Seamless Steel Pipe

Seamless Steel Pipe

Seamless Steel Pipe begins as a solid cylindrical hunk of steel called a billet. While still hot, billets are pierced through the center with a mandrel. The next step is rolling and stretching the hollow billet. The billet is precisely rolled and stretched until it meets the length, diameter and wall thickness as specified by the customer order.Seamless steel pipe is a steel pipe made of a whole round steel with holes and no welds on the surface. Seamless steel pipes have hollow sections and are widely used as pipelines for transporting fluids, such as pipelines for transporting oil, natural gas, coal gas, water and certain solid materials.According to the production method, seamless steel pipes can be divided into hot-rolled seamless steel pipes, cold-rolled seamless steel pipes, cold-drawn seamless steel pipes, extruded seamless steel pipes, jacked pipes, etc.


Seamless steel pipe refers to a steel pipe made of a single piece of metal with no seams on the surface.

Seamless steel pipes are mainly used as petroleum geological drilling pipes, cracking pipes for petrochemical industry, boiler pipes, bearing pipes, and high-precision structural steel pipes for automobiles, tractors, and aviation.


Sizes of Seamless Steel Pipe

Out diameter: 1/4"-36"                 
Wall thickness: SCH: SCH10,SCH20,STD,SCH40,SCH60,XS,SCH80,SCH100,SCH120,SCH160,XXS
Length:3m-12m


Types of Seamless Steel Pipe

Hydraulic pipe
Boiler Tube
Fluid Pipe
Fire Pipe
Line Pipe
Structure Tube
Mechanical tube

Standard of Seamless Steel Pipe

ASTM A53 Gr.B __Black and hot-dipped zinc-coated steel pipes welded and seamless
ASTM A106 Gr.B __Seamless carbon steel for high temperature service
ASTM SA179 __Seamless cold-drawn low-carbon steel heat exchanger and condenser tubes
ASTM SA192 __Seamless carbon steel boiler tubes for high pressure
ASTM SA210 __Seamless Medium-carbon boiler and superheater tubes
ASTM A213 __Seamless alloy-steel boiler, superheater, and heat-exchanger tubes
ASTM A333 GR.6 __seamless and welded carbon and alloy steel pipe intended for use at low temperatures.
ASTM A335 P9,P11,T22,T91 __Seamless ferritic alloy-steel pipe for high-temperature service
ASTM A336 __Alloy steel forgings for pressure and high-temperature parts
ASTM SA519 4140/4130 __Seamless carbon for mechanical tubing
API Spec 5CT J55/K55/N80/L80/P110/K55 __Seamless steel pipe for casing
API Spec 5L PSL1/PSL2 Gr.b, X42/46/52/56/65/70 __Seamless steel pipe for line pipe
DIN 17175 __Seamless steel tube for elevated temperture
DN2391 __Cold drawn seamless prevision pipe
DIN 1629 __Seamless circular unalloyed steel tubes subject to special requirements


Tolerance of Seamless Steel Pipe

OD tolerance
For standard pipe, except as provided for thin-wall pipe, the tolerances of diameter shall be in accordance with the following table:
For pipe over 10 inch as special OD tolerance pipe, the OD shall vary within +1% /-1%.
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


Thickness tolerance

The wall thickness at any point shall be within the below tolerance table.
NPS/ DN/ OD Tolerance, % from Nominal
Over Under
NPS 1/8 to 2½, incl, all t/D ratios
DN 6 to 65
OD 10.3 to 73.0, mm
20.0 12.5
NPS 3 to 18, incl, t/D up to 5%
DN 80 to 450
OD 88.9 to 457, mm
22.5 12.5
NPS 3 to 18, incl, t/D > 5%
DN 80 to 450
OD 88.9 to 457, mm
15.0 12.5
NPS 20 and larger, incl, welded, all t/D ratios
DN 500
OD 508
17.5 12.5
NPS 20 and larger, incl, seamless, t/D up to 5%
DN 500
OD 508
22.5 12.5
NPS 20 and larger, incl, seamless, t/D > 5%
DN 500
OD 508
15.0 12.5


Length tolerance

For Seamless and Welded pipe, if definite cut lengths are ordered, the length shall vary within -0mm / +6mm.

Weight tolerance
For pipe NPS 12 (DN300, 323.8mm) and under, the weight shall vary within -3.5% / +10%.
For pipe over NPS 12 (DN300, 323.8mm), the weight shall vary within -5% / +10%.
Pipe of NPS 4 (DN100, 114.3mm) and smaller may be weighed in convenient lots; pipe in sizes larger than NPS 4 shall be weighed separately.

Delivery status of Seamless Steel Pipe

It is divided into hot rolling, cold drawing (rolling), as well as heat treatment, such as normalizing, quenching and tempering, solid solution, and annealing. 

Mechanical properties of Seamless Steel Pipe

Speci -cation Grade Chemical Composition [%] Mechanical Properties
C Mn P S Si Cr Mo Cu Ni V Yield STrength Tensile STrength % Elongation (G.L. 50 mm WT 8 mm) e (min.)
Min Max. Min Max. Max. Max. Min. Max Min. Max Min. Max Max Max Max MPa((min.) MPa(min.)
ASTM A - 0.25 - 0.95 0.05 0.045 - - - 0.4 - 0.15 0.40 for S 0.4 0.08 205 330 e=625000 A02/U09
A-53 B - 0.3 - 1.2 0.05 0.045 - - - 0.4 - 0.15 0.40 for S 0.4 0.08 240 415
ASTM
A-106
A - 0.25 0.27 0.93 0.035 0.035 0.1 - - 0.4 - 0.15 0.4 0.4 0.08 205 330 35L / 25T
B - 0.3 0.29 1.06 0.035 0.035 0.1 - - 0.4 - 0.15 0.4 - 0.08 240 415 30L / 16.5T
c - 0.35 0.29 1.06 0.035 0.035 0.1 - - 0.4 - 0.15 0.4 0.08 275 485 30L / 16.5T
API 5L A - 0.22 - 0.9 0.03 0.03 - - - - - - - - - 207 331 -
B - 0.28 - 1.2 0.03 0.03 - - - - - - - - - 241 414 -
X42 - 0.28 - 1.3 0.03 0.03 - - - - - - - - - 290 414 -
X46 - 0.28 - 1.4 0.03 0.03 - - - - - - - - - 317 434 -
X52 - 0.28 - 1.4 0.03 0.03 - - - - - - - - - 359 455 -
X56 - 0.28 - 1.4 0.03 0.03 - - - - - - - - - 386 490 -
X60 - 0.28 - 1.4 0.03 0.03 - - - - - - - - - 448 517 -
X65 - 0.28 - 1.4 0.03 0.03 - - - - - - - - - 448 531 -
X70 - 0.28 - 1.4 0.03 0.03 - - - - - - - - - 483 565 -
API 5L PSL2 BR - 0.24 - 1.2 0.025 0.015 - 0.4 - - - - - - - 241 414 -
X42R - 0.24 - 1.2 0.025 0.015 - 0.4 - - - - - - - 290 414 -
BN - 0.24 - 1.2 0.025 0.015 - - - - - - - - - 317 434 -
X42N - 0.24 - 1.4 0.025 0.015 - 0.4 - - - - - - - 359 455 -
X46N - 0.24 - 1.4 0.025 0.015 - 0.4 - - - - - - - 386 490 -
X52N - 0.24 - 1.4 0.025 0.015 - 0.45 - - - - - - - 448 517 -
X56N - 0.24 - 1.4 0.025 0.015 - 0.45 - - - - - - - 448 531 -
X60N - 0.24 - 1.4 0.025 0.015 - 0.45 - - - - - - - 483 565 -
BQ - 0.18 - 1.4 0.025 0.015 - 0.45 - - - - - - - 241 414 -
X42Q - 0.18 - 1.4 0.025 0.015 - 0.45 - - - - - - - 290 414 -
X46Q - 0.18 - ` 0.025 0.015 - 0.45 - - - - - - - 317 434 -
X52Q - 0.18 - 1.5 0.025 0.015 - 0.45 - - - - - - - 359 455 -
X56Q - 0.18 - 1.5 0.025 0.015 - 0.45 - - - - - - - 386 490 -
X60Q - 0.18 - 1.7 0.025 0.015 - 0.45 - - - - - - - 414 517 -
X65Q - 0.18 - 1.7 0.025 0.015 - 0.45 - - - - - - - 448 531 -
X70Q - 0.18 - 1.8 0.025 0.015 - 0.45 - - - - - - - 483 565 -
X80Q - 0.18 - 1.9 0.025 0.015 - 0.45 - - - - - - - 552 621 -
ASTM 1 - 0.3 0.4 1.06 0.025 0.025 - - - - - - - - - 205 380 35
A333 & A 334 6 - 0.3 0.29 1.06 0.025 0.025 0.1 - - - - - - - - 240 415 30
EN 10305-1/ E 235 - 0.17 - 1.2 0.025 0.025 - 0.35 - - - - - - 0.02 235 340 25
EN10305-4 E 355 0.22 1.6 0.025 0.025 0.55 0.02 355 490 22
EN 10216-1 P195 TR1 - 0.13 - 0.7 0.025 0.02 - 0.35 - 0.3 - 0.08 0.3 0.3 - 195 320 27
P235 TR1 0.16 1.2 0.025 0.02 0.35 0.3 0.08 0.3 0.3 235 360 25
EN 10216-2 P235 GH - 0.16 - 1.2 0.025 0.02 - 0.35 - 0.3 - 0.08 0.3 0.3 0.02 - - -
DIN 2391 St - 45 - 0.17 0.4 - 0.025 0.025 - 0.35 - - - - - - - NBK : 215 / GBK : - NBK : 340 / GBK : 315 NBK : 470
St - 45 - 0.21 0.4 - 0.025 0.025 - 0.35 - - - - - - - NBK : 255 / GBK : - NBK : 440 / GBK : 390 NBK : 570
St - 52 - 0.22 - 1.6 0.025 0.025 - 0.55 - - - - - - - NBK : 355 / GBK : - NBK : 490 / GBK : 490 NBK : 630
ASTM SAE 1010 0.08 0.13 0.20 0.3 0.6 0.04 0.05 - - - - - - - - - - - -
A-519 SAE 1018 0.15 0.28 0.6 0.9 0.04 0.05 - - - - - - - - - - - -
SAE 1026 0.22 0.38 0.6 0.9 0.04 0.05 - - - - - - - - - - - -
SAE 1035 0.32 0.44 0.6 0.9 0.04 0.05 - - - - - - - - - - - -
SAE 1040 0.37 0.21 0.6 0.9 0.04 0.05 - - - - - - - - - - - -
SAE 1518 0.15 0.44 1.1 1.4 0.04 0.05 - - - - - - - - - - - -
SAE 1541 0.36 0.33 1.35 1.65 0.04 0.05 - - - - - - - - - - - -
SAE 4130 0.28 0.4 0.6 0.04 0.04 0.15 0.35 0.8 1.1 0.15 0.25 - - - - - -
ASTM A179 - 0.06 0.18 0.27 0.63 0.035 0.035 - - - - - - - - - 180 325 35
ASTM A192 - 0.06 0.18 0.27 0.63 0.035 0.035 - 0.25 - - - - - - - 180 325 35
ASTM A-1 - 0.27 - 0.93 0.035 0.035 0.1 - - - - - - - - 255 415 30
A 210 C - 0.35 0.29 1.06 0.035 0.035 0.1 - - - - - - - - 275 485 30
ASTM
A 213
T-11 0.05 0.15 0.3 0.6 0.025 0.025 0.5 1 1 1.5 0.44 0.65 - - - 205 415 30
T-12 0.05 0.15 0.3 0.61 0.025 0.025 - 0.5 0.8 1.25 0.44 0.65 - - - 220 415 30
T-22 0.05 0.15 0.3 0.6 0.025 0.025 - 0.5 1.9 2.6 0.87 1.13 - - - 205 415 30
ASTM
A335
P-11 0.05 0.15 0.3 0.6 0.025 0.025 0.5 1 1 1.5 0.44 0.65 - - - 205 415 30
P-12 0.05 0.15 0.3 0.61 0.025 0.025 - 0.5 0.8 1.25 0.44 0.65 - - - 220 415 30
P-22 0.05 0.15 0.3 0.6 0.025 0.025 - 0.5 1.9 2.6 0.87 1.13 - - - 205 415 30
BS 3059 Pt I 320 - 0.16 0.3 0.7 0.04 0.04 0.1 0.35 - - - - - - - 195 320 69,500
BS 3059 Pt II 622-490 0.08 0.15 0.4 0.7 0.03 0.03 - 0.5 2 2.5 0.9 1.2 - - - 275 490 93,000
DIN 1629 St- 37.0 - 0.17 - - 0.04 0.04 - - - - - - - - - WT 16mm = 235 / WT>16mm = 225 350 -
St - 52 - 0.22 - - 0.04 0.035 - - - - - - - - - WT 16mm = 355 / WT>16mm = 345 Long 21 / Trans 19
DIN 17175 St - 35.8 - 0.17 0.4 0.8 0.04 0.04 0.1 0.35 - - - - - - - WT 16mm = 235 / WT>16mm = 225 360 480
St - 45.8 - 0.21 0.4 1.2 0.04 0.04 0.1 0.35 - - - - - - - WT 16mm = 255 / WT>16mm = 245 410 530
IS:1239 Pt I - - - - - 0.05 0.05 - - - - - - - - - 320 -
IS:1161 YST-210 - 0.12 - 0.6 0.04 0.04 - - - - - - - - - 210 330 -
YST-240 - 0.16 - 1.2 0.04 0.04 - - - - - - - - - 240 410 -
YST-310 - 0.25 - 1.3 0.04 0.04 - - - - - - - - - 310 445
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