What is thin-walled steel pipe

What is thin-walled steel pipe?

steel pipe having a ratio of the outer diameter of the steel pipe to the wall thickness of more than 20 is referred to as a thin-walled steel pipe. Thin-walled steel pipe thin-walled steel pipes are all cold drawn. Among them, carbon steel , low alloy steel, alloy steel thin wall pipe is suitable for general structure and mechanical structural parts; thin wall fluid steel pipe is used for conveying general fluid; stainless steel thin wall pipe is used for chemical, petroleum, light industry, food , mechanical instrument, etc. Industrial heat-resistant containers, conveying pipes and mechanical structural parts.

  • Steel pipe specification method: outer diameter * wall thickness (mm)
  • Steel pipe weight calculation formula: [(outer diameter – wall thickness) * wall thickness] * 0.02466 = kg / m (weight per meter)

Specifications   Classification
Standard   Application
Usage characteristics   How to Weld thin Steel Tube
Thick-walled steel pipes VS thin-walled steel pipes

120214030122 - What is thin-walled steel pipe


Common small diameter thin wall tube specifications
Cold drawn seamless tube 8×1-2 Cold drawn seamless tube 10×1-3
Cold drawn seamless tube 12×1-2 Cold drawn seamless tube 12×1-4
Cold drawn seamless tube 14×1-2.5 Cold drawn seamless tube 14×3-4
Cold drawn seamless tube 16×1-2 Cold drawn seamless tube 16×2.5-4
Cold drawn seamless tube 17×1-2 Cold drawn seamless tube 17×2.5-3
Cold drawn seamless tube 18×1-2 Cold drawn seamless tube 18×2.5-6
Cold drawn seamless pipe 19×1-2 Cold drawn seamless pipe 19×2.5-3
Cold drawn seamless tube 20×1-2 Cold drawn seamless tube 20×2.5-6
Cold drawn seamless tube 21×1-2 Cold drawn seamless tube 21×2.5-3
Cold drawn seamless tube 22×1-2 Cold drawn seamless tube 22×2.5-6
Cold drawn seamless tube 24×2.5-6 Cold drawn seamless tube 25×1-2
Cold drawn seamless tube 25×2.5-6 Cold drawn seamless tube 26×1-2
Cold drawn seamless tube 26×2.5-4 Cold drawn seamless tube 27×2.5-6
Cold drawn seamless tube 28×1-2 Cold drawn seamless tube 28×2.5-6
Cold drawn seamless tube 30×2.5-9 Cold drawn seamless tube 31×1-2
Cold drawn seamless tube 32×1-2 Cold drawn seamless tube 32×2.5-10
Cold drawn seamless pipe 34×1-2 Cold drawn seamless pipe 34×2.5-8
Cold drawn seamless pipe 38×1-2 Cold drawn seamless tube 38×2.5-10
Cold drawn seamless tube 40×2-2.5 Cold drawn seamless tube 40×3-6
Cold drawn seamless tube 42×2-2.5 Cold drawn seamless tube 42×3-6
Cold drawn seamless tube 45×3-10 Cold drawn seamless tube 48×2-2.5 
Cold drawn seamless tube 48×3-6 Cold drawn seamless tube 50×2-2.5
Cold drawn seamless tube 50×3-6 Cold drawn seamless tube 51×2-2.5
Cold drawn seamless tube 51×3-6 Cold drawn seamless tube 54×2-2.5
Cold drawn seamless tube 54×3-6 Cold drawn seamless tube 57×2-2.5
Cold drawn seamless tube 57×3-6 Cold drawn seamless tube 60×3-6
Cold drawn seamless tube 63.5×3-6 Cold drawn seamless pipe 65×3-6
Cold drawn seamless pipe 68×3-6 Cold drawn seamless pipe 70×3-6
Cold drawn seamless tube 76×4-16 Cold drawn seamless tube 83×4-18
Cold drawn seamless tube 89×4-25


Seamless steel tubes are divided into two types: hot rolled and cold rolled (dial) seamless steel tubes.

Hot-rolled seamless steel pipes are divided into general steel pipes, low and medium pressure boiler steel pipes, high pressure boiler steel pipes, alloy steel pipes, stainless steel pipes, petroleum cracking pipes, geological steel pipes and other steel pipes.
Cold-rolled (dial) seamless steel pipe in addition to general steel pipe, low and medium pressure boiler steel pipe, high pressure boiler steel pipe, alloy steel pipe , stainless steel pipe, petroleum cracking pipe, other steel pipes, also includes carbon thin-walled steel pipe, alloy thin-walled steel pipe, Stainless thin-walled steel pipe and special-shaped steel pipe. Theouter diameter of the hot-rolled seamless pipe is generally larger than 32mm, the wall thickness is 2.5-75mm, the diameter of the cold-rolled seamless steel pipe can be 6mm, the wall thickness can be 0.25mm, the outer diameter of the thin-walled pipe can be 5mm, and the wall thickness is less than 0.25mm. Cold rolling is more accurate than hot rolling.

General seamless steel pipe

It is made of 10, 20, 30, 35, 45 and other high-quality carbon steel 16Mn, 5MnV and other low-alloy structural steel or 40Cr, 30CrMnSi, 45Mn2, 40MnB and other alloy steel hot-rolled or cold-rolled. Seamless pipes made of low carbon steel such as 10 and 20 are mainly used for fluid conveying pipes. 45, 40Cr and other medium carbon steel seamless pipes are used to make mechanical parts, such as the force parts of automobiles and tractors. Generally, seamless steel pipes are required to ensure strength and flattening test. The hot rolled steel pipe is delivered in a hot rolled state or a heat treated state; the cold rolling is delivered in a heat treated state.

Seamless steel pipe for low and medium pressure boilers

It is used to manufacture various low and medium pressure boilers, superheated steam pipes, boiling water pipes, water wall pipes and superheated steam pipes for locomotive boilers, large smoke pipes, small smoke pipes and arch brick pipes.Hot-rolled or cold-rolled (dial) seamless steel tubes are made of high-quality carbon structural steel. It is mainly made of steel No. 10 and No. 20. In addition to ensuring chemical composition and mechanical properties, it is required to carry out hydraulic test, crimping, flaring and flattening. Hot rolling is delivered in a hot rolled state, and cold rolled (dial) is delivered in a heat treated state.

High pressure boiler steel pipe

High-quality carbon structural steel, alloy structural steel and stainless steel heat-resistant steel seamless steel pipe used for steam boiler pipes such as high pressure and above. These boiler tubes are often operated under high temperature and high pressure, and pipes are exposed to high temperature smoke. Oxidation and corrosion occur under the action of gas and water vapor. Therefore, the steel pipe is required to have high durability, high oxidation resistance, and good structural stability. The steel grade is: high quality carbon structural steel. 20G, 20MnG, 25MnG; alloy structural steel No. 15MoG, 20MoG, 12CrMoG, 15CrMoG, 12Cr2MoG, 12CrMoVG, 12Cr3MoVSiTiB, etc.; 1Cr18Ni9, 1Cr18Ni11Nb high-pressure boiler tubes commonly used for rust-resistant heat-resistant steels, in addition to ensuring chemical composition and mechanical properties, To do the water pressure test, it is necessary to make a flaring and flattening test. The steel pipe is delivered in a heat treated state. In addition, there are certain requirements for the microstructure, grain size and decarburization layer of the finished steel pipe.

Geological drilling and seamless steel pipe for oil drilling

In order to find out the conditions of underground rock formation, groundwater, oil, natural gas and mineral resources, drilling wells are used. Oil and natural gas mining is inseparable from drilling wells. Seamless steel pipes for oil drilling for geological drilling are the main equipment for drilling, mainly including core outer tubes, core inner tubes, casings and drill pipes. Because the drilling pipe is deep enough to work in a depth of several kilometers, the working conditions are extremely complicated, and the drill pipe is subjected to stress such as tension, pressure, bending, torsion and unbalanced impact load, and is also subject to mud and rock wear. Therefore, the pipe is required. Must have sufficient strength, hardness, wear resistance and impact toughness, steel for steel pipe with “DZ” (geological Chinese pinyin prefix) plus number one for steel yield point, commonly used steel number DZ45 45MnB, 50Mn; 40Mn2, 40Mn2Si of DZ50; 40Mn2Mo, 40MnVB of DZ55; 40MnMoB of DZ60, 27MnMoVB of DZ65. The steel pipes are delivered in a heat treated state.

Petroleum cracking tube

Seamless tubes for furnace tubes, heat exchanger tubes and pipes used in petroleum refineries. It is made of high quality carbon steel (10, 20), alloy steel (12CrMo, 15CrMo), heat resistant steel (12Cr2Mo, 15Cr5Mo), stainless steel (1Cr18Ni9, 1Cr18Ni9Ti). In addition to the chemical composition and various mechanical properties, the steel pipe also guarantees water pressure, flattening, flaring and other tests, as well as surface quality and non-destructive testing. The steel pipe is delivered under heat treatment. Stainless steel pipe: stainless steel pipe with various stainless steel hot-rolled and cold-rolled steel. It is widely used in petroleum, chemical equipment pipelines and stainless steel structural parts for various purposes. In addition to ensuring chemical composition and mechanical properties, it is used as a steel pipe subjected to fluid pressure. To ensure that the water pressure test is qualified. All kinds of special steel pipes should be guaranteed according to the regulations.


  1. Seamless steel pipe for structure: GB8162-2008
  2. Ground seam steel pipe for conveying fluid: GB8163-2008
  3. Seamless steel pipe for boiler: GB3087-2008
  4. High-pressure seamless pipe for boiler: GB5310-2008 (ST45.8-III Type)
  5. High-pressure seamless steel pipe for fertilizer equipment: GB6479-1999
  6. Seamless steel pipe for geological drilling: YB235-70
  7. Seamless steel pipe for oil drilling: YB528-65
  8. Seamless steel pipe for petroleum cracking: GB9948- 88
  9. Special seamless pipe for oil drill collar: YB691-70
  10. Seamless steel pipe for automobile semi-axle: GB3088-1999
  11. Seamless steel pipe for ship: GB5312-1999
  12. Cold drawn cold-rolled precision seamless steel pipe: GB3639 -1999
  13. various alloy tubes 16Mn, 27SiMn, 15CrMo, 35CrMo, 12CrMov, 20G, 40Cr, 12Cr1MoV, 15CrMoc
  14. Other: In addition, there are GB/T17396-1998 (hot rolled seamless steel pipe for hydraulic props), GB3093-1986 (high pressure seamless steel pipe for diesel engine), GB/T3639-1983 (cold drawn or cold rolled precision seamless steel pipe), GB /T3094-1986 (cold drawn seamless steel pipe shaped steel pipe), GB/T8713-1988 (precision inner diameter seamless steel pipe for hydraulic and pneumatic cylinders), GB13296-1991 (stainless steel seamless steel pipe for boilers and heat exchangers), GB/T14975 -1994 (stainless steel seamless steel pipe for structure), GB/T14976-1994 (stainless steel seamless pipe for fluid transportation) GB/T5035-1993 (seamless steel pipe for automobile semi-axle casing), API SPEC5CT-1999 (casing and oil pipe) Specification) and so on.


According to incomplete statistics, there are more than 240 seamless pipe production enterprises in China, and there are more than 250 seamless steel pipe units with an annual production capacity of more than 4.5 million tons. From the caliber, <φ76, accounting for 35%, <φ159-650, accounting for 25%. In terms of varieties, general-purpose pipes are 1.9 million tons, accounting for 54%; oil pipes are 760,000 tons, accounting for 5.7%; hydraulic props and precision pipes are 150,000 tons, accounting for 4.3%; stainless steel pipes, bearing pipes and automobile pipes are 50,000 yuan. Tons, accounting for 1.4%.
The billet is fed into a furnace and heated to a temperature of approximately 1200 degrees Celsius. The fuel is hydrogen or acetylene. Furnace temperature control is a key issue. After the round billet is released, it is subjected to a through-hole punching machine. The more common perforating machine is a conical roller punching machine. This perforating machine has high production efficiency, good product quality, large diameter of perforation and can wear a variety of steel types. After perforation, the round billet is successively rolled, rolled or extruded by three rolls. After extrusion, the tube should be sizing. The sizing machine is rotated at a high speed by a conical drill bit into a steel core to form a steel pipe. The inner diameter of the steel pipe is determined by the outer diameter of the sizing machine drill bit. After the steel pipe has been sized, it enters the cooling tower and is cooled by water spray. After the steel pipe is cooled, it is straightened . After the steel pipe is straightened, it is sent to a metal flaw detector (or water pressure test) by a conveyor belt for internal flaw detection. If there are cracks inside the steel pipe, bubbles and other problems will be detected. After the quality inspection of the steel pipe, it must be carefully selected by hand. After the quality inspection of the steel pipe, the paint is sprayed with the number, specification, production batch number, etc. It is hoisted into the warehouse by a crane.

Usage characteristics of thin-walled galvanized stainless steel tube

In building water distribution system, galvanized steel pipe has been over a hundred years glorious history and a variety of new plastic pipes and composite pipes have developed rapidly, but there are some deficiencies due to varying degrees, far from being able to fully meet the water supply pipe needs of the department and the state of drinking water and water quality requirements. Therefore, the experts predicted: the building water supply pipe will eventually be restored to the era of metal pipe. according to the application of foreign experience, wall stainless steel pipe for pipe is one of the best overall performance.

Domestic thin-walled 316 stainless steel tubes that promote the use of the time is ripe:

First, thin-walled stainless steel tube, the country began production in the late 1990s, the use of today’s pipe-and-coming in the field of newborn family have been widely used in building water supply and drinking water pipeline.
Second, the thin-walled stainless steel tube durable has been recognized by the engineering community, and the parties concerned are to reduce the wall thickness, reducing the price to proceed in order to facilitate further promotion. Especially small diameter stainless steel pipe, the price is not high, supporting the connection method, the pipe reliability and price are the main factors that determine its development. Domestic has been a developer in Sichuan, Guangdong, Zhejiang, Jiangsu and other places independently developed connection technology and pipe fittings, pipe promising.
With the implementation of China’s reform and opening-up policy, the national economy experienced rapid growth, urban housing, public buildings and tourist facilities to build a large number of new requirements on the hot water supply and domestic water supply. Water quality problems, there is growing attention, and are required to improve. Galvanized steel pipe is commonly used pipe because of its easy to corrosion under the influence of the relevant national policies, will gradually exit the stage of history, plastic pipe, composite pipe and copper pipe became the piping system used pipe.
However, in many cases, the stainless steel tube is more advantages, especially the wall thickness of only 0.6 ~ 1.2mm wall stainless steel pipe in high-quality drinking water systems, hot water system and will give top priority to safety, health water supply system, with safe, reliable, environmental health, economic application. Engineering practice at home and abroad has been proven to be one of the best overall performance of water supply system, a new, energy-saving and environment-friendly pipe water supply pipe is also a very competitive, improve water quality, improve people’s living standard will play no comparable to the role.

How to Weld thin Steel Tube?

Welding thin steel exhaust tubing requires patience and the correct equipment to get a sealed weld. The difficult part of welding thin walled steel tubing is maintaining your weld puddle without overheating the connection will result in the puddle melting through the tubing. With a properly set up MIG welder and a little practice, you easily create a sealed weld joint on the thin diameter steel tubing. MIG welders are widely available at rental stores or for purchase at your local welding supply retailer.

erw steel pipe process - What is thin-walled steel pipe

The weld of multiple length shell is then head treated electrically, sized and cut to specified lengths by a flying cut-off machine. The cut pipe is straightened and squared at both ends.
These operations are followed by ultrasonic inspection or hydrostatic testing.

Read the owner’s manual for the welding machine to determine how to change the feeder wheels over to accept the .023 welding wire.

Spool the welder with the .023 solid welding wire after you switch the wire feeder wheels.

Open and close the valve located on top of the bottle of shielding gas to clear dirt and debris from the threaded area.

Turn the threads of the MIG welder gas regulator clockwise to attach the regulator to the bottle of shielding gas. Set the adjustable wrench to fit the regulator nut and lock the nut to seal the connection. Open the valve to send gas to the MIG welder.

Turn on the welding machine and place the grounding clamp on a piece of metal.

Point the tip of the MIG gun at the metal and depress the trigger of the MIG gun. Listen to the sound coming from the weld area between the MIG cup and the grounded piece of metal. Adjust the heat and wire speed settings until you hear a sound similar to eggs frying in a pan.

Place the ends of two pieces of steel exhaust tubing tightly together and ground the steel tubing with the grounding clamp.

Wearing your safety glasses, place the end of the MIG wire protruding from the tip of the MIG gun against the center of the weld joint and depress the MIG guns trigger for 1 second to create a tack weld. Roll the pipe, placing tack welds around the weld joint.

Put on your welding helmet and welding gloves.

Rest the wrist of the hand that you are holding the MIG gun with on a firm flat surface and grasp the tacked pieces of pipe with the other hand.

Align the wire extending from the MIG gun with the weld joint, flick your head forward to lower your welding helmet, and depress the trigger of the MIG gun.

Move the MIG 1/8th of an inch and stop to let the weld puddle build, when the weld puddle reaches around 1/8th of an inch tall, move the MIG gun another 1/8th of an inch. Continue the process, turning the pipe as needed to expose more weld joint until you weld around the entire weld joint and reach the spot where you began welding the joint of the steel tube.

Allow the joint to cool thoroughly before you move the welded tubing.

Difference between thick-walled steel pipes and thin-walled steel pipes

The biggest difference between thick-walled steel pipes and thin-walled steel pipes are the thickness of the steel pipe wall. Generally speaking, thin-walled steel pipes are cold drawing technology.
Thick-walled steel pipes generally use hot rolling technology. If they are distinguished by measurement units, then it is generally considered that the wall thickness/tube diameter is equal to 0.05 is the watershed of thick-walled steel pipes and thin-walled steel pipes, and the wall thickness/pipe diameter is less than 0.05. It is a thin-walled steel pipe, which is larger than a thick-walled steel pipe. In terms of use, thin-walled steel pipes are mostly used on pipes. Thick-walled steel pipes are mostly used for blanks of hollow parts. Used under pressure and on important pipelines.

Source: Network Arrangement – China Steel Pipe Manufacturer – Yaang Pipe Industry Co., Limited (www.steeljrv.com)

(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.)

If you want to have more information about the article or you want to share your opinion with us, contact us at sales@steeljrv.com

Please notice that you might be interested in the other technical articles we’ve published:

  • How to get high quality stainless steel pipes

  • What is the difference between a steel pipe and a steel tube

  • Engineering Specification for Pressure Test of Piping System

  • How To Distinguish Inferior Steel Pipe

  • How to get high quality steel pipes

  • Manufacturing process of cold rolled steel pipe

  • How to get high quality boiler tubes

  • What is thick-walled steel pipe

  • How to get high quality alloy steel pipes

  • How to get high quality pipe fittings

  • How to get high quality heat exchanger tubes

  • The difference between steel tubes and steel pipes


  • Difference between welded steel pipe and seamless steel pipe

  • Characteristics of seamless steel pipes


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