Round Seamless Pipe
High-strength round seamless pipe for industrial applications
Corrosion-resistant round seamless pipe for chemical processing
Precision round seamless pipe for hydraulic system components

Round Seamless Pipe

Product Specifications

Product Name: Seamless Pipe、Round Tubing、Seamless Round Pipe

OD: 6mm – 1020mm

WT: 2.0mm~150mm

Length: 5.8m、6m、9m、12m

Material: Q195、Q215、Q235、Q275、Q355、16Mn、12Mn、15MnV、14MnVTiRe、20Cr、40Cr、45Cr、35CrMo、42CrMo、304、304L、316、316L、321、12Cr1MoV、15CrMo、10Cr9Mo1VNb、12Cr2Mo1

Standard: GB/T 8162、GB/T 8163、GB/T 3087、GB/T 5310、GB/T 14976、ASTM A106、ASTM A53、ASTM A312、ASTM A213、ASTM A335、JIS G 3444、JIS G 3454、JIS G 3461、EN 10216-2、EN 10217-1、EN 10217-2

I. What is Round Seamless Pipe?

Round seamless pipes are hollow cylindrical steel materials manufactured through hot rolled seamless steel pipe processes or cold-drawn processes, featuring a completely concentric cross-section and no welds. As the optimal solution for fluid transportation in industrial applications, hot-rolled seamless steel pipes dominate three major application areas: oil and gas pipelines (62%), mechanical manufacturing (21%), and building structures (17%).

According to GB/T 17395-2008 standard, a typical round seamless steel pipe covers an outer diameter of 6-630mm and a wall thickness range of 0.25-50mm. Its unique geometrical advantages are reflected in the following:
A. Optimization of hydrodynamics: round cross-section reduces flow resistance by up to 30-45%.
B. Equalized pressure distribution: uniformity of annular stress distribution is 2-3 times higher than that of profiled tubes.
C. Material utilization: compared to square tubes Saving 8-12% of steel consumption.

II.Core Advantages and Application Scenarios

(1) Excellent Engineering Performance

Round seamless steel pipe has 15-20% higher compressive strength than welded steel pipe, which is especially suitable for:
High-pressure fluid transportation (working pressure up to 30MPa)
Precision machinery transmission shaft (tolerance ±0.1mm)
Extreme temperature environment (-40℃ to 450℃)

(2) Industry Application Mapping
Application Areas and Specifications
Application Area Typical Specifications Standard Material Selection
Oil and Gas Φ219×6mm - Φ630×20mm API SPEC 5CT J55/K55/N80 steel grades
Automotive Manufacturing Φ25×2.5mm - Φ89×5mm GB/T 3639 20Cr/40Cr alloy steel
Boiler Systems Φ57×3.5mm - Φ159×10mm GB 5310 20G/15CrMoG
Hydraulic Equipment Φ38×1.5mm - Φ108×8mm GB/T 8713 ST52/27SiMn
(3) Selection of circular seamless steel pipes

i. Working pressure > 5MPa: In high-pressure environments, seamless steel pipes demonstrate superior stability and strength.
ii. Corrosion rate of the medium > 0.1mm/year: Seamless steel pipes offer higher corrosion resistance and are suitable for corrosive media.
iii. Temperature fluctuations > 100°C/hour: In conditions with frequent temperature changes, seamless steel pipes effectively prevent thermal stress cracks.
iv. Requirement to withstand rotational stress: Seamless steel pipes can better withstand rotational stress, reducing the risk of fatigue failure.
When selecting seamless steel pipes, it is recommended to contact the seamless steel pipe manufacturer to ensure the selection of high-quality products that meet standards, thereby enhancing equipment safety and service life.

III. In-depth analysis of manufacturing process

(1) Hot-rolled seamless steel pipe production process

Billet heated to 1200℃ plastic state
Conical rolls perforated to form hollow billet
Continuous rolling unit to control the wall thickness tolerance ±7.5%
On-line quenching + tempering heat treatment
Advantage: high production efficiency (3-6 meters per minute), suitable for mass production of standard specifications of round seamless steel tubes.

(2) Cold-drawn seamless pipe production process

Pickling to remove surface oxide layer
Phosphating treatment to enhance lubrication
Multiple cold deformation (section shrinkage ≤ 80%)
Bright annealing to eliminate processing stress
Advantages: dimensional accuracy up to IT9, surface roughness Ra ≤ 0.8μm, suitable for high-end applications such as precision hydraulic cylinder barrels.

IV. Standard for round seamless pipes

Comparison of Chinese and International Standards
Chinese Standard Corresponding International Standard Key Parameter Differences
GB/T 8163 ASTM A106 Carbon content upper limit is 0.02% lower
GB 5310 EN 10216-2 Impact energy requirement is 15J higher
API 5CT ISO 11960 Thread tolerance is 30% stricter

V. Inspection of round seamless pipe

i. Material certificate verification: A third-party report must be provided that includes the melting point and heat treatment batch to ensure that the material complies with standards.
ii. Geometric accuracy testing: The ellipticity should not exceed 0.8%D, and the wall thickness deviation should be controlled within ±10%.
iii. Performance Verification: Hydrostatic testing (1.5 times working pressure) and ultrasonic testing must be conducted to ensure no defects.
iv. Surface Quality: The surface must have no scratches or folds deeper than 0.2mm.
To ensure product quality, it is recommended to select a seamless steel pipe factory with certification and experience to provide high-quality seamless steel pipes that meet the above stringent standards.

Range of OD

6mm to 1020mm.
Range of wall thickness

0.25mm to 75mm.
Range of length

3000mm to 12500mm, fixed length is usually 6m, 9m, 12m.
Material

Carbon steel (e.g. 10#, 20#), alloy steel (e.g. Q355B, Q420B), stainless steel (e.g. 304, 316).
Tolerance range

Allowable deviation of outer diameter ±1.5% D or ±0.75mm (take the larger value), allowable deviation of wall thickness ±10%.
Surface treatment

Hot-dip galvanized, pickled, painted and polished.
Pressure level

1.6MPa to 6.4MPa according to material and application.
Execution standard

GB/T 8162-2018 (seamless steel tubes for structure), GB/T 3639-2021 (cold drawn or cold rolled precision seamless steel tubes).
Unit weight

Calculated according to the outer diameter and wall thickness, the theoretical weight per unit length ranges from 0.1kg/m to 100kg/m.
Uses

Widely used in building structures, machinery manufacturing, fluid transportation, petrochemical, machining and other fields.

Specification

外径

壁厚

38

4-5-6-8-10

42

3.5-4-5-6-8-10-12

45

3.5-4-5-6-8-10-12

48

3.5-4-5-6-8-10-12

51

3.5-4-5-6-8-10-12

57

3.5-4-5-6-8-10-12-14

60

3.5-4-5-6-8-10-12-14

63

3.5-4-5-6-8-10-12-14

73

4-5-6-8-10-12-14-16

76

4-5-6-8-10-12-14-16

83

4-5-6-8-10-12-14-16 -18-20

89

4-6-8-10-12-14-16-18-20-22-25

95

4.5-5-6-8-10-12-14-16-18-20-25

102

4.5-5-6-8-10-12-14-16-18-22-25-30

108

4.5-5-6-8-10-12-14-16-18-20-22-25

114

4.5-5-6-8-10-12-14-16-18-22-25

121

4.5-5-6-8-10-12-14-16-18-20

127

4.5-5-6-8-10-12-14-16-18-20

133

4-5-6-8-10-12-14-16-18-20-22-25-28-30-32-35-40

140

6-8-10-12-14-16-18-20-22-25-28-30-32-35-40

152

6-8-10-12-14-16-18-20-22-25-28-30-32-35-40-50

159

4.5-5-6-8-10-12-14-16-18-20-22-25-30-35-38-40-45

168

5-6-8-10-12-14-16-18-20-22-25-28-30-35-38-40-45-50

180

5-6-8-10-12-14-16-18-20-22-25-28-30-32-35-38-40-45-50-55

194

6-8-10-12-14-16-18-20-22-25-28-30-32-35-38-40-42-45-50

203

6-8-10-12-14-16-18-20-22-25-28-30-32-35-38-40-42-45-50-55-60

219

6-7-8-10-12-14-16-18-20-22-25-28-30-32-35-38-40-45-50-55-60

232

14-16-18-20-22-25-28-30-32-35-38-40-42-45-50-55-60

245

8-10-12-14-16-18-20-22-25-28-30-32-35-38-40-42-45-50-55-60

273

6-8-10-12-14-16-18-20-22-25-28-30-32-35-38-40-42-45-50-55-60

299

8-10-12-14-16-18-20-22-25-28-30-32-35-38-40-42-45-50-55-60-65-70-75

325

9-10-11-12-13-14-16-18-20-22-25-28-30-32-35-38-40-42-45-50-55-60-65-70-75

351

10-12-14-16-18-20-22-25-28-30-32-35-38-40-42-45-50-55-60-65-70-75

356

8-10-12-14-16-18-20-22-25-28-30-32-35-38-40-42-45-50-55-60-65-70-75-80

377

8-10-12-14-16-18-20-22-25-28-30-32-35-38-40-42-45-50-55-60-65-70-75-80

402

12-14-16-18-20-22-25-28-30-32-35-38-40-42-45-50-55-60-65-70-75-80

426

8-10-12-14-16-18-20-22-25-28-30-32-35-38-40-42-45-50-55-60-65-70-75-80

480

10-12-14-16-18-20-22-25-28-30-32-35-38-40-42-45-50-55-60-65-70-75-80

508

10-12-14-16-18-20-22-25-28-30-32-35-38-40-45-50-55-60-65-70

530

12-14-16-18-20-22-25-28-30-32-35-38-40-45-50-55-60-65-70

610

30-35-40-45-50-55-60-65-70-75-80

630

30-35-38-40-45-50-55-60-65-70-75-80

Standard

Standard Country Purpose
ASTM A53 USA Low-pressure fluid transmission
ASTM A106 USA High-temperature and high-pressure fluid transmission
ASTM A333 USA For use in low-temperature environments
ASTM A312 USA Stainless steel pipe for corrosive environments
EN 10216-1 Europe High-temperature and high-pressure piping
EN 10217 Europe Welded steel pipe, widely used in construction and pressure vessels
EN 10210 Europe Hot-rolled steel pipe for structural and piping applications
EN 10255 Europe General-purpose fluid transmission
GB/T 8163 China Fluid transportation piping
GB/T 17396 China High-pressure boiler tube
GB/T 14975 China Stainless steel pipe for chemical and pharmaceutical industries
GB/T 5310 China High-pressure boiler tube, resistant to high temperature and high pressure
JIS G3452 Japan General fluid transmission
JIS G3454 Japan Boiler tube, high-pressure fluid transmission
JIS G3461 Japan Piping for fertilizer and chemical equipment
JIS G3456 Japan For use in high-temperature boilers and piping
DIN 17175 Germany High-temperature and high-pressure boilers and heat exchangers
DIN 2391 Germany Mechanical processing and structural seamless pipe
GOST 8731-74 Russia Conventional pipeline transmission
GOST 8732-78 Russia High-temperature and high-pressure applications
GOST 10705-80 Russia Low-temperature and medium-temperature pipeline use
KS D 3585 Korea Fluid and gas transmission piping
KS D 3517 Korea Boiler tube, high-temperature fluid transmission
IS 1239 India Fluid and gas transmission piping
IS 3589 India High-pressure boiler piping
IS 1742 India Steel pipe for construction and structural use

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