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What are steel pipes

What are steel pipes

Steel Pipes are necessary materials for construction projects, such as water supply pipes, drainage pipes, gas pipes, heating pipes, wire ducts, rainwater pipes, etc. With the development of science and technology, the pipes used for home decoration have also experienced the development process of ordinary cast iron pipe → cement pipe → (reinforced concrete pipe, asbestos cement pipe) → nodular cast iron pipe, galvanized steel pipe → plastic pipe and aluminum-plastic composite pipe.

  • (1) Water supply pipes: galvanized steel pipe, stainless steel pipe, plastic coated steel pipe, copper pipe, aluminum plastic composite pipe, ABS plastic pipe, polyethylene pipe, polypropylene pipe, etc.
  • (2) Drainage pipes: steel pipe, cast iron pipe, socket prestressed reinforced concrete pipe, socket self stressing reinforced concrete pipe, GPR polyester resin pipe, hobas centrifugal casting glass fiber reinforced polyester resin pipe, polyethylene pipe, PVC plastic pipe, etc.
  • (3) Heating and gas pipes: galvanized steel pipe, CPVC plastic pipe, ABS plastic pipe, polyethylene pipe, etc.
  • (4) Wire sleeve: magnetic tube, aluminum plastic composite tube, etc.
  • (5) Rainwater pipe: there are iron sheet pipe, cast iron pipe, aluminum plastic composite pipe, PE plastic pipe, etc.

20220601120255 95333 - What are steel pipes

Selection of pipes material

PPR pipe is made of polypropylene, which has the advantages of moderate price, heat and corrosion resistance, stable performance, no scaling and service life of up to 50 years. It can be embedded in the wall or embedded in deep wells. However, the construction technology requires high requirements, and special tools and professional knowledge are required for construction to ensure the safety of the system. PVC pipe is a kind of pipe loved, popular and widely used in the world. It has the advantages of good processing performance, low manufacturing cost, insulation and corrosion resistance. It can be used as matching water supply accessories for water supply engineering or sewage discharge of buildings. For HDPE pipe, the material used is a kind of pipe made of highly crystalline and non-polar thermoplastic resin. The surface is milky white, which can resist corrosion to most domestic and industrial chemicals, and has excellent insulation characteristics, which makes it very suitable for electric wire and cable, and still maintains good characteristics at low temperature.

Classification of pipes

By production method

(1) Seamless pipe – hot rolled pipe, cold rolled pipe, cold drawn pipe, extruded pipe and jacking pipe.
(2) Welded pipe.

  • (a) Divided by process – arc welded pipe, resistance welded pipe (high frequency and low frequency), gas welded pipe and furnace welded pipe.
  • (b) Divided by weld – straight welded pipe and spiral welded pipe.

By section shape

  • (1) Simple section steel pipe – circular steel pipe, square steel pipe, oval steel pipe, triangular steel pipe, hexagonal steel pipe, rhombic steel pipe, octagonal steel pipe, semicircular steel pipe, others.
  • (2) Steel pipes with complex section – unequal hexagonal steel pipes, five petal quincunx steel pipes, double convex steel pipes, double concave steel pipes, melon seed steel pipes, conical steel pipes, corrugated steel pipes, watch case steel pipes, etc.

By caliber

According to the diameter classification, it can be divided into large diameter seamless steel pipe and small diameter seamless steel pipe.

By wall thickness

According to the wall thickness, it can be divided into thin-wall steel pipe and thick wall steel pipe.

By purpose

Steel pipe for pipeline, steel pipe for thermal equipment, steel pipe for mechanical industry, steel pipe for petroleum and geological drilling, container steel pipe, steel pipe for chemical industry, steel pipe for special purpose, and others.

  • (1) Pipes for pipeline. Such as seamless pipes for water, gas and steam pipelines, oil transmission pipes and pipes for oil and gas trunk lines. Faucet with pipe for agricultural irrigation and pipe for sprinkler irrigation, etc.
  • (2) Pipes for thermal equipment. Such as boiling water pipe and superheated steam pipe for general boiler, superheated pipe, large smoke pipe, small smoke pipe, arch brick pipe and high temperature and high pressure boiler pipe for locomotive boiler, etc.
  • (3) Pipe for mechanical industry. Such as aviation structural pipe (round pipe, elliptical pipe, flat elliptical pipe), automobile half axle pipe, axle pipe, automobile tractor structural pipe, tractor oil cooler pipe, agricultural machinery square pipe and rectangular pipe, transformer pipe and bearing pipe, etc.
  • (4) Pipe for petroleum geological drilling. Such as: oil drilling pipe, oil drill pipe (Kelly and hexagonal drill pipe), drilling tappet, oil tubing, oil casing and various pipe joints, geological drilling pipe (core pipe, casing, active drill pipe, drilling tappet, hoop and pin joint, etc.).
  • (5) Pipe for chemical industry. Such as: petroleum cracking pipe, pipe for heat exchanger and pipeline of chemical equipment, stainless acid resistant pipe, high-pressure pipe for chemical fertilizer and pipe for conveying chemical medium, etc.
  • (6) Pipes for other departments. Such as: container tubes (tubes for high-pressure gas cylinders and general container tubes), instrument tubes, watch shell tubes, injection needles and tubes for medical devices, etc.

Press connect

According to the connection mode of pipe end, steel pipe can be divided into smooth pipe (pipe end without thread) and threading pipe (pipe end with thread).
The threading pipe is divided into ordinary threading pipe and thickened threading pipe at the pipe end. Thickened threading pipe can also be divided into: externally thickened (with external thread), internally thickened (with internal thread) and internally and externally thickened (with internal and external thread). According to the thread type, the threading pipe can also be divided into ordinary cylindrical or conical thread and special thread.
In addition, according to the needs of users, threading pipes are generally delivered with pipe joints.

Welded steel pipe

Welded steel pipe and galvanized welded steel pipe for low pressure fluid transmission

Welded steel pipe for low-pressure fluid transportation is made of carbon mild steel. It is the most commonly used small-diameter pipe in pipeline engineering. It is suitable for transporting water, gas, steam and other media. According to its surface quality, it is divided into galvanized pipe (commonly known as white iron pipe) and non galvanized pipe (commonly known as black iron pipe). The inner and outer walls coated with a zinc protective layer are about 3% – 6% heavier than those not galvanized. According to the different wall thickness of the pipe, it is divided into three types: thin-walled pipe, ordinary pipe and thickened pipe. Thin wall pipe is not suitable for conveying medium, but can be used as casing.

Straight seam rolled welded steel pipe

Straight seam rolled welded steel pipe can be divided into electric welded steel pipe and straight seam rolled welded steel pipe rolled and welded in blocks with steel plate on site. It can be made into several pipe wall thicknesses.

Spiral seam welded steel pipe

Spiral seam welded steel pipe is divided into automatic submerged arc welded steel pipe and high-frequency welded steel pipe.

  1. Spiral seam automatic submerged arc welded steel pipe is divided into class a pipe and class B pipe according to the pressure of conveying medium. Class a pipes are generally welded with ordinary carbon steel Q235, q235f and ordinary low-alloy structural steel 16Mn, and class B pipes are welded with Q235, q235f, Q195 and other steels, which are used as low-pressure fluid transmission pipes.
  2. Spiral seam high frequency welded steel pipe spiral seam high frequency welded steel pipe has no unified product standard, and is generally made of ordinary carbon steel Q235, q235f and other steels.

Seamless steel pipe

Seamless steel pipe is divided into hot rolled pipe and cold drawn (rolled) pipe according to the manufacturing method. The maximum nominal diameter of cold drawn (rolled) pipe is 200mm, and the maximum nominal diameter of hot rolled pipe is 600mm. In pipeline engineering, hot rolled pipe is often used when the pipe diameter exceeds 57mm, and cold drawn (rolled) pipe is often used when the pipe diameter is less than 57mm. Seamless steel pipes commonly used in pipeline engineering include the following three types:

General seamless steel pipe

The general seamless steel pipe is referred to as seamless steel pipe for short. It is made of ordinary carbon steel, high-quality carbon steel, ordinary low-alloy steel and alloy structural steel. It is used to make liquid transmission pipelines or structures and parts.
Seamless steel pipes are supplied according to outer diameter and wall thickness. There are many wall thicknesses under the same outer diameter, and the pressure range is large. Generally, the length of steel pipe is 3 ~ 12.5m for hot rolled pipe and 1.5 ~ 9m for cold drawn (rolled) pipe.
Seamless steel pipe for low and medium pressure boiler
Seamless steel pipe for low and medium pressure boiler is made of No. 10 and No. 20 high-quality carbon steel with working temperature.

Cast iron pipe

Cast iron pipes are made of pig iron. According to different manufacturing methods, it can be divided into: Sand Mold Centrifugal socket straight pipe, continuous cast iron straight pipe and sand mold iron pipe. According to the different materials used, it can be divided into gray iron pipe, nodular cast iron pipe and high silicon iron pipe. Cast iron pipes are mostly used in water supply, drainage, gas and other pipeline projects.

Water supply cast iron pipe

Sand mold centrifugal cast iron straight pipe
Sand centrifugal cast iron straight pipe is made of gray cast iron, which is suitable for the transportation of pressure fluids such as water and gas.

Continuous cast iron straight pipe

Continuous cast iron straight pipe is a continuous cast gray cast iron pipe, which is suitable for the transportation of pressure fluids such as water and gas.

Drainage cast iron pipe

Ordinary drainage cast iron socket and pipe fittings. The flexible anti-seismic interface drainage cast iron straight pipe adopts rubber ring sealing and bolt fastening, which has good flexibility and scalability under internal water pressure. It can adapt to large axial displacement and transverse deflection, and is suitable for indoor drainage pipes of high-rise buildings, especially in seismic areas.

Non ferrous metal pipe

Aluminum and aluminum alloy tube

Aluminum and aluminum alloy refer to industrial pure aluminum with 98% aluminum and aluminum alloy with copper, magnesium, manganese, zinc, chromium and other alloy elements as the main body. Aluminum and aluminum alloy pipes are made of industrial pure aluminum or aluminum alloy by drawing or extrusion. Aluminum has good acid corrosion resistance.

Copper and copper alloy tubes copper tubes are mainly made of pure copper and phosphorus deoxidized copper, which are called copper tubes or red copper tubes. Brass tubes are made of ordinary brass, lead yellow copper and other brass.
Lead and lead alloy pipe.

Plastic pipe

Plastic pipe is generally made of plastic resin as raw material, stabilizer, lubricant, etc. by extrusion in the pipe making machine. Because of its light weight, corrosion resistance, beautiful appearance, no bad smell, easy processing and convenient construction, it has been more and more widely used in construction engineering. It is mainly used for the piping of tap water supply system, drainage, exhaust and sewage sanitary pipe, underground drainage pipe system, rainwater pipe and threading pipe for wire installation, etc.
Plastic pipes include thermoplastic pipes and thermosetting plastic pipes. The main resins used for thermoplastic pipes include PVC, PE, PP, PS, propylene butadiene styrene resin (ABS), PB, etc; The main resins used in thermosetting plastics include unsaturated polyester resin, epoxy resin, furan resin, phenolic resin, etc. Table 1 lists the characteristics and main uses of these plastic pipes (see Table 1).
Table.1 Comparison of characteristics and main uses of several commonly used plastic pipes


The characteristics of

The connection method

The main purpose

PVC tube

It has good tensile and compressive strength, but its flexibility is not as good as other plastic tubes, excellent corrosion resistance, the price is the cheapest in all kinds of plastic tubes, but it is brittle at low temperature

Bonding, socket ring connection, flange thread connection

Used for water supply and drainage, irrigation, gas supply, exhaust pipe, wire conduit, rain pipe, industrial anticorrosive pipe, etc

CPVC tube

Outstanding heat resistance, thermal deformation temperature is100℃, excellent chemical resistance

Bonding, flange thread connection

The hot water pipe

PE tube

Light weight, good toughness, good low temperature resistance, non-toxic, cheaper, high impact strength, but low compressive and tensile strength

Hot melt welding, flange thread connection

Water pipe, rain pipe, gas pipe, industrial corrosion resistant pipe

PP tube

Good corrosion resistance, good strength, high surface hardness, surface finish, with a certain high temperature resistance

Hot melt welding, flange thread connection

Chemical sewage, seawater, oil and irrigation pipes for indoor concrete floors as heating pipes for heating systems

ABS tube

Excellent corrosion resistance, light weight, high heat resistancePE,PVCBut the price is more expensive

Bonding, flange thread connection

Sanitary plumbing, begging pipe, sewage pipe, underground cable pipe, high anticorrosion industrial pipe, etc

PB tube

Dielectric strength toPEandPPFlexibility is betweenLDPEandHDPEBetween, its outstanding characteristics are creep resistance (cold deformation), repeated winding and continuous, temperature resistance, chemical properties are also very good

Hot melt welding, flange thread connection

Water supply pipe, hot and cold water pipe, gas pipe, underground buried high pipe

GRP tube

Excellent corrosion resistance, light weight, high strength, good designable performance

Socket ring connection, flange connection

Widely used in petrochemical pipeline and large caliber water supply and drainage pipeline

UPVC pipes and fittings for building drainage

Unplasticized polyvinyl chloride (UPVC) pipes and fittings for building drainage are extruded and injection molded in the pipe making machine with PVL resin as the main raw material and special additives.

  • (1) Excellent physical properties. UPVC pipes and fittings are corrosion-resistant, high impact strength, low fluid resistance, no scaling, smooth inner wall, not easy to block, and meet the requirements of flame retardant performance of building materials, aging resistance and long service life. Indoor and buried service life can reach more than 50 years, and outdoor service life can reach 50 years.
  • (2) Light weight, convenient for transportation, storage and installation, conducive to accelerating the project progress and reducing the construction cost.
  • (3) The construction cost is saved. The cost of using UPVC pipes and fittings is lower than that of using cast iron pipe system of the same specification, and it is easy to maintain.

It is applicable to the drainage system in buildings. Considering the chemical resistance and heat resistance of pipes, it can also be used in industrial drainage system. It can be used continuously below 60 ℃ and intermittently below 80 ℃.

UPVC Plastic pipes and fittings for water supply

Unplasticized polyvinyl chloride plastic pipes and fittings for water supply are made by mixing, plasticizing, extrusion or injection with food hygiene grade polyvinyl chloride resin as the main raw material and non-toxic special additives. The product meets the national drinking water hygiene standard and adopts socket bonding, elastic sealing ring, metal variable joint and other connection methods.

  • (1) Excellent physical properties, UPVC water supply pipes and fittings have high impact strength, smooth surface and small fluid resistance. The water delivery capacity is 120% of that of the same type of steel pipes, and it is not easy to scale. The water delivery capacity will not be reduced after long-term use.
  • (2) Corrosion resistance, no rust, no corrosion damage due to the corrosivity and material action of soil and water, and the general service life is more than 50 years.
  • (3) The thermal conductivity is small, and it is not easy to crack in winter.
  • (4) Light weight, convenient transportation, storage and installation, high labor efficiency, which is conducive to accelerating the project progress and reducing the construction cost.

It is mainly used in the indoor water supply system of civil residence to replace the traditional white iron pipe and pipe fittings, and can be used in drainage, sewage discharge, transportation of corrosive fluid and other systems. It can also be used to transport water supply pipes of buildings (overhead or buried) with temperature below 45 ℃.

Composite foamed UPVC pipe

The composite foamed rigid PVC pipe is made of three layers of PVC formula. Through this modified PVC inner and outer skin and honeycomb structure core layer, the composite foamed rigid PVC pipe not only has the characteristics that the traditional PVC solid wall pipe is superior to cast iron and copper pipe, but also has the characteristics that the traditional PVC solid wall pipe, cast iron pipe and steel pipe are incomparable. Composite foamed UPVC pipe is a new type of plastic pipe developed in China in recent years.
The product has the characteristics of light weight, low cost, low fluid resistance, acid and alkali resistance, long service life, high mechanical strength, good sound insulation performance, strong electrical insulation, simple construction, heat and cold resistance, etc.
It is suitable for low pressure water supply pipes, drainage pipes, sewage pipes, indoor air conditioning and ventilation pipes, exhaust pipes, wire and cable protective sleeves, cold and hot fluid transmission pipes, chemical and pharmaceutical industrial pipes in industrial and residential buildings.

UPVC special electrical pipes and joints

It is made of PVC resin as raw material and special additives through plasticization and extrusion.
It has the characteristics of good flame retardant performance, corrosion resistance, climate resistance, light weight, beautiful appearance, low cost, supporting products and convenient construction.
It is applicable to various buildings as casing for indoor and outdoor (exposed and concealed) chlorine installation, which plays the role of beautifying indoor environment, fire prevention, safety, insulation and wire decoration.

Flexible PVC plastic pipe

It is made of polyvinyl chloride resin as raw material, plasticizer, stabilizer and other auxiliary agents.
It has the advantages of light weight, corrosion resistance, good electrical insulation and convenient construction.
It is suitable for electrical casing and fluid delivery pipe. At room temperature, electrical casing can protect wires and cables, and liquid delivery pipe can be used to transport some liquids and gases.

Polyethylene plastic pipe

With polyethylene resin as raw material and a certain amount of additives, it is processed by extrusion.
It has the characteristics of light weight, corrosion resistance, non-toxic, easy bending and convenient construction.
It is divided into high-pressure (low-density) polyethylene and low-pressure (high-density) polyethylene. The former has soft properties and low mechanical strength and melting point; The latter has higher density, higher rigidity, higher mechanical strength and melting point.
It is suitable for industrial and civil residence. It can be used as drinking water pipe, rainwater pipe, gas pipe, industrial corrosion-resistant pipe, conveying liquid, gas, edible medium, etc. it can also be used as medical hose.

Polyethylene bellows

It is made from high density polyethylene resin with a certain amount of additives through plasticization.
It has the characteristics of light weight, corrosion resistance, aging resistance, high product strength, good bending performance and convenient construction and installation.
It is suitable for cable casing, underground cable pipe, agricultural irrigation pipe, ventilation pipe, water delivery pipe, etc.

Acrylonitrile butadiene styrene (ABS) pipe

ABS pipe is made of acrylonitrile butadiene styrene terpolymer by extrusion. ABS for pipes and fittings, in which the minimum content of butadiene is 6%, the minimum content of acrylonitrile is 15%, and the minimum content of styrene or its substitute is 25%.
ABS plastic pipe is light, with high impact strength and surface hardness. It can still maintain toughness, firmness and stiffness in the range of – 40 ℃ ~ 100 ℃. Its corrosion resistance and impact resistance are better than PVC pipe. ABS pipe can keep heat more than copper pipe and brass pipe, has high toughness, and can avoid damage caused by severe cold, weather, loading, unloading and transportation. When subjected to higher yield strain, it can recover to the original size without damage. Therefore, it can replace stainless steel pipe, copper pipe and other pipes.
ABS pipe is applicable to domestic water supply, sewage, ventilation system, irrigation system, submersible pump device, drinking water pipeline, gas distribution pipeline, well sleeve and underground electrical pipeline. It can also be used as industrial pipe device for conveying corrosive saline solution, organic matter containing fluid corrosive agent (such as crude oil and food), pure chemicals or other sensitive products.

Source: China Steel Pipe Manufacturer – Yaang Pipe Industry Co., Limited (

(Yaang Pipe Industry is a leading manufacturer and supplier of nickel alloy and stainless steel products, including Super Duplex Stainless Steel Flanges, Stainless Steel Flanges, Stainless Steel Pipe Fittings, Stainless Steel Pipe. Yaang products are widely used in Shipbuilding, Nuclear power, Marine engineering, Petroleum, Chemical, Mining, Sewage treatment, Natural gas and Pressure vessels and other industries.)

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