply gas transmission fire protection and industrial process

Birgir

Luoyang Datang Energy Tech Co.Ltd er leiðandi kínverskur framleiðandi sem sérhæfir sig í hágæða plaströrum og festingum. Útbúinn með nýjustu sjálfvirkum framleiðslulínum og studd af teymi af 200 fagfólk, við bjóðum upp á umfangsmikla vörulínu sem samanstendur af yfir 150 gerðir af plaströrum og festingum sem eru hannaðar fyrir vatnsveitu- og frárennsliskerfi, gasflutningur, og gólfhitakerfi. Helstu vörur okkar eru PVC rör og festingar, PE (HDPE) Lagnir og festingar, PPR rör og festingar, og PEX gólfhitarör.