What is a seamless steel pipe

What is a seamless steel pipe?

A seamless steel pipe is a circular pipe having a hollow section and no seams around it. The seamless steel pipe is made of carbon steel, alloy steel, stainless steel ingot or solid tube blank, and then is made by hot rolling, cold rolling or cold drawing. Seamless pipes are considered superior to welded pipes as they are built using monolithic steel billets, with intrinsic mechanical strength, without seam welds.

1 Characteristics 2 Classification 3 Manufacturing process
Material Standard Dimension
Applications Quality testing

Characteristics of seamless steel pipe

Seamless steel pipe for the use of engineering and construction is very widely, it is a hollow steel strip no seams, it is mainly used to transport liquids pipelines, different look and general steel,one of those heavy type steel, it has a strong resistance to corrosion, resistant to general corrosion.
Will not rust, this performance makes seamless steel tubes extend the life, the most important is that it is very clean and no toxins.
Compared with other plastic seamless steel pipe having strong mechanical resistance, impact regardless of how high a temperature is not interested in the use of seamless steel pipe, it is mounted and the other pipe is the same, can replace other piped water and other liquids. 

Characteristics of seamless steel pipe are as follows:

High precision can do small batch production.

  • Smaller diameter.
  • Weldability strong, high compression capability.
  • Steel pipe superior performance, relatively dense metal.
  • Steel Cross area is more complex.
  • High precision cold drawn products, good surface quality.

Classification of Seamless Steel Pipe

According to the manufacturing process, seamless pipe can be divided into hot-rolled seamless steel tubes and cold-drawn seamless steel pipe two kinds. Cold drawn tube is also divided into circular pipe and shaped pipe. 

Hot-rolled seamless steel pipe: 

Hot rolled is relative to the cold-rolled, cold rolling is below the recrystallization temperature of the rolling, and hot rolled is carried out at above the recrystallization temperature of the rolling.

Hot rolled seamless steel pipe - What is a seamless steel pipe


hot rollded seamless steel pipe can damage the cast microstructure of the steel ingot, refinement of the crystal grains of the steel, and eliminate the defects of the microstructure, so that the the steel organization compacting, improve the mechanical properties. This improvement is reflected in the rolling direction, so that the steel is no longer to a certain extent isotropic; pouring the formation of bubbles, cracks, and osteoporosis, under high temperature and pressure can also be welded together.


1 After the hot rolling, the nonmetallic inclusions in the interior of a steel (mainly sulfides and oxides, as well as the silicate) was pressed into a sheet, stratified (laminated) phenomenon appears. The layering of the steel in the thickness direction by the pull performance deteriorated significantly, and may appear in the weld shrinkage interlayer tear. Weld shrinkage induced local strain often reach several times the yield point strain, the strain is much greater than the load caused;

2 Residual stress caused by uneven cooling. The residual stress is the stress of internal self-phase equilibrium in the absence of external force, the hot-rolled steel of various cross-sectional has a residual stress such Usually steel sectional dimension is the greater, the greater the residual stresses. Residual stress is self-phase equilibrium, but the steel members in the performance external force or have a certain influence. Such as deformation, stability, anti-fatigue may adversely.

3 Hot-rolled steel products, poor control of thickness and edge width. We are familiar with the thermal expansion and contraction, even if the beginning of the hot-rolled out are standard length, thickness, or there will be some negative final after cooling, this negative differential edge width wider the increasing thickness of the performance of the more obvious.

So for large steel for steel edge width, thickness, length, angle, and sideline no law requires too precise.

Cold rolled seamless pipes:

Cold rolled seamless pipes are cold drawn or cold rolled precision seamless steel pipes with high accuracy of the dimension and good finish of the surface used for the machinery and hydraulic equipment. The cold rolled process refers to the method adopted to process the steel plates or strips into various types of steel products by cold working processes such as the cold bend and cold drawn processes. Cold rolled seamless pipes not only include general steel pipes, low and medium pressure boiler steel pipes, high pressure boiler steel pipes, alloy steel pipes, stainless steel pipes, petroleum cracking steel pipes, but also include carbon steel pipes with thin walls, alloy steel pipes with thin walls, stainless steel pipes with thin walls and special-shaped steel pipes. The hot rolled seamless pipes usually have outer diameter larger than 32mm and wall thickness between 2.5mm to 75mm; the cold rolled seamless pipes usually have the outer diameter less than 6mm and wall thickness less than 0.25 mm; the thin-wall pipes usually have the outer diameter less than 5mm and wall thickness less than 0.25mm. The cold rolled pipes generally have the high dimensional accuracy than the hot rolled pipes.

Advantages and disadvantages of cold rolled seamless pipes

1. The speed of molding and the productivity are high. The coating will not be damaged. The sections can be made in various shapes so as to adapt to different conditions. Cold rolled processes can make steel have great plastic deformation so as to increase the yield point of steel.
2. Cold rolled processes can destroy the casting structure of steel ingots, refine the grain of steel products and eliminate the defects of microstructure so as to make the structure of steel products compact and improve the mechanical property of steel products. This kind of improvement reflects mainly along the rolling direction, which makes steel products not isotropic bodies any longer to some extent. Bubbles, cracks and shrinkage formed in casting can be repaired under the effects of high temperatures and pressure.
1. The section of cold rolled steel is the open section generally, which has relatively low free torsion stiffness. The steel is twisted easily when it is bent; flexural-torsional buckling showed up easily when steel is pressed. The torsion resistance is relatively poor.
2. The wall of the cold rolled steel pipe is relatively thin. The corners connecting plates are not thickened. The bearing ability of the partial concentrated load is weak.

Seamless steel pipes is divided into the following categories because of different purposes:

seamless steel pipe for structure is mainly used for general structure and mechanical structure. 
Transmission fluid with seamless steel tubes is mainly used for the transmission fluid on pipeline projects and large equipment. 
Low and medium pressure boiler seamless steel pipe is used in manufacturing a variety of structures for low and medium pressure boiler superheated steam pipes, boiling water tube and locomotive boilers, superheated steam pipe, opium pipe, a small smoke pipe and arch brick works of high quality carbon structural steel hot-rolled and cold drawn seamless steel tubes. 
High-pressure boiler seamless steel pipe is used for the manufacture of high and above the pressure water tube boiler to heat the surface with high-quality carbon steel, alloy steel and heat-resistant stainless steel seamless pipe. 
Seamless steel pipe for high pressure chemical fertilizer equipmentsis is applicable to the operating temperature of -40 ~ 400 ℃, working pressure of 10 ~ 30Ma chemical equipment and pipeline quality carbon structural steel and alloy steel seamless steel pipe. 
Petroleum cracking seamless steel pipe is for oil smelter boilers, heat exchangers and their transmission fluid pipe. 
Geological drilling steel pipe is the core drilling tubes for geological department,which to be used by end-use can be divided into the drill pipe, drill collars, core pipe, casing and precipitation tubes. Diamond core drill seamless steel pipe is used for diamond core drilling, core rod, seamless steel pipe casing.

Hot Rolling Seamless Steel Pipe Vs. Cold Rolling Seamless Steel Pipe

Seamless steel pipe can be divided into hot rolling seamless steel pipe and cold rolling seamless steel pipe. Next, Prime Steel Pipe will show you the difference between them.
Cold rolling seamless steel pipe
Cold rolled seamless steel pipe is a seamless steel pipe for high dimensional accuracy and good surface finish. Cold rolled seamless pipe in addition to include the general steel, low and medium pressure boiler tube, high-pressure boiler tubes, alloy steel pipe, stainless steel pipe and oil cracking tube, also includes carbon thin wall steel pipe, alloy thin wall steel tube, thin-walled stainless steel pipe and special-shaped steel tube. The diameter of cold rolled seamless steel pipe is 6mm, wall thickness is 0.25mm, while the diameter of thin-walled tube can be 5mm, wall thickness can less than 0.25mm. The dimensional accuracy of cold rolling is higher than that of hot rolling.
Hot rolling seamless steel pipe
Hot rolling is relative to the cold rolling. Cold rolling carries on rolling below the temperature of recrystallization, and hot rolling is above the recrystallization temperature. Hot rolled seamless steel pipe is generally divided into low, medium, high pressure boiler steel pipe, alloy steel pipe, stainless steel pipe, oil cracking pipe, geological steel pipe and other steel pipe. The outside diameter of hot rolled seamless tube is generally greater than 32mm and the wall thickness of that is 2.5-75mm.

Manufacturing process of seamless steel pipe

The main production process of hot rolled seamless steel pipe:

Tube blank preparation and inspection △→Tube heating→Perforation→Rolling tube→Steel tube reheating→Fixed (reduced) diameter→heat treatment △→finished tube straightening→finishing→inspection △(non-destructive, physicochemical, Taiwan inspection)→Warehousing

Hot rolled seamless steel pipe deformed processes - What is a seamless steel pipe

The main purpose of the perforation process is to become a solid round billet piercing hollow shell. Capillary in the specifications, accuracy and surface quality can not meet the requirements of the finished product, further improvements are needed to deform the metal through. The main purpose of the stretching machine is further reduced sectional view (main compression wall) for a larger axial extension, so that the capillary improved dimensional accuracy, surface quality and organizational performance.

After stretching machine rolled steel pipe shortage collectively need further molding mill in order to achieve the requirements of the finished pipe. Rolled steel due to pass in the method widely used in the production of seamless steel tubes.

So far, due to the method pass rolling steel can be divided into two categories: core pension without rolling rolling (hollow body rolling), and with the mandrel. Sizing machines, reducing mill and stretch reducing mill belonging to the hole without mandrel type continuous rolling mills are generally coffin. Its main purpose is to reduce the diameter of the deformation process or sizing get finished steel, the wall thickness of process control, can make thinning, thickening or nearly unchanged.

All the traditional hole-type rolling machine with mandrel belong to extend machine. The main purpose is to reduce the deformation process perforated capillary wall thickness and outer diameter roll passes in the deformation zone and the mandrel posed, for a larger axial extension. At the same time a certain improvement in the organization, performance, accuracy, surface quality.

Cold drawn seamless steel tubes process:

Round tube → heating → perforation → Heading → annealing → pickling → oiled (copper) → multi-pass cold drawn (cold rolled) → blank tube → heat treatment → straightening →hydrostatic testing (testing) → mark → storage.

Cold drawn seamless steel tube process - What is a seamless steel pipe
The general cold strip mills, volume should go through continuous annealing (CAPL unit) to eliminate cold hardening and rolling stress, or batch annealing reach the mechanical properties of the corresponding standard specifies. Cold rolled steel surface quality, appearance, dimensional accuracy better than hot-rolled plate, and right-rolled thin product thickness is about 0.18mm, so the majority of users favor.
Rolling hard roll can be used as the raw material of the hot-dip galvanizing plant, hot dip galvanizing line set annealing line. Rolling hard roll weight is generally 6 to 13.5 tons, the coil diameter of 610mm.

Heat Treatment of seamless steel pipe

The quality of heat treatment is directly related to subsequent processing quality and eventually affect the performance and life of the parts, heat treatment is the energy consumption of the machinery industry big polluters.

In recent years, with the advancement of science and technology and its application,  heat treatment process for seamless steel pipe is mainly reflected in the following aspects:

(1) Clean the heat treatment
Heat treatment production waste water, waste gas, waste salt, dust, noise and electromagnetic radiation and so impact on the environment caused by pollution. Solve the heat treatment of environmental pollution problems, the implementation of clean heat treatment (or the green heat treatment) is one of the developed countries the direction of heat treatment technology development. To reduce SO2, CO, CO2, dust and cinder emissions, has basically put an end to the use of coal as a fuel, heavy oil use fewer, mostly switch to light oil, natural gas is still the best fuel. The The burning furnace waste heat utilization has reached a high degree of, the burner structure optimization and empty – fuel ratio strictly controlled to ensure that under the premise of reasonable burning, reduce to a minimum the NOX and CO; gas carburizing, carbonitriding alternative salt treatment and vacuum heat treatment technology to reduce waste containing salts and CN-toxic water pollution; using water-soluble synthetic quenching oil instead of part of the quenching oil, using biodegradable vegetable oil instead of part of mineral oil to reduce oil pollution.

(2) precision heat treatment
Precision heat treatment has two meanings: the one hand, according to the requirements of the use of the parts, materials, structure size, physical metallurgy knowledge and state-of-the-art computer simulation and testing technology, to optimize the process parameters to achieve the desired performance or maximize material Another aspect of the potential; fully guarantee the stability of the optimization process to achieve product quality and degree of dispersion is small (or zero), and the heat distortion zero.

(3) energy-saving heat treatment
Scientific production and energy management is the most efficient use of energy has the potential factors, the establishment of a specialized heat treatment plant to ensure full capacity, give full play to the equipment capacity is the choice of the scientific management. Select energy structure in the heat treatment of primary energy; make full use of the waste heat, waste heat; using low-energy, short cycle process instead of a long cycle, energy consumption process.

(4) less non-oxidation heat treatment
Heated to precisely control the carbon potential protective atmosphere heating alternative oxidizing atmosphere, controlled atmosphere heated nitrogen potential, to improve the performance of the parts after heat treatment, heat treatment defects such as decarbonization, cracks, greatly reducing the heat after finishing stay reduced , improve the efficiency of material utilization and machining. Vacuum plus hot gas quenching, vacuum or low pressure carburizing, nitriding, carbon permeation and boronizing can significantly improve the quality and reduce distortion, and increased life expectancy.

Material of seamless steel pipe

Special Alloys

  • MONEL® R-405
  • MONEL® K-500
  • HASTELLOY® C-276
  • INCOLOY® 825
  • INCOLOY® 800H / 800HT®
  • INCONEL® 718
  • MONEL® ALLOY 400
  • ALLOY 20
  • NICKEL 200/201
  • MONEL® R-405
  • MONEL® K-500
  • MONEL® ALLOY 400
  • INCONEL® 718
  • INCOLOY® 825
  • HASTELLOY® C-276
  • INCOLOY® 800H / 800HT®

Duplex Stainless Steel

  • Super Duplex S32760
  • Duplex S31803
  • DUPLEX 2205

Stainless Steel

  • STAINLESS STEEL 316-316l
  • Stainless Steel 304L
  • Stainless Steel 304

Carbon Steel

Material Pipes Fittings Flanges Valves Bolts & Nuts
Carbon Steel A106 Gr A A234 Gr WPA A105 A216 Gr WCB A193 Gr B7
A106 Gr B A234 Gr WPB A105 A216 Gr WCB A194 Gr 2H
A106 Gr C A234 Gr WPC A105 A216 Gr WCB  
Carbon Steel 
Alloy high Temp
A335 Gr P1 A234 Gr WP1 A182 Gr F1 A217 Gr WC1 A193 Gr B7
A335 Gr P11 A234 Gr WP11 A182 Gr F11 A217 Gr WC6 A194 Gr 2H
A335 Gr P12 A234 Gr WP12 A182 Gr F12 A217 Gr WC6  
A335 Gr P22 A234 Gr WP22 A182 Gr F22 A217 Gr WC9  
A335 Gr P5 A234 Gr WP5 A182 Gr F5 A217 Gr C5  
A335 Gr P9 A234 Gr WP9 A182 Gr F9 A217 Gr C12  
Carbon Steel
Alloy low Temp
A333 Gr 6 A420 Gr WPL6 A350 Gr LF2 A352 Gr LCB A320 Gr L7
A333 Gr 3 A420 Gr WPL3 A350 Gr LF3 A352 Gr LC3 A194 Gr 7


  • 10V-2Fe-3Al
  • 6Al-4V
  • 6Al-4V STA
  • 6Al-4V ELI
  • 6Al-2Sn-4Zr-2Mo

Pipes Color Codes

Pipe color coding is important both for logistical and safety considerations. Color codes are, in some cases, applied on pipes and other piping materials (such as pipe fittings, flanges, and valves) to facilitate the identification, in the storage warehouse or on the field during project execution, of components manufactured in different materials. This is the case of complex plants using, at the same time, carbon, alloy, stainless steel piping products. When a piping system conveys fluids of different types, color codes are applied to distinguish the piping components by media.


The table shows the pipe color coding guidelines set by the PFI ES 22 specification. In addition to the colors specified in the table, welded pipes shall show an additional white stripe.

PFI Standard ES-22 Standard: Pipe Color Coding Recommendations
Carbon Steel Pipes
Material Material Garde Band / Strip Color
Carbon Steel, Electric Resistance Welded Pipe A53 Gr. B/API 1 solid white
Carbon Steel, Smls, specified tensile strength under 70,000 psi (483 MPA) A53 Gr. B No Marking
Carbon Steel, killed steel A106 Gr. B 1 solid green
Carbon Steel, specified tensile strength 70,000 psi (483 MPA) and over A106 Gr. C 2 solid green
Carbon Steel, low temperature (impact tested) A333 Gr. 6 1 solid red
High Yield Carbon Steel Pipes
52,000 min. yield API 5L X-52 1 solid yellow, 1 solid green
60,000 min. yield API 5L X-60 1 solid yellow, 1 solid pink
65,000 min. yield API 5L X-65 2 solid yellow
70,000 min. yield API 5L X-70 1 solid yellow, 1 solid orange
Low Alloy Pipes
C-Mo steel A335 Gr. P1 1   solid orange
1 Cr-1/2 Mo Steel A335 Gr. P12 1   solid orange, 1 solid blue
1 1 /4 Cr-1/2 Mo Steel A335 Gr. P11 1   solid yellow
2 1/4 Cr-1 Mo Steel A335 Gr. P22 1 solid blue
5 Cr-1/2 Mo Steel A335 Gr. P5 1 solid blue, 1 solid yellow
9 Cr-1/2 Mo Steel A335 Gr. P9 2 solid orange
Ferritic and Martensitic Pipes and Tubes
Type 405 A268 TP405 1 solid green, 1 solid black
Type 410 A268 TP410 1 solid green, 1 solid red
Austenitic Stainless Steel Pipes
Type 304 A312 TP304 1 solid black
Type 304L A312 TP304L 2 solid black
Type 304H A312 TP304H 1 intermittent black
Type 309 A358 Gr309 1 solid black, 1 solid brown
Type 310 A358Gr310 1 solid green, 1 solid orange
Type 316 A312 TP316 1 solid gray
Type 316L A312 TP316L 2 solid gray
Type 316H A312 TP316H 1 intermittent gray
Type 317 A312 TP317 1 solid brown, 1 solid green
 Type317L A312 TP317L 1 solid brown, 1 solid red
Type 321 A312 TP321 1 solid pink
Type 321 H A312 TP321H 2 solid pink
Type 347 A312 TP347 1 solid brown
Type 347H A312 TP347H 2 solid brown
Nickel-Alloy Pipes
Nickel 200 1 solid black, 1 solid pink
Incoloy 800 1 solid black, 1 solid orange
Incoloy 800H 1   solid gray, 1 solid red
Incoloy 825 1   solid gray, 1 solid blue
Inconel 600 2 solid blue
Inconel 625 1 solid blue, 1 solid pink
Hastelloy Alloy 8-2 1 solid red, 1 solid orange
Hastelloy Alloy C-276 1 solid red, 1 solid blue
Hastelloy Alloy C-22 2 solid red
Hastelloy Alloy G 1 solid red, 1 solid yellow
Carpenter Alloy 20 C 8-3 1 solid black, 1 solid blue
Monel 400 1   solid black, 1 solid yellow

Standard of seamless steel pipe

Available Specification standaard


We can makes and markets cold-drawn and hot rolled seamless steel pipes and cold-drawn special-section seamless pipes which are widely applied in the industries of petrochemical, boiler, automobile, mechanical, construction.


Specification for Casing and Tubing, Eighth Edition, Petroleum and natural gas industries-Steel pipes for use as casing or tubing for wells.

Product name Executive standard Dimension (mm) Steel code/ Steel grade
Casting API 5CT 114~219 x 5.2~22.2 J55, K55, N80, L80, P110
Tubing API 5CT 48.3~114.3 x 3.2~16 J55, K55, N80, L80, H40
Casting API 5L 10.3~1200 x1.0~120 A, B, X42, X46, X52, PSL1 / PSL2


American Society for Testing and Materials(ASTM), American Society of Mechanical Engineers (ASME)

Product name Executive standard Dimension (mm) Steel code/ Steel grade
Black and Hot-dipped Zinc-coated Steel Pipes Seamless ASTM A53 0.3~1200 x 1.0~150 GR.A, GR.B, GR.C
Seamless Carbon Steel for High Temperature Service ASTM A106 10.3~1200 x 1.0~150 GR.B, GR.C
Seamless Cold-drawn Low-Carbon Steel Heat-Exchanger and Condenser Tubes ASTM A179 10.3~426 x 1.0~36 Low Carbon Steel
Seamless Carbon Steel Boiler Tubes for High Pressure ASTM A192 10.3~426 x 1.0~36 Low Carbon Steel
Seamless Cold-drawn Intermediate Alloy Steel Heat-exchanger and Condenser Tubes ASTM A199 10.3~426 x 1.0~36 T5, T22
Seamless Medium-carbon Steel Boiler and Superheater Tubes ASTM A210 10.3~426 x 1.0~36 A1, C
Seamless Ferritic and Austenitic Alloy Steel Boiler, Superheater and Heat-exchanger Tubes ASTM A213 10.3~426 x 1.0~36 T5, T9, T11, T12, T22, T91
Seamless Carbon and Alloy Steel for Mechanical Tubing ASTM A333 1/4″~42″ x SCH20~XXS Gr1, Gr3, Gr6
Seamless Cold-drawn Carbon Steel Feedwater Heater Tubes ASTM A556 10.3~426 x 1.0~36 A2, B2


Germany Safety(GS), Deutsches Institut für Normung(DIN)

Product name Executive standard Dimension (mm) Steel code/ Steel grade
Seamless Steel Tubes for Elevated Temperature DIN 17175 10~762 x 1.0~120 St35.8,St45.8, 10CrMo910, 15Mo3, 13CrMo44, STPL340, STB410, STB510, WB36
Manufacturing pipeline,vessel,equipment,pipe fittings. DIN 1629 13.5~762 x 1.8~120 St37.0, St44.0, St52.0
Seamless steel tubes for pressure purposes EN 10216 4.0~60.0 x 0.5~8
5-7 m manufacturing lenght
P235GH TC1, P235GH TC2, 16Mo3
Seamless precision steel tube applications EN 10305-1 13.5~165.1 x 1.8~4.85 St33.2
Seamless Precision Steel Tube DIN 2391 4.0~60.0 x 0.5~8 St35, St45, St52
Seamless Steel Tubes DIN 2440 13.5~165.1 x 1.8~4.85 St33.2


Japanese Industrial Standards (JIS) specifies the standards used for industrial activities in Japan.

Product name Executive standard Dimension (mm) Steel code/ Steel grade
High pressure and high temperature service JIS G3454/5/6 19.05~114.3 x 2.0~14 JIS G3454(STPG370, STPG410), JIS G3455(STS370, STS410, STS480), JIS G3456(STPT370, STPT410, STPT480)
Tubes used for machinery, automobiles, bicycles, furniture, appliances and other machine parts. JIS G3445 19.05~114.3 x 2.0~14 STKM11A, STKM12(A,B,C), STKM13(A,B,C), STKM14(A,B,C).
Carbon steel/Alloy steel boiler and heat exchanger tubes JIS G3461,2 19.05~114.3 x 2.0~14 G3461(STB340, STB410, STB510)
G3462(STBA22, STBA23)
Seamless steel tubes for high pressure gas cylinder JIS G3429 19.05~114.3 x 2.0~14
Length: max 16000mm
STH11, STH12, STH21, STH22

GB 国标

Product name Executive standard Dimension (mm) Steel code/ Steel grade
Low and medium pressure boiler seamless pipe GB 3087 19.05~114.3 x 2.0~14 10#, 20#
Low-temperature heat exchanger tubes seamless steel pipe GB/T18984 19.05~351 x 2.0~14 06Ni3MoDG, 09DG, 09Mn2VDG, 10MnDG, 16MnDG
High pressure and above pressure steam boiler tubes with high quality carbon structural. GB5310 19.05~114.3 x 2.0~14 20G, 20MnG, 25MnG, 15MoG, 20MoG, 12CrMoG, 15CrMoG(T12/P12), 12CrMoG, 12Cr2MoWVTiB.

Dimension of seamless steel pipe

Stainless Steel Seamless Pipe Size
Seamless Pipe Schedule
Sch. 5S Sch. 10S Sch. 40S Sch. 80S
(mm) (inches) Pipe Wall Thickness and Weight
kg/m mm
kg/m mm
kg/m mm
1/8 10.3 0.405 1.25
0.28 1.73
0.37 2.42
1/4 13.7 0.540 1.66
0.49 2.24
0.63 3.03
3/8 17.2 0.675 1.66
0.63 2.32
0.85 3.20
1/2 21.3 0.840 1.65
0.81 2.11
1.00 2.77
1.27 3.74
3/4 26.7 1.050 1.65
1.02 2.11
1.28 2.87
1.68 3.92
1 33.4 1.315 1.65
1.30 2.77
2.09 3.38
2.50 4.55
1 1/4 42.2 1.660 1.65
1.66 2.77
2.69 3.56
3.39 4.86
1 1/2 48.3 1.900 1.65
1.91 2.77
3.11 3.69
4.06 5.08
2 60.3 2.375 1.65
2.40 2.77
3.93 3.92
5.45 5.54
2 1/2 73.0 2.875 2.11
3.69 3.05
5.26 5.16
8.64 7.01
3 88.9 3.500 2.11
4.52 3.05
6.46 5.49
11.3 7.62
3 1/2 101.6 4.000 2.11
5.18 3.05
7.41 5.74
13.6 8.08
4 114.3 4.500 2.11
5.84 3.05
8.37 6.02
16.1 8.56
5 141.3 5.563 2.77
9.46 3.41
11.6 6.56
21.8 9.53
6 168.3 6.625 2.77
11.3 3.41
13.9 7.12
28.3 10.98
8 219.1 8.625 2.77
14.8 3.76
20.0 8.18
42.5 12.70
10 273.1 10.750 3.41
22.7 4.20
27.8 9.28
60.4 12.70
12 323.9 12.750 3.97
31.3 4.58
36.1 9.53
73.9 12.70

Applications of seamless steel pipe

Seamless steel pipe is most often used in the construction industry for structural or load-bearing purposes. This structural pipe is extremely durable and therefore it is also used in a variety of applications that require heavier wall thicknesses than are available in welded pipe. Seamless steel pipe can be used for a variety of types of applications. Some of the more common uses and applications for our seamless steel pipe include:

  1. Offshore Rigs
  2. Oilfield Equipment
  3. Pipelines
  4. Rolls
  5. Pressure Vessels
  6. Shipbuilding
  7. Machinery Parts
  8. Heavy Construction

Quality testing of seamless steel pipe

Seamless steel pipe quality testing is a very important step, and for its detection method is also very particular to now all three – ultrasonic testing, eddy current testing, magnetic flux leakage testing, specific circumstances are as follows:

The ultrasonic testing

seamless process Ultrasonic inspection of seamless pipes - What is a seamless steel pipe 
Ultrasonic inspection of seamless pipes

For steel quality inspection, ultrasonic testing, including for the purpose of detected defects ultrasonic testing and ultrasound to measure the dimensions for the purpose of measuring. Wider application of the former, automated testing, manually testing; latter application, generally manual measurement.

Non-destructive testing

seamless process Non destructive testing of seamless steel pipe - What is a seamless steel pipe
Non-destructive testing

Nondestructive Testing, shorted for NDT, is a widely-used method in pipeline inspection. It is a process of testing, inspecting and evaluating the quality and characteristics of the material without damaging the pipeline itself or affecting the later regular work of the pipe. In other words, after NDT testing, the part can still be put into practical use. NDT utilizes the changes in heat, sound and magnets caused by abnormal inner structure or flaws to inspect the internal and external defects of the material.

The common inspection methods of NDT are visual testing (VT), ultrasonic testing (UT), radiographic testing (RT), hydrostatic testing. Anson International co, ltd uses ultrasonic testing (UT) and hydrostatic testing to inspect its line pipes.

In order to verify the mechanical properties of seamless steel pipe to meet the requirements of the standard, the test sample of seamless steel pipe mechanical performance should be prepared carefully. Mechanical property test includes tensile strength, yield strength, elongation, impact energy and so on. Process performance test includes flattening test, flaring test, hydrostatic testing, curling trials, cold bend test, perforation test. These test items are based on different standards and different uses of seamless steel tubes.

The magnetic flux leakage testing

The magnetic flux leakage testing is a non-destructive testing technology based on ferromagnetic material magnetic changes. When the ferromagnetic material is magnetized, and generates a leakage magnetic field due to the presence of defects on the workpiece surface, and therefore, through the detection of the magnetic flux leakage can be found in defects in the large caliber Seamless thermal expansion material. Steel pipe magnetic flux leakage testing technology is divided into two kinds of magnetic particle inspection method and magnetic field measurement method. The former is simple, but requires the naked eye to observe the magnetic marks, it is difficult to automate. The latter despite the device complexity, high cost and the operation is difficult, but it is picked up by sensors leakage magnetic field information, and therefore easy to automate testing suitable for the automatic inspection of large quantities of steel pipe. Therefore, under normal circumstances, no special instructions, usually refers to the magnetic field of the magnetic flux leakage testing of steel pipes assay.

Eddy current testing

seamless process ECT 620 Eddy Currentautomatic Test System - What is a seamless steel pipe
ECT-620 Eddy Currentautomatic Test System

Eddy current testing method is more wide range of applications in the industrial field of non-destructive testing methods. It is based on the theory of electromagnetic induction, without any coupling agent can 100% fast automatic detection of the specimen. it is even more powerful tool for the rapid detection of bulk. Therefore, it is even not limited to the large caliber thermal expansion seamless steel pipe, has become a necessary means of various types of steel quality inspection. Automatic eddy current testing method is mainly suitable for quality inspection of steel pipes a little probe testing method and through-probe testing method two.

The former method of using the high-speed rotation of the point probe to detect longitudinal defects in the steel pipe, the detection speed is determined by the quantity of the probe and the speed of rotation, in general, is relatively slow, and the latter through the probe to detect the steel pipe transverse defects, this method is simple, and the testing speed (generally up to 60m/min), Further, since the eddy current flaw detection method is particularly sensitive pair of through holes, the related standards of the main method is to replace the pipe hydrostatic test.

Hardness Testing Methods of Seamless Steel Pipe

Mechanical properties of steel should be taken into consideration when testing its hardness which related to the quality and performance after deformation, stamping, cutting and other processing. Thus, all seamless steel pipes need mechanical property test, the test has two types: tensile test and hardness test.
Tensile test is use a seamless steel pipe sample, and then pull the sample on the machine till it’s broken, therefore can test its tensile strength, yield strength, and elongation. The tensile test is the most common method to test the mechanical property of metal material. As long as the mechanical property is required, all metal material need to have tensile test. Particularly for those metal materials have complicated shapes that are not easy to be tested, the tensile test is the only way to test its mechanical property.
Hardness test is use a indenter and pressed it into the surface of sample pipes slowly, then measure the depth or dimension of the indentation so that can get the hardness. The hardness test is the simplest and the most convenient method to test the mechanical property of certain material. The hardness test is non-destructive, and has similar values in terms of the relationship between hardness and tensile strength. The hardness of material can be converted into tensile strength values which have great practical significance.
Since the tensile test is not easy to undertake, and it’s convenient to converted hardness to strength, therefore, more and more manufactures choose to test hardness of material rather than its strength. As the development of manufacturing technique and testing technology, materials such as seamless steel pipes and stainless steel pipes which cannot test hardness directly in the past, now can test directly. Thus, the hardness test will gradually replace the tensile test.

Pipe Beveling

Pipe beveling is the process where an angle is formed between the edge of the end of a pipe or tube and a plane perpendicular to the surface.

Pipe beveld cut - What is a seamless steel pipe

A standard pipe bevel angle for welding is 37.5 degrees. Other angles and special forms such as J-Bevels can also be produced on the ends of pipe or tube using automatic beveling machines.

What is pipeline beveled end and why use it?

Pipe Beveling - What is a seamless steel pipe

pipeline beveled endBeveled end, to put it simply, is a joint surface with a specific beveled angle. In fact, it is processed prior to the welding of two pieces of line pipes, an angle formed at the edge of the end of the pipe with the help of a beveling machine. Beveling of pipe or tubing is most commonly used to prepare the ends for welding. It can also be used for deburring the cut ends for safety and aesthetic reasons.

Subtract the pipe’s wall thickness from the pipe’s outside diameter. For example, if you had a pipe with a diameter of six inches and a wall thickness of two inches, you would subtract two from six to get four.

Common types of beveled ends and comparison among different types

Beveling ends can be made into various angles, achieving the better welding seam. Common beveled ends for butt joints are I—Type butt joint, single—V beveled end, double—V beveled end and single U—beveled end.

common types of beveled ends - What is a seamless steel pipe
Common types of beveled ends
  • I—type butt joint, also called square butt joint, is a relatively simple joint method for pipes of 1 to 6 mm in thickness. Strictly speaking, it is not a beveled end joint, for it only requires parallel matching the edges of two pieces together without certain angles. It is easy and economic to process, but is not recommended for pipes of thick walls. As for thicker wall pipes, the angle of the bevel ends needs full consideration, trying to use the least filler metal material to provide the desired welding soundness.
  • Single—V beveled end, is the most widely-used butt joint type in pipeline application. It suits pipes with the thickness of 3 to 26 mm. The beveled angle should be approximately 40 to 60°. Single—V beveled end is processed by a beveling machine. Comparatively speaking, it is more costly and needs more filler material than the I—type butt joint, but the joint is much stronger than the square joint. The disadvantage of single-V beveled end is its easy subjection to angular deformation.
  • Double—V beveled end, also called X—beveled end, is developed on the basis of single—V beveled end. It needs double-side welding, so the material needs to be turned over after welded one side and the preparation time is longer than the single-V beveled end. It can be used for pipes of thickness 12 to 60mm. For pipes of same thickness, a double—V beveled end requires less filler metal material, because there are two narrower V-joints compared to one wider single—V beveled end.
  • Single-U beveled end is a one-side welding joint. It requires less filler metal material than double—V beveled end and is less subjective to deformation. However, due to the radian shape, it is more difficult to process than the former methods.

Beveled angle refers to the angle between the two beveled surfaces. Beveled face angle, normally used for single-U type, refers to the angle between the beveled surface and the vertical line to the pipe itself. The root opening refers to the gap between the roots of both pieces before welding, to ensure the roots get complete welding. The root radius for single-U beveled end is to increase the transverse space between the roots, making the welding reach the bottom of the root.

Yaang can apply any type of Bevel to any degree required.

Seamless pipe end beveld cut - What is a seamless steel pipe
Beveling can applied to the face of any size or diameter of pipe

pipe ends - What is a seamless steel pipe

Ends of Pipes

For the ends of pipes are 3 standard versions available.

  • Plain Ends (PE)
  • Threaded Ends (TE)
  • Beveled Ends (BE)

The PE pipes will generally be used for the smaller diameters pipe systems and in combination with Slip On flanges and Socket Weld fittings and flanges.

The TE implementation speaks for itself, this performance will generally used for small diameters pipe systems, and the connections will be made with threaded flanges and threaded fittings.

root face - What is a seamless steel pipe

The BE implementation is applied to all diameters of buttweld flanges or buttweld fittings, and will be directly welded (with a small gap 3-4 mm) to each other or to the pipe. Ends are mostly be beveled to angle 30° (+ 5° / -0°) with a root face of 1.6 mm (± 0.8 mm).

Length of Pipes

Piping lengths from the factory not exactly cut to length but are normally delivered as:

  • Single random length has a length of around 5-7 meter
  • Double random length has a length of around 11-13 meter
  • Shorter and longer lengths are available, but for a calculation, it is wise, to use this standard lengths;
  • other sizes are probably more expensive.

Pipe cutting

ERW cutting - What is a seamless steel pipe

The length of the pipe cut according to the requirement. Cutting tools have a grinding wheel piece cutting machine (also known as toothless saw), hand saw, cutter and other hand tools.

Grinding wheel piece cutting machine: is suitable for cutting metal pipes or metal profiles, especially bulk cutting processing is the most economic. Pipe cutting length you need should be determined before and draw a good cutting line. Pipe cutting machine before cutting jig should be fixed firmly. Machine starts, press the grinding wheel slowly, not slam the rapid or too much pressure, so as not to burst grinding wheel accidents.

saw blade teeth should point to the thrust direction, saw blade to tighten, not wobble. Operation when the pressure pipe clamp fixed on the console (console height was about lm), then firmly push and pull, can one man operation, but also the two with the operation. To prevent heat and maintain lubrication can be made to Jukou drip oil. No matter use mechanical or hand according to the cutting all rong or feathered a cut section level off is smooth. Research may not be in slit fold truncation.

is the use of rollers with a sharp knife, make 3600 the card on the pipe rotation, tighten the top wire while rotating the hob until it gradually into the top pipe cut off. In this way cutting metal pipe, the pipe will tilt tube wall, not only reduces the tube diameter, also make the pipe wall is not smooth, damage to the conductor. Under normal circumstances should not be taken in cutting metal pipes. When used, if necessary, must be cut diameter steel pipe with a round file file level, so that the pipe diameter and the diameter of the same incision.

How to packing the seamless steel pipes?

There are probably hundreds of different methods for packing a pipe, and most of them have merit, but there are two principles that are vital for any method to work prevent rusting and Sea transportation security.

steel strips bunding for fixed pipes - What is a seamless steel pipe

  • Plastic caps plugged at the two sides of pipe ends
  • Should be avoided by the steel strapping and transport damage
  • Bundled signs should be uniform and consistent
  • The same bundle(batch) of steel pipe should be came from the same furnace.
  • The steel pipe has the same furnace number, the same steel grade, the same specifications.

Yaang packing can meet any needs of the customers.

bundle packing seamless pipe - What is a seamless steel pipe
Bundle packing
naked packing seamless pipe - What is a seamless steel pipe
Naked packing
crate packing seamless pipe - What is a seamless steel pipe
Crate packing
protect by wood at both ends - What is a seamless steel pipe
Protect by wood at both ends
packing u bend tubes - What is a seamless steel pipe
Packing the U-bend tubes
packing oil pipes - What is a seamless steel pipe
Protect by the pipe caps

Source: Network Arrangement – China Seamless 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 [email protected]

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

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  • How to get high quality alloy steel pipes

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  • The difference between steel tubes and steel pipes


  • Difference between welded steel pipe and seamless steel pipe

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