There is a wide variety of materials commonly used in pipeline engineering, which are typically selected based on the conveyed medium (such as water, oil, gas, chemical raw materials), temperature, pressure, and service environment (indoor, outdoor, underground). The following is a detailed classification and description of commonly used pipeline materials:
I. Metallic Pipeline Materials
Metallic pipes are the most widely used materials in industrial and construction fields due to their high strength and excellent resistance to high temperatures and pressures.
Carbon Steel
- Ordinary carbon steel: such as Q235, commonly used for manufacturing water pipelines, gas pipelines, or low-pressure fluid transmission pipes for general purposes.
- High-quality carbon steel: such as Grade 10 and Grade 20 steel (common materials for seamless steel pipes), featuring good plasticity and toughness, widely used for transporting steam, petroleum and petroleum products.
- Characteristics: moderate price, high strength, but poor corrosion resistance; usually requires anti-corrosion treatment (such as galvanizing and painting).
Alloy Steel
- Low-alloy steel: such as 16Mn (Q345), with significantly improved strength by adding a small amount of alloy elements on the basis of carbon steel, commonly used for high-pressure pipelines and boiler pipelines.
- High-alloy steel / Stainless steel: such as 304 (18-8 type) and 316L (molybdenum-bearing, with stronger corrosion resistance).
- Characteristics: 304 stainless steel has excellent corrosion resistance and attractive appearance, widely used in the food industry, medical and health sectors, and water supply for high-rise buildings; 316L is used in more corrosive environments such as chemical engineering and seawater desalination.
Cast Iron
- Gray cast iron: with good castability and shock absorption, commonly used for underground water supply and drainage pipelines.
- Ductile iron pipe (DIP): much higher strength and toughness than gray cast iron, with good corrosion resistance, making it one of the preferred materials for urban water supply trunk pipelines.
Non-ferrous Metals
- Copper and copper alloys: such as pure copper (copper tubes) and brass. With excellent thermal conductivity, corrosion resistance and antibacterial properties, they are commonly used for hot water pipes, air conditioning condensate pipes, gas pipelines and instrument pipelines in buildings.
- Aluminum and aluminum alloys: lightweight and good corrosion resistance (especially to atmospheric corrosion), commonly used for transporting chemical media such as concentrated nitric acid and acetic acid, or as air compressor pipelines.
II. Non-metallic Pipeline Materials
Non-metallic pipes have the advantages of corrosion resistance, light weight, easy installation and good insulation performance, and their application has grown rapidly in recent years.
Plastic Pipes
- PVC (Polyvinyl Chloride)
- UPVC (Unplasticized Polyvinyl Chloride): high strength, corrosion resistance and low cost, widely used for water supply and drainage pipelines and chemical pipelines. However, it has poor heat resistance (generally not exceeding 45℃) and is brittle at low temperatures.
- CPVC (Chlorinated Polyvinyl Chloride): better heat resistance than UPVC, can be used for hot water transportation.
- PE (Polyethylene)
- PE80 / PE100: excellent low-temperature resistance (usable at -60℃), chemical corrosion resistance and good impact resistance. Commonly used for gas pipelines, water supply pipelines (especially underground pipes) and sewage pipes.
- Characteristics: good flexibility, bendable with terrain, and excellent weldability.
- PPR (Random Copolymer Polypropylene)
- Characteristics: hygienic, non-toxic, good heat resistance (resistant to hot water above 95℃), and easy connection (hot-melt connection), making it the mainstream material for cold and hot water pipes in home decoration and buildings.
- ABS (Engineering Plastic): good comprehensive mechanical properties, corrosion resistance and impact resistance, commonly used for chemical pipelines and sewage treatment pipelines.
- PB (Polybutene): known as “gold among plastics”, with extremely high temperature resistance (-20℃ to 110℃) and durability, commonly used for hot water pipes in high-end residences, but at a relatively high price.
Concrete and Reinforced Concrete
- Concrete pipes: commonly used for large-diameter urban drainage and rainwater pipelines.
- Reinforced concrete pipes: higher strength, able to withstand large external pressure, commonly used for underground sewage mains and water transmission pipes.
- Characteristics: low cost, corrosion resistance, long service life, but heavy self-weight and poor seismic performance.
Composite Materials
- Steel-plastic composite pipes: such as plastic-lined steel pipes (with a plastic layer lined on the inner wall of steel pipes) and plastic-coated steel pipes. Combining the strength of steel pipes and the corrosion resistance of plastics, they are commonly used for building water supply and drainage and fire-fighting pipelines.
- FRP pipes (Fiber Reinforced Plastic): made of resin and glass fiber through winding. Lightweight, high-strength and highly corrosion-resistant, they are widely used in chemical engineering, electric power, seawater desalination and other fields.
- Aluminum-plastic composite pipes: with an aluminum layer in the middle and plastic layers inside and outside. Featuring the barrier properties (oxygen resistance) of metal pipes and the corrosion resistance of plastic pipes, they were once used for household water supply and are now gradually replaced by PPR, but still applied in certain specific scenarios.
III. Other Special Materials
- Ceramic pipes: extremely high corrosion resistance and wear resistance, commonly used for transporting corrosive slurries containing particles (such as fly ash transportation in mines and power plants).
- Rubber hoses: high elasticity, commonly used in scenarios requiring bending, vibration or temporary transportation (such as flexible hoses and fire hoses).
Summary and Recommendations
- Home decoration: PPR pipes are preferred for water supply; stainless steel corrugated pipes or copper pipes can be used for gas; PVC pipes are mostly used for drainage.
- Urban water supply / gas supply: ductile iron pipes or PE pipes are mostly used for trunk pipelines.
- Industrial / chemical engineering: stainless steel, alloy steel or FRP pipes are selected according to the corrosiveness of the medium.
