HDPE pipe and fitting,PVC pipe and fitting

HDPE (high-density polyethylene) pipe hot melt welding is a permanent connection method that melts the end of the pipe by heating and then applies pressure to fuse it. This technology can form a joint with the same strength as the pipe itself, ensuring the sealing and durability of the pipeline system.

Main advantages

1. High strength: The weld strength is close to that of the parent material

2. No leakage: integrated connection to avoid interface leakage

3. Corrosion resistance: No additional sealing material is required

4. Long life: Synchronous aging with HDPE pipe (more than 50 years)

 

Classification of hot melt welding methods

(1) Butt hot melt welding (Butt Fusion)

Applicable pipe diameter: generally ≥90mm

Process flow:

End milling - use a milling cutter to ensure that the pipe end is flat and vertical

Heating plate heating - heating to 210±10°C (depending on the material)

Endothermic stage - maintain pressure to form a molten flange at the pipe end

Switch plate removal - quickly remove the heating plate

Welding pressurization - dock within the specified time and cool under pressure

Key parameters:

Step	Pressure (bar)	Time
Heating	0.15~0.3	Adjust based on wall thickness
Soaking	Maintain	Wall thickness (mm) × 10 (seconds)
Cooling	Natural cooling	≥ Wall thickness (minutes)

 

(2) Electrofusion

Applicable scenarios: small diameter or complex locations

Features:

Use pipe fittings with built-in heating wire

Heat after power is turned on to fuse the materials

Operation points:

Scrape off the oxide layer (use a special scraper)

Mark the insertion depth

Power on for heating (voltage/time according to the manufacturer"s instructions)

Natural cooling (forced cooling is prohibited)

 

Key points for welding quality control

(1) Pre-welding inspection

Material verification: Confirm that the pipe/fitting is the same grade PE100 or PE80

Environmental requirements:

Ambient temperature > -5? (a shed needs to be built for insulation in cold weather)

Relative humidity < 90%

Wind barriers need to be set up in windy weather

(2) Process control

Temperature monitoring: The surface temperature of the heating plate needs to be calibrated with an infrared thermometer

Flange shape: A qualified flange should be "double-peaked" with uniform height (reference value: wall thickness × 0.3)

Welding parameters: Strictly follow the requirements of the process card and do not adjust at will

(3) Post-weld inspection

Appearance inspection:

Flanged edges are symmetrical and free of pores

No traces of false welds or carbonization

Destructive test (sampling):

Tensile test (strength ≥ 80% of parent material)

Bending test (no delamination or cracking)

 

Mastering the standardized HDPE hot-melt welding technology is the core of ensuring the quality of pipeline projects.

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HDPE pipes (high-density polyethylene pipes) are widely used in cold and extreme climate regions due to their excellent low-temperature performance, and have become the preferred material for infrastructure construction in many countries. The following is a comprehensive interpretation of this trend:

Why HDPE pipes have more advantages in the global low-temperature market

1. Low-temperature brittleness is better than other materials

The low-temperature brittle point of HDPE pipes can reach -70°C, which is more adaptable to extremely cold climates than PVC (-15°C) and metal pipes (which are prone to shrinkage or freezing due to low temperatures).

In extremely cold regions such as Canada, Russia, and Nordic countries, HDPE pipes perform stably in urban water supply, sewage, and natural gas transmission systems.

2. Widely used in cold regions around the world

North American market (such as Alaska, Canada): HDPE pipes are widely used in municipal water supply, oil and gas transmission, and mining drainage systems because they can maintain flexibility and sealing in extremely cold environments.

Northern Europe and Russia: In Norway, Sweden, Finland, and Russia, HDPE pipes are used in urban central heating pipe networks (external protective pipes), sewage treatment systems, and road ice melting and drainage.

Antarctic Research Station: HDPE pipes are also used in the water supply and drainage systems of polar research stations. They are one of the few plastic materials that can maintain performance below -40°C.

3. Convenient transportation and construction

HDPE pipes are light and flexible, suitable for long-distance transportation and reel laying, and are particularly suitable for rapid deployment in northern high-altitude cold areas.

Hot-melt connection or electric-melt welding can still be performed at low temperatures, and the installation process is not easily affected by temperature, which is more advantageous than metal welding or PVC bonding.

4. Energy-saving and environmental protection advantages

HDPE is a recyclable plastic with high recognition of international environmental standards.

In water supply and other systems, its inner wall is smooth, energy consumption is low, and thermal insulation is good, which reduces transportation energy consumption in cold areas.

5. Trend of replacing metal pipes

Globally, HDPE pipes are gradually replacing galvanized steel pipes and ductile iron pipes, especially in municipal projects in low-temperature areas.

Because metal pipes are prone to cracking due to frost heave, water hammer and corrosion in cold environments, many countries have made HDPE a standard configuration for new projects.

 

In the global low temperature environment, HDPE pipes have become the first choice for water supply, sewage discharge, and energy transportation systems in cold countries and regions due to their advantages such as low temperature resistance, flexibility and impact resistance, easy construction, environmental protection and energy saving.

Official website: www.phtopindustry.com | www.phpipes.com
Contact us: Email:inquiry@phtopindustry.com | Whatsapp:+86 15093100892
Company address: Room 802, 8th Floor, Building 5, Jinyin Modern City, Jinshui District, Zhengzhou City, Henan Province, China

 

 

HDPE pipe and PVC pipe are two widely used plastic pipe materials, which have significant differences in performance, application scenarios and costs. The following is a comparative analysis and summary of applicable scenarios:

 

Raw materials and basic characteristics

HDPE pipe (high-density polyethylene)

Raw materials: polyethylene, with high toughness (elongation at break>800%), strong shock resistance, and chemical corrosion resistance (not resistant to strong oxidizing acids).

Features: low temperature resistance (-70?~40?), better wear resistance than steel pipe, smooth inner wall to reduce head loss, good hygienic performance (no heavy metals).

PVC pipe (polyvinyl chloride)

Raw materials: polyvinyl chloride, with high strength, flame retardancy (V0 grade), weather resistance, but easy to crack at low temperature (-5?~40?).

Features: acid and alkali corrosion resistance (not resistant to concentrated oxidizing acids), good electrical insulation, low cost, but adhesive connection may affect water quality.

 

Key performance comparison

Performance	HDPE Pipe	PVC Pipe
Temperature Resistance	-70? to 65? (suitable for extreme cold environments)	-5? to 40? (brittle at low temperatures)
Pressure Resistance	Lower (PE100 design stress: 8 MPa)	Higher (PVC-U design stress: 10–12.5 MPa)
Connection Method	Hot-melt/Electrofusion (high joint strength)	Adhesive bonding (may contain toxic substances)
Noise Insulation	Excellent (<37 dB at night)	Poor (>62 dB)
Service Life	Over 50 years	20–50 years (adhesive joints prone to aging)
Cost	Higher (but shorter construction time)	Lower (material cost savings of 30%–40%)

 

Best application scenarios

Advantages of HDPE pipes

Municipal engineering: large diameter drainage pipes (such as Saudi Arabia"s 6,600-meter submarine pipeline project).

Building drainage: single-riser system for high-rise buildings (flow rate 13L/s, space saving).

Agricultural irrigation: soil corrosion resistance, flexible and adaptable to terrain.

Industrial field: chemical fluid transportation (corrosion resistance).

Advantages of PVC pipes

Building drainage: indoor drainage (bathroom, kitchen), low cost and easy installation.

Power communication: wire protection sleeve (flame retardant V0 grade).

Municipal drainage: small and medium diameter pipes (maximum 630mm).

Food/pharmaceuticals: wastewater treatment with high antibacterial requirements.

 

Selection suggestions

Preferentially choose HDPE pipes: scenarios that require low temperature resistance, high flow, and long life (such as municipal engineering, chemical transportation).

Preferentially choose PVC pipes: limited budget, flame retardant/insulation or small and medium-sized drainage projects (such as home decoration, power protection).

The two materials have their own emphasis, and the actual selection needs to be combined with specific needs (such as ambient temperature, pressure, budget, etc.).

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HDPE (high-density polyethylene) pipes have become an ideal substitute for traditional metal pipes in the field of gas transportation due to their excellent performance and safety. The following are the main advantages of HDPE gas pipes and related safety standards:

Advantages of HDPE gas pipes

1. Excellent corrosion resistance

HDPE is an inert material that can withstand corrosion from a variety of chemical media, including natural gas, liquefied petroleum gas (LPG) and liquid hydrocarbons in manufactured coal gas, and will not undergo electrochemical corrosion or rust.

2. High toughness and impact resistance

The low-temperature embrittlement temperature is as low as -60°C, and it can be used safely in extreme climates. It has strong seismic resistance and adapts to uneven foundation settlement.

3. Reliable connection method

Adopting hot-melt butt or electric fusion connection, the joint strength is higher than the pipe body itself, eliminating the risk of leakage.

4. Long life and aging resistance

Contains 2-2.5% carbon black, is resistant to ultraviolet radiation, and has a service life of more than 50 years.

5. Convenient and economical construction

Light weight, can be transported in coils, supports trenchless technology (such as jacking, directional drilling), and reduces installation costs.

6. Wear resistance and low flow resistance

The wear resistance is 4 times that of steel pipes, the inner wall is smooth (Manning coefficient 0.009), and the energy consumption of gas transmission is reduced.

7. Environmental protection and safety

The material is non-toxic, recyclable, and meets green environmental protection requirements.

 

Safety standards for HDPE gas pipes

1. International and national standards

GB 15558.1-2015: China"s gas pipe standard, covering PE80 and PE100 materials, and specifies series such as SDR11 (0.4MPa) and SDR17.6 (0.2MPa).

ISO 4437: International standard that specifies the chemical resistance and long-term performance of PE pipes in gas transportation.

2. Color identification

The pipe is usually black with yellow stripes to ensure eye-catching identification.

3. Construction specifications

Specialized hot melt/electric melt equipment must be used to ensure that the interface is defect-free; a sand layer must be laid to protect the pipeline during backfilling.

4. Pressure level

SDR11 is suitable for gas containing liquid hydrocarbons (such as LPG), and SDR17.6 is suitable for low-pressure natural gas.

5. Quality control

Production must pass ISO9001 certification, and some companies use high-quality raw materials such as Borealis to ensure resistance to slow crack growth (SCG) and rapid crack propagation (RCP).

 

Application areas

HDPE gas pipes are widely used in:

Natural gas transmission and distribution

Liquefied petroleum gas (LPG) transmission

Artificial gas pipelines

Industrial gas supply.

HDPE pipes are gradually replacing traditional steel pipes and cast iron pipes with their corrosion resistance, high safety and long life, becoming the preferred material for modern gas transmission systems.

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HDPE (high-density polyethylene) pipes play a vital role in sponge city construction. Their excellent physical properties, environmental protection characteristics and convenient construction make them the core materials for modern urban drainage, rainwater management and ecological restoration. The following is an analysis of the core role of HDPE pipes in sponge city construction and their advantages:

1. Efficient drainage and rainwater management

One of the core goals of sponge cities is to solve the problem of urban waterlogging. HDPE pipes can significantly improve drainage efficiency and reduce the risk of blockage due to their smooth inner wall and low friction coefficient. Compared with traditional concrete pipes, HDPE pipes have stronger water-passing capacity and can deliver larger flows at the same pipe diameter, or use smaller pipe diameters at the same flow rate to reduce project costs.

In addition, HDPE pipes are suitable for rainwater collection and reuse systems, such as:

Permeable pavement and rainwater gardens: HDPE pipes can connect permeable pavements and reservoirs to achieve rapid infiltration and storage of rainwater.

Recycled water reuse system: Some sponge city projects (such as Wuxi, Jiangsu) use HDPE pipes to use treated rainwater for greening irrigation or road washing to reduce water waste.

2. Corrosion resistance and long life

HDPE pipes have excellent chemical corrosion resistance and can resist the erosion of acids, alkalis, salts and industrial wastewater, and are suitable for complex underground environments. Its service life can reach more than 50 years, which is much longer than traditional concrete pipes and cast iron pipes, reducing the economic and environmental burden caused by frequent replacement.

3. Adaptability to foundation settlement and earthquake resistance

Sponge city construction often involves soft soil foundations or areas prone to settlement. The high flexibility and impact resistance of HDPE pipes enable them to adapt to uneven settlement, and even maintain structural integrity under extreme conditions such as earthquakes, avoiding leakage problems caused by pipe rupture.

4. Environmental protection and sustainable development

Recyclable: HDPE materials are recyclable and in line with the green and low-carbon development concept of sponge cities.

Reducing secondary pollution: The inner wall of HDPE pipes is smooth, not easy to scale or breed bacteria, avoiding water pollution, and is particularly suitable for drinking water and rainwater recycling systems.

5. Convenient construction and cost advantages

Lightweight design: HDPE pipes are light in weight, easy to transport and install, and reduce construction difficulty and mechanical requirements.

Flexible connection method: hot melt or electric fusion connection is used to ensure the sealing of the interface and reduce the risk of leakage.

Low comprehensive cost: Although the initial investment may be high, the long-term maintenance cost is low, and the overall economic benefits are better than traditional pipes.

6. Wide application scenarios

The application of HDPE pipes in sponge city construction includes:

Municipal drainage and sewage systems (such as the sponge city pilot in Changde, Hunan).

Industrial wastewater discharge (corrosion resistance makes it suitable for chemical, mining and other fields).

Agricultural irrigation and saline-alkali land improvement (such as fishery water supply and salt brine supply).

Road and tunnel drainage (strong pressure resistance and can withstand vehicle loads).

 

HDPE pipes have become an indispensable key material in sponge city construction due to their corrosion resistance, high flexibility, environmental protection and ease of construction. It not only improves the efficiency of urban drainage systems, but also supports the resource utilization of rainwater, helping cities achieve the ecological goals of "water absorption, water storage, water infiltration and water purification".

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Company address: Room 802, 8th Floor, Building 5, Jinyin Modern City, Jinshui District, Zhengzhou City, Henan Province, China