A seamless pipe is a round hollow section manufactured by drawing a solid billet (in carbon, alloy, stainless or nickel alloy steel) through a piercing rod. Seamless pipes are considered superior to welded pipes as they are built using monolithic steel billets, with intrinsic mechanical strength, without seam welds.

 

Carbon steel seamless pipes are used for the transmission and distribution of oil, gas, steam, and chemicals. Stainless steel seamless pipes offer enhanced resistance to corrosion at high temperature and pressure.

Seamless steel pipes have a higher price per ton than welded pipes, due to their fairly complex production process and due to the oligopolistic nature of the market. For specific sizes and specifications (example 20 inch pipes or seamless high wall thickness ASTM A335 P91 pipes), the number of pipe suppliers is rather narrow and prices are, as a consequence, impacted.

Pipes may have different color codes, based on the type of conveyed fluid. To note, also, that the term “pipe” differs from the word “pipe” (click on this link to learn about the differences between pipe and tube).

 

SEAMLESS PIPE DIMENSIONS

  • Carbon and low-alloy seamless pipes are manufactured according to the ASME B36.10 specification, in sizes between 1/8 and 24 inches and with multiple schedule designations, representing the wall thickness of the pipe (pipe expanders are used to reach higher nominal sizes);
  • Stainless steel seamless pipes (and higher grades, as nickel-alloy) are manufactured according to the ASME B36.19 specification, generally in sizes between 1/8 and 12 inches;
  • Carbon, alloy and stainless seamless pipes for upstream oil operations (OCTG pipes) are covered by the API 5CT specification.

The ASME pipe size specifications can be purchased online from the ASME website or from the IHS online store.

The API5CT specification can be downloaded from the official API website following this link.

 

CARBON SEAMLESS PIPE DIMENSIONS NPS 1-8″ TO 3 1-2″

First line: pipe wall thickness in inches; second line: pipe WT in mm (by nominal pipe size and pipe schedule), Source: Wikipedia

SEAMLESS
PIPE SIZE
DN OD INCH (mm) SEAMLESS PIPE WALL THICKNESS (WT, in mm)
SCH 5s SCH 10s/ 20 SCH 30 SCH 40(s) / STD SCH 80(s) /XS SCH 120 SCH 160 XXS
1/8 6 0.404 (10.26) 0.035 (0.889) 0.049 (1.245) 0.057 (1.448) 0.068 (1.727) 0.095 (2.413)
1/4 8 0.540 (13.72) 0.049 (1.245) 0.065 (1.651) 0.073 (1.854) 0.088 (2.235) 0.119 (3.023)
3/8 10 0.675 (17.15) 0.049 (1.245) 0.065 (1.651) 0.073 (1.854) 0.091 (2.311) 0.126 (3.200)
1/2 15 0.840 (21.34) 0.065 (1.651) 0.083 (2.108) 0.095 (2.413) 0.109 (2.769) 0.147 (3.734) 0.188 (4.775) 0.294 (7.468)
3/4 20 1.050 (26.67) 0.065 (1.651) 0.083 (2.108) 0.095 (2.413) 0.113 (2.870) 0.154 (3.912) 0.219 (5.563) 0.308 (7.823)
1 25 1.315 (33.40) 0.065 (1.651) 0.109 (2.769) 0.114 (2.896) 0.133 (3.378) 0.179 (4.547) 0.250 (6.350) 0.358 (9.093)
1 1/4 32 1.660 (42.16) 0.065 (1.651) 0.109 (2.769) 0.117 (2.972) 0.140 (3.556) 0.191 (4.851) 0.250 (6.350) 0.382 (9.703)
1 1/2 40 1.900 (48.26) 0.065 (1.651) 0.109 (2.769) 0.125 (3.175) 0.145 (3.683) 0.200 (5.080) 0.281 (7.137) 0.400 (10.160)
2 50 2.375 (60.33) 0.065 (1.651) 0.109 (2.769) 0.125 (3.175) 0.154 (3.912) 0.218 (5.537) 0.250 (6.350) 0.344 (8.738) 0.436 (11.074)
2 1/2 65 2.875 (73.03) 0.083 (2.108) 0.120 (3.048) 0.188 (4.775) 0.203 (5.156) 0.276 (7.010) 0.300 (7.620) 0.375 (9.525) 0.552 (14.021)
3 80 3.500 (88.90) 0.083 (2.108) 0.120 (3.048) 0.188 (4.775) 0.216 (5.486) 0.300 (7.620) 0.350 (8.890) 0.438 (11.125) 0.600 (15.240)
3 1/2 90 4.000 (101.60) 0.083 (2.108) 0.120 (3.048) 0.188 (4.775) 0.226 (5.740) 0.318 (8.077) 0.636 (16.154)

 

 

CARBON SEAMLESS PIPE DIMENSIONS PIPES NPS 4″ – 9″

First line: pipe wall thickness in inches; second line: pipe WT in mm (by nominal pipe size and pipe schedule),Source: Wikipedia

SEAMLESS
PIPE SIZE
DN OD INCH (mm) SEAMLESS PIPE WALL THICKNESS (WT, in mm)
SCH 5 SCH 10(S) SCH 20 SCH 30 SCH 40(s) /STD SCH 60 SCH 80(S)
/XS
SCH 100 SCH 120 SCH 140 SCH 160 XXS
4 100 4.500 (114.30) 0.083 (2.108) 0.120 (3.048) 0.188 (4.775) 0.237 (6.020) 0.337 (8.560) 0.437 (11.100) 0.531 (13.487) 0.674 (17.120)
4 1/2 115 5.000 (127.00) 0.247 (6.274) 0.355 (9.017) 0.710 (18.034)
5 125 5.563 (141.30) 0.109 (2.769) 0.134 (3.404) 0.258 (6.553) 0.375 (9.525) 0.500 (12.700) 0.625 (15.875) 0.750 (19.050)
6 150 6.625 (168.28) 0.109 (2.769) 0.134 (3.404) 0.280 (7.112) 0.432 (10.973) 0.562 (14.275) 0.719 (18.263) 0.864 (21.946)
7 7.625 (193.68) 0.301 (7.645) 0.500 (12.700) 0.875 (22.225)
8 200 8.625 (219.08) 0.109 (2.769) 0.148 (3.759) 0.250 (6.350) 0.277 (7.036) 0.322 (8.179) 0.406 (10.312) 0.500 (12.700) 0.593 (15.062) 0.719 (18.263) 0.812 (20.625) 0.875 (22.225)
9 9.625 (244.48) 0.342 (8.687) 0.500 (12.700)

 

 

CARBON SEAMLESS PIPE DIMENSIONS NPS 10″ – 24″ ( BELOW SCH. 40)

First line: pipe wall thickness in inches; second line: pipe WT in mm (by nominal pipe size and pipe schedule), Source: Wikipedia

SEAMLESS
PIPE SIZE
DN OD
INCH (mm)
SEAMLESS PIPE WALL THICKNESS (WT, in mm)
SCH 5S SCH 5 SCH 10S SCH 10 SCH 20 SCH 30 SCH STD/40S
10 250 10.75 (273.05) 0.134 (3.404) 0.134 (3.404) 0.165 (4.191) 0.165 (4.191) 0.250 (6.350) 0.307 (7.798) 0.365 (9.271)
12 300 12.75 (323.85) 0.156 (3.962) 0.156 (3.962) 0.180 (4.572) 0.180 (4.572) 0.250 (6.350) 0.330 (8.382) 0.375 (9.525)
14 350 14.00 (355.60) 0.156 (3.962) 0.156 (3.962) 0.188 (4.775) 0.250 (6.350) 0.312 (7.925) 0.375 (9.525) 0.375 (9.525)
16 400 16.00 (406.40) 0.165 (4.191) 0.165 (4.191) 0.188 (4.775) 0.250 (6.350) 0.312 (7.925) 0.375 (9.525) 0.375 (9.525)
18 450 18.00 (457.20) 0.165 (4.191) 0.165 (4.191) 0.188 (4.775) 0.250 (6.350) 0.312 (7.925) 0.437 (11.100) 0.375 (9.525)
20 500 20.00 (508.00) 0.188 (4.775) 0.188 (4.775) 0.218 (5.537) 0.250 (6.350) 0.375 (9.525) 0.500 (12.700) 0.375 (9.525)
22 550 22.00 (558.80) 0.188 (4.775) 0.188 (4.775) 0.218 (5.537) 0.250 (6.350) 0.375 (9.525) 0.500 (12.700) 0.375 (9.525)
24 600 24.00 (609.60) 0.218 (5.537) 0.218 (5.537) 0.250 (6.350) 0.250 (6.350) 0.375 (9.525) 0.562 (14.275) 0.375 (9.525)

 

 

CARBON SEAMLESS PIPE DIMENSIONS NPS 14″- 24″ (ABOVE SCH. 40)

First line: pipe wall thickness in inches; second line: pipe WT in mm (by nominal pipe size and pipe schedule), Source: Wikipedia

SEAMLESS
PIPE SIZE
DN SEAMLESS PIPE WALL THICKNESS (WT, in mm)
SCH 40 SCH 60 SCH 80S/XS SCH 80 SCH 100 SCH 120 SCH 140 SCH 160
14 350 0.437 (11.100) 0.593 (15.062) 0.500 (12.700) 0.750 (19.050) 0.937 (23.800) 1.093 (27.762) 1.250 (31.750) 1.406 (35.712)
16 400 0.500 (12.700) 0.656 (16.662) 0.500 (12.700) 0.843 (21.412) 1.031 (26.187) 1.218 (30.937) 1.437 (36.500) 1.593 (40.462)
18 450 0.562 (14.275) 0.750 (19.050) 0.500 (12.700) 0.937 (23.800) 1.156 (29.362) 1.375 (34.925) 1.562 (39.675) 1.781 (45.237)
20 500 0.593 (15.062) 0.812 (20.625) 0.500 (12.700) 1.031 (26.187) 1.280 (32.512) 1.500 (38.100) 1.750 (44.450) 1.968 (49.987)
22 550 0.875 (22.225) 0.500 (12.700) 1.125 (28.575) 1.375 (34.925) 1.625 (41.275) 1.875 (47.625) 2.125 (53.975)
24 600 0.687 (17.450) 0.968 (24.587) 0.500 (12.700) 1.218 (30.937) 1.531 (38.887) 1.812 (46.025) 2.062 (52.375) 2.343 (59.512)

 

 

STAINLESS STEEL SEAMLESS PIPE DIMENSION

Source: Wikipedia

Stainless Steel Seamless Pipe Size
(inches)
Outside
Diameter
Seamless Pipe Schedule
Sch. 5S Sch. 10S Sch. 40S Sch. 80S
(mm) (inches) Pipe Wall Thickness and Weight
mm
(in)
kg/m mm
(in)
kg/m mm
(in)
kg/m mm
(in)
kg/m
1/8 10.3 0.405 1.25
(0.049)
0.28 1.73
(0.068)
0.37 2.42
(0.095)
0.47
1/4 13.7 0.540 1.66
(0.065)
0.49 2.24
(0.088)
0.63 3.03
(0.119)
0.80
3/8 17.2 0.675 1.66
(0.065)
0.63 2.32
(0.091)
0.85 3.20
(0.126)
1.10
1/2 21.3 0.840 1.65
(0.065)
0.81 2.11
(0.083)
1.00 2.77
(0.109)
1.27 3.74
(0.147)
1.62
3/4 26.7 1.050 1.65
(0.065)
1.02 2.11
(0.083)
1.28 2.87
(0.113)
1.68 3.92
(0.154)
2.20
1 33.4 1.315 1.65
(0.065)
1.30 2.77
(0.109)
2.09 3.38
(0.133)
2.50 4.55
(0.179)
3.24
1 1/4 42.2 1.660 1.65
(0.065)
1.66 2.77
(0.109)
2.69 3.56
(0.140)
3.39 4.86
(0.191)
4.47
1 1/2 48.3 1.900 1.65
(0.065)
1.91 2.77
(0.109)
3.11 3.69
(0.145)
4.06 5.08
(0.200)
5.41
2 60.3 2.375 1.65
(0.065)
2.40 2.77
(0.109)
3.93 3.92
(0.154)
5.45 5.54
(0.218)
7.49
2 1/2 73.0 2.875 2.11
(0.083)
3.69 3.05
(0.120)
5.26 5.16
(0.203)
8.64 7.01
(0.276)
11.4
3 88.9 3.500 2.11
(0.083)
4.52 3.05
(0.120)
6.46 5.49
(0.216)
11.3 7.62
(0.300)
15.3
3 1/2 101.6 4.000 2.11
(0.083)
5.18 3.05
(0.120)
7.41 5.74
(0.226)
13.6 8.08
(0.318)
18.6
4 114.3 4.500 2.11
(0.083)
5.84 3.05
(0.120)
8.37 6.02
(0.237)
16.1 8.56
(0.337)
22.3
5 141.3 5.563 2.77
(0.109)
9.46 3.41
(0.134)
11.6 6.56
(0.258)
21.8 9.53
(0.375)
31.0
6 168.3 6.625 2.77
(0.109)
11.3 3.41
(0.134)
13.9 7.12
(0.280)
28.3 10.98
(0.432)
42.6
8 219.1 8.625 2.77
(0.109)
14.8 3.76
(0.148)
20.0 8.18
(0.322)
42.5 12.70
(0.500)
64.6
10 273.1 10.750 3.41
(0.134)
22.7 4.20
(0.165)
27.8 9.28
(0.365)
60.4 12.70
(0.500)
81.5
12 323.9 12.750 3.97
(0.156)
31.3 4.58
(0.180)
36.1 9.53
(0.375)
73.9 12.70
(0.500)
97.4

 

SEAMLESS PIPE MATERIALS

The most common material specifications for seamless pipe are:

  • ASTM A53 (black and galvanized pipes, seamless and welded)
  • ASTM A106 (carbon seamless pipe for high-temperature service)
  • ASTM A333 (carbon seamless pipe low-temperature service)
  • ASTM A335 (Chrome Moly pipe, or low alloy seamless pipe)
  • API 5L (carbon steel line pipes)

 

SEAMLESS PIPE MANUFACTURING PROCESS

Seamless pipes from 1/8 to 6 inch. are manufactured with the so-called “plug mill process” or the “extrusion process” (used for smaller diameters), whereas the “mandrel mill process” is used for larger diameters.

Seamless pipes manufacturing process

 

Seamless Steel Pipe Manufacturing Process (source: Tenaris Youtube Channel)

 

SEAMLESS VS WELDED PIPE

The question “Shall I use seamless or welded pipes for my project?” is coming up over and over. Each of the two has different advantages and disadvantages, which should be pondered to take a proper decision:

 

SEAMLESS PIPE PROS AND CONS

  • Seamless pipes are manufactured out of a solid block of steel and do not have any weld seam, which may represent a weak area (subject to corrosion, erosion and, general failure)
  • Seamless pipes have more predictable and precise shapes, in terms of roundness and ovality, compared to welded pipes.
  • The main disadvantage of seamless pipes is that their cost per ton is higher than the cost of equivalent ERW or LSAW pipes (Seamless vs ERW pipes compete in the range 2 to 20 inches, Seamless vs LSAW in the dimensional range 16 to 24 inches)
  • Delivery times may be longer, as there are fewer manufacturers of seamless pipes in the world compared to the number of welded pipe companies
  • Seamless pipes may have an inconsistent wall thickness across their length, indeed the general tolerance is +/- 12.5%

 

WELDED PIPE PROS AND CONS

  • Welded pipes are cheaper than seamless (ERW HFI type), as they are manufactured using steel coils as feedstock in simpler plants
  • Welded pipes have shorter lead times than seamless pipes, as the manufacturing base is way larger
  • Welded pipes have a consistent wall thickness, as they are manufactured using coils (ERW) or plates (LSAW) that have a strictly controlled thickness
  • The major “defect” attributed to welded pipes is that the presence of a weld seam constitutes a weakness factor. Whereas this may have been true in the past, this is becoming less and less true with the advances of the welding technologies in the last ten years.

Conclusion: modern ERW-HFI welded pipes are absolutely a valid alternative to seamless pipes and help end users reduce prices and lead times between 20 and 25%.

 

SEAMLESS PIPE PRICES

Looking for the price of seamless pipes? Click on the image and check our online tool to estimate steel pipe prices.

Seamless pipes price

The tool estimates the price for seamless pipes manufactured in Europe and Asia, for example:

What is a schedule 40 steel pipe price (6 inches, API 5L Gr X52)?

Even if our price estimates are reliable, prices shall always be double checked with seamless pipe manufacturers, suppliers and distributors.

 

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