Seamless Pipe

Precision Steel tube

High-accuracy Seamless Tubes For Automotive And Hydraulic Systems
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ASTM Seamless Pipes

High-temperature & Pressure Service
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DIN EN Steel Pipes

High-quality Seamless And Precision Steel Tubes Manufactured To Din & En Standards For Diverse Industrial Uses.
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GB steel pipes

Chinese National Standard Industrial Solutions
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JIS Seamless Pipes

Japanese Industrial Standard Steel
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Seamless Pipes By Applications

High-strength Piping Solutions For Diverse Industries
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Galvanized Seamless Tube

Corrosion-resistant And High-strength Piping Solutions
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Carbon Steel Seamless Pipes

High-strength Seamless Pipes For Boilers And High-pressure Systems
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Multi-Rifled Tube

Enhanced Heat Transfer Seamless Tubes For Boilers And Heat Exchangers
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Superior Strength

% Uniform Structure

0

Max Diameter

mm Available

0

Wall Thickness

mm Maximum

0.25

Min Thickness

mm Precision

What is a Seamless Pipe?

Industrial Materials

What Is a Seamless Pipe?

Seamless pipes, manufactured without welds or seams, offer exceptional strength and reliability for high-pressure and high-temperature applications across various industries.

Seamless steel pipes are produced from solid steel billets that are heated and extruded through hot rolling or cold drawing to form a hollow pipe. This weld-free construction ensures uniformity, strength, and leak-proof performance, making them ideal for demanding environments in oil and gas, petrochemicals, power generation, and construction.

Available in carbon steel, stainless steel, and alloy steel variants, these pipes meet stringent standards such as ASTM A106, A335, API 5L, and DIN 17175. They are designed for fluid and gas transport, structural applications, and specialized uses, providing robust and long-lasting solutions for industrial piping needs.

With their superior strength and versatility, seamless pipes are a preferred choice for reliable piping systems, ensuring safe and efficient performance in critical applications.

Steel Pipe & Tubing - All You Need to Know

Steel Pipe and Tubing may seem similar, sharing many characteristics, but they have important differences in purpose, manufacturing, and application.

Steel Pipe & Tubing Definitions
Type Description Subtypes
Tubing A hollow steel shape intended for structural purposes, made from carbon, stainless, or galvanized steel.
  • Mechanical Tubing: Used in low-stress applications (e.g., fences, kitchens, restaurants, hospitals, solar panels) with wall thicknesses up to 10 gauge.
  • Structural Tubing: For high-stress structural applications (e.g., bridges, buildings, roll cages, underwater platforms) with wall thickness from 3/16" and up, often called Hollow Structural Sections (HSS).
Pipe A hollow structure designed to carry materials (e.g., liquids, gases, solids), with wall thickness described by its Schedule.
  • ERW Pipe: Manufactured using Electric Resistance Welding.
  • Seamless Pipe: Manufactured without a welded seam, typically stronger.

How It's Made

Manufacturing Methods for Steel Pipe & Tubing
Method Description Subtypes
Electric Resistance Welded (ERW) A continuous steel sheet is unwound from a coil, shaped using contoured rollers, and welded by heating the edges to over 2,000°F. The pipe or tubing is then cut to size. N/A
Seamless Made by extruding a steel block or drilling a solid steel bar, then cold drawn through a die to achieve desired diameter and thickness. May be annealed and straightened.
  • Cold Drawn Seamless (CDS): Exhibits precise tolerances and a good surface finish.
  • Hot Finished Seamless (HFS): Has less critical tolerances and a scaly finish, not as strong as CDS.
Drawn over Mandrel (DOM) Starts like ERW, but the flash weld is removed, and the tube is cold drawn over a mandrel for better dimensional tolerances, improved surface finish, and the strongest weld strength. N/A

Pipe Sizes

Pipe size is specified with two non-dimensional numbers: Nominal Pipe Size (NPS) for diameter (based on inches) and Schedule Number (SCH) for wall thickness. Both are required to accurately specify a pipe. NPS is the North American standard for pipe sizes used in high and low pressure/temperature applications. The earlier Iron Pipe Size (IPS) designated approximate inside diameter with a single thickness (STD). In 1927, the American Standards Association introduced NPS, replacing IPS with finer wall thickness steps (SCH 5, 5S, 10, 10S, 20, 30, 40, 40S, 60, 80, 80S, 100, 120, 140, 160, STD, XS, XXS).

Other Pipe and Tubing Terms

Common Pipe and Tubing Terms
Term Description
BPE Black Plain End Pipe
BTC Black Threaded & Coupled
GPE Galvanized Plain End
GTC Galvanized Threaded & Coupled
TOE Threaded One End

Typical Pipe Coatings & Finishes

Pipe Coatings & Finishes
Type Description
Galvanized Covered with a protective zinc coating to prevent rusting, via hot-dip galvanizing or electro-galvanizing.
Uncoated No coating applied.
Black Coated Coated with dark-colored iron-oxide.
Red Primed Red oxide primed, used as a base coat for ferrous metals to provide protection.
Seamless Pipe

Customization of

Seamless Steel Tubes and Rebar Couplers

Both seamless steel tubes and rebar couplers can be customized under requirements of steel grade, size, mechanical property and surface quality.

Test

Mechanical property test of size 36 rebar coupler (with maximum tensile force over 850kN).

Small Batch

We can satisfy customers' needs for small batch orders with customization requirements.

Machining

Cutting, Chamfering, Tapping, and Laser Marking.

Comprehensive Solution

Tailored solutions designed to meet specific product needs, aiming to elevate quality while achieving cost efficiency.

Shape Customization

Thick-walled and shaped seamless steel tubes, customized to customer specifications.

Alloy Steel

Produced using advanced automated heat treatment equipment (temperature-controlled ±2°C) for stable performance.

Types of Seamless Pipes

Comparison of Cold Drawn and Hot Finished Seamless Pipes

What is Cold Drawn Seamless Tubing?

(CDS)

Cold Drawn Seamless

CDS tubing is produced by drawing hot-rolled seamless pipes through a die and over a mandrel at room temperature. This refines the grain structure and improves accuracy and mechanical strength.

Key Features:
  • High strength-to-weight ratio
  • Precise tolerances
  • Smooth surface finish
  • Enhanced mechanical properties
Applications:

Hydraulic cylinders, automotive components, precision mechanical parts

What is Cold Drawn Seamless Tubing?

(HFS)

Hot Finished Seamless

HFS tubing is formed by rolling or extruding steel billets at elevated temperatures. This method produces pipes with consistent properties ideal for structural and industrial use.

Key Features:
  • Robust structural integrity
  • Cost-effective production
  • Suitable for general applications
  • Good mechanical properties
Applications:

Structural supports, general-purpose pipelines, industrial machinery

Technical Specifications

Explore the dimensional ranges and common applications of various seamless pipe types.

Typical dimensional ranges for seamless steel pipe types
Type Outer Diameter Wall Thickness Length Applications
Hot-Rolled Seamless Above 32 mm 2.5 – 200 mm Up to 12 m General industrial, structural
Cold-Rolled Seamless 6 – 650 mm 0.25 – 50 mm Up to 12 m Precision applications
Thin-Walled Pipe 5 – 100 mm Less than 0.25 mm Up to 6 m Instrumentation, automotive
Heavy Wall Pipe 50 – 650 mm 10 – 200 mm Up to 12 m High pressure, structural
Seamless Pipe Specification Chart
DN NB (inch) OD (mm) Nominal Wall Thickness (mm)
SCH10 SCH20 SCH30 STD SCH40 SCH60 XS SCH80 SCH100 SCH120 SCH140 SCH160 XXS
15 1/2" 21.3 2.11 2.41 2.77 2.77 3.73 3.73 4.78 7.47
20 3/4" 26.7 2.11 2.41 2.87 2.87 3.91 3.91 5.56 7.82
25 1" 33.4 2.77 2.90 3.38 3.38 4.55 4.55 6.35 9.09
32 1.1/4" 42.2 2.77 2.97 3.56 3.56 4.85 4.85 6.35 9.70
40 1.1/2" 48.3 2.77 3.18 3.68 3.68 5.08 5.08 7.14 10.15
50 2" 60.3 2.77 3.18 3.91 3.91 5.54 5.54 8.74 11.07
65 2.1/2" 73 3.05 4.78 5.16 5.16 7.01 7.01 9.53 14.02
80 3" 88.9 3.05 4.78 5.49 5.49 7.62 7.62 11.13 15.25
90 3.1/2" 101.6 3.05 4.78 5.74 5.74 8.08 8.08
100 4" 114.3 3.05 4.78 6.02 6.02 8.56 8.56 13.49 17.12
125 5" 141.3 3.4 6.55 6.55 9.53 9.53 12.7 15.88 19.05
150 6" 168.3 3.4 7.11 7.11 10.97 10.97 14.27 18.26 21.95
200 8" 219.1 3.76 6.35 7.04 8.18 8.18 10.31 12.7 12.7 15.09 18.26 20.62 23.01 22.23
250 10" 273 4.19 6.35 7.8 9.27 9.27 12.7 12.7 15.09 18.26 21.44 25.4 28.58 25.4
300 12" 323.8 4.57 6.35 8.38 9.53 10.31 14.27 12.7 17.48 21.44 25.4 28.58 33.32 25.4
350 14" 355.6 6.35 7.92 9.53 9.53 11.13 15.09 12.7 19.05 23.83 27.79 31.75 35.71
400 16" 406.4 6.35 7.92 9.53 9.53 12.7 16.66 12.7 21.44 26.19 30.96 36.53 40.19
450 18" 457.2 6.35 7.92 11.13 9.53 14.27 19.05 12.7 23.83 39.36 34.93 39.67 45.24
500 20" 508 6.35 9.53 12.7 9.53 15.09 20.62 12.7 26.19 32.54 38.1 44.45 50.01
550 22" 558.8 6.35 9.53 12.7 9.53 22.23 12.7 28.58 34.93 41.28 47.63 53.98
600 24" 609.6 6.35 9.53 14.27 9.53 17.48 24.61 12.7 30.96 38.89 46.02 52.37 59.54
650 26" 660.4 7.92 12.7 9.53 12.7
700 28" 711.2 7.92 12.7 15.88 9.53 12.7
750 30" 762 7.92 12.7 15.88 9.53 12.7
800 32" 812.8 7.92 12.7 15.88 9.53 17.48 12.7
850 34" 863.6 7.92 12.7 15.88 9.53 17.48 12.7
900 36" 914.4 7.92 12.7 15.88 9.53 19.05 12.7
Minimum Thickness of Seamless Pipe

Seamless Pipes

Minimum Thickness

Seamless pipes, available in various wall thicknesses, are designed for precise applications, with cold-rolled thin-walled pipes achieving thicknesses as low as 0.25 mm or less.

The outer diameter of hot-rolled seamless pipe is generally greater than 32mm, the wall thickness is 2.5-200mm, the outer diameter of cold-rolled seamless steel pipe can be 6mm, the wall thickness can be 0.25mm, the outer diameter of thin-walled pipe can be 5mm, and the wall thickness is less than 0.25mm, cold rolling

The ability to produce seamless pipes with ultra-thin walls and controlled ovality makes them critical for industries like automotive, hydraulics, and petrochemicals, ensuring reliability and performance.

Permissible Variations in Outside Diameter of Steel Pipes
NPS/ DN/ OD Permissible Variations in Outside Diameter
Over Under
in. mm in. mm
NPS 1/8 to 1½, incl
DN 6 to 40
OD 10.3 to 48.3, mm		 1/64 0.4 1/64 0.4
Over 1½ to 4, incl
DN 40 to 100
OD 48.3 to 114.3, mm 		1/32 0.8 1/32 0.8
Over 4 to 8, incl
DN 100 to 200
OD 114.3 to 219.1, mm		 1/16 1.6 1/32 0.8
Over 8 to 18, incl
DN 200 to 450
OD 219.1 to 457, mm		 3/32 2.4 1/32 0.8
Over 18 to 26, incl
DN 450 to 650
OD 457 to 660, mm		 1/8 3.2 1/32 0.8

According to the production method, seamless tubes are divided into hot - rolled tubes, cold - rolled tubes, cold - drawn tubes, extruded tubes, jacking tubes, etc. The maximum diameter is 650 mm and the minimum diameter is 0.3 mm. Depending on the application, there are thick - walled tubes and thin - walled tubes. Seamless steel tubes are mainly used as petroleum geological drilling tubes, cracking tubes for petrochemical industry, boiler tubes, bearing tubes and high - precision structural steel tubes for automobiles, tractors and aviation. In the plate, Q345B seamless steel pipe belongs to the low - alloy series.

Among the low - alloy materials, this kind of material is the most common. The outside diameter of hot - rolled seamless pipe is usually more than 32mm, the wall thickness is 2.5 - 200mm, the outside diameter of cold - rolled seamless steel pipe can be 6mm, the wall thickness can be 0.25mm, the outside diameter of thin - walled pipe can be 5mm, and the wall thickness is less than 0.25mm, cold rolling has higher dimensional accuracy than hot rolling.

Common Standards for Seamless Pipes

A consolidated overview of international seamless pipe standards, their materials, and applications.

Overview of Seamless Pipe Standards from ASTM, API, JIS, and GB
Standard System Standard Code Material Type Typical Applications
ASTM / ASME
(USA)		 ASTM A53 Carbon Steel General-purpose piping, structural
ASTM A106 Carbon Steel High-temperature service
ASTM A179 Low Carbon Steel Heat exchangers, condensers
ASTM A333 Carbon/Alloy Steel Low-temperature service
ASTM A335 Alloy Steel High-temperature, pressure piping
ASTM A213 / A209 Alloy/Stainless Steel Boilers, superheaters
ASTM A312 Stainless Steel Corrosion-resistant piping
ASTM A519 Carbon/Alloy Steel Mechanical tubing (e.g., SAE 1026)
ASTM A790 Duplex Stainless Steel High-strength, corrosion-resistant service
API
(Oil & Gas)		 API 5L Carbon Steel Oil & gas pipelines
API 5CT Carbon Steel Casing & tubing for wells
JIS
(Japan)		 JIS G3454/G3455/G3456 Carbon Steel Pressure piping service
JIS G3460 Carbon Steel Boilers, heat exchangers
JIS G3429 High-strength Steel High-pressure gas cylinders
GB
(China)		 GB 3087 Carbon Steel Low & medium pressure boilers
GB 5310 Carbon Steel High-pressure boiler pipes
GB/T 8163 Carbon Steel Fluid and structural use
FAQ

A seamless pipe is made from a solid billet pierced and drawn into a tube without welding. This gives it a uniform structure and higher pressure resistance compared to welded pipes.

The process involves heating a billet and rotary piercing it, followed by hot rolling, cold rolling, or cold drawing to achieve diameter and thickness.

Seamless pipes have no weld seam, giving them higher strength (~20% more pressure capacity), uniform thickness, and better corrosion resistance. Welded pipes are cheaper, available in large diameters and lengths, but the seam can be a weak point.

They can be made of carbon steel, alloy steel, and stainless steel, depending on the application requirements.

Common specs include ASTM A106, A53, A333, A335, A213, API 5L, and EN 10216‑2 for carbon, alloy, and stainless seamless pipes.

Used in oil & gas transmission, well casings, boilers, heat exchangers, structural piping, hydraulic cylinders, automotive, aerospace, power plants, chemical industries, and water systems.

Diameters range from ⅛″ to ~26″; wall thickness schedule SCH 10–160. Lengths: 6 m, 12 m or custom; finishes include natural, varnished, black paint, FBE, 3PE, with plastic or iron caps.

Yes.
Due to complex manufacturing, seamless pipes are typically pricier than welded, but offer higher performance and durability.

Yes.
Seamless pipes can substitute welded pipes in most applications, but welded pipes cannot always replace seamless in high-pressure/temperature situations.

Production becomes uneconomical and equipment-limited above ~24–26″ OD, so seamless pipes larger than that are rare or made via special hot-expansion processes.

Industry Applications

Seamless pipes are critical in various industries thanks to their excellent strength, temperature resistance, and structural uniformity. They ensure safe and efficient performance in demanding environments.

Power Generation

Used in steam pipelines, boiler tubes, superheaters, and heat exchangers for high-temperature and high-pressure conditions in power plants.

Oil & Gas Industry

Transports crude oil, natural gas, and petroleum products in pipelines and refinery units, handling high-pressure and corrosion.

Chemical & Petrochemical

Handles chemicals, gases, and hazardous substances in reactors and heat exchangers, ensuring safe processing.

Mechanical & Automotive

Applied in automotive systems and machinery for fluid conveyance and precision components requiring strength and accuracy.

Construction & Structural

Used in structural support, water and sewage systems, and building frameworks for strength and corrosion resistance.

Marine & Shipbuilding

Utilized in hydraulic and engine systems onboard, resisting corrosion in marine environments.

Aerospace & Defense

Employed in aircraft and military equipment for hydraulic systems and structural components.

Food & Pharmaceuticals

Stainless pipes for hygienic transport of food and pharmaceutical products, maintaining sterility.

Mining & Slurry Transport

Designed for transporting slurries and chemicals in mining, withstanding abrasion and harsh conditions.

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