What is a steel pipe?

What is a steel pipe?
A steel 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.
Seamless steel 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 supply base is rather narrow and prices are, as a consequence, impacted.

SEAMLESS STEEL 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.

CCARBON 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), ASME B36.10 

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), ASME B36.10

 Use scrollbar at the bottom of table.
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), ASME B36.10

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), ASME B36.10

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

Dimensions according to ASME B36.19

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 pipe manufacturing process - What is a steel pipe?

ERW AND LSAW Pipe

An ERW pipe (“electric resistance welding”) is manufactured by cutting, bending and welding steel coils longitudinally. The most common welding technique used for oil and gas pipes is the so-called “high-frequency induction technology” (ERW-HFI), consisting in the application of an induction current on the outer surface of the pipe able to generate a robust seam weld and join the two sides of the steel coil very tightly. No filler materials is therefore used for ERW pipes (differently from LSAW pipes).

ERW pipes are available in sizes between 1/2 and 20 inches, in carbon steel (ASTM A53 is a common grade) and stainless steel (ASTM A312). The dimensions and sizes of ERW pipes are covered by the ASME B36.10 and ASME B36.19 specifications (respectively, carbon and alloy, and stainless steel ERW pipes).

erw pipe manufacturing process - What is a steel pipe?

WHAT MEANS “LSAW PIPE”?

An LSAW pipe (“submerged arc welding”) is manufactured by cutting, bending and welding steel plates (JCOE process). LSAW pipes compete with seamless and ERW pipes in the size range between 16 and 24 inches but become the only option for pipe sizes above 24 inches. The two main types of LSAW pipes are the longitudinal (with a single or double straight seam weld, DSAW) and the spiral type (called, HSAW or SSAW pipe). 

LSAW pipes 1 - What is a steel pipe?

In the oil and gas industry, API 5L LSAW pipes are used for hydrocarbons transmission and distribution over long distances. HSAW/SSAW spiral weld pipes are used for non-critical application as water transmission and distribution (not for oil & gas).

LSAW PIPE MANUFACTURING PROCESS

LSAW pipes are manufactured with the so-called JCOE process, starting from steel plates as illustrated below.

LSAW pipes manufacturing process - What is a steel pipe?

SEAMLESS VS WELDED PIPE

The question “Shall I use seamless or a 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%.

PIPE VS TUBE

What is the difference between pipe vs tube? A pipe is a round tubular to transport or distribute fluids and gases. Steel pipes are designated by a nominal size value (NPS or DN), which represent a rough indication of their inside diameter and fluid conveyance capacity. A tube is a round, rectangular, squared or oval hollow section measured by outside diameter (“OD”) and wall thickness (“WT”), expressed in inches or millimeters. 

pipe vs tube 4 - What is a steel pipe?

Pipes are used for conveying fluids and gases; tubes are used to manufacturing pressure equipment (tubing) and for mechanical applications.

PIPE INSIDE DIAMETER

The word “steel pipe” refers to round hollow sections used for transmission and distribution pipelines and piping systems that convey fluids and gases – such oil & gas, propane, steam, acids, and water.

pipes - What is a steel pipe?

The most important dimension for a steel pipe is the inside diameter (“pipe ID”), which indicates the rough (not the exact) fluid conveyance capacity of the tubular. The ID is expressed in NPS” or “DN” (nominal pipe size, or bore size).

The pipe outside diameter (OD) does not match the nominal size for pipes below NPS 14 inches (a 2 inches pipe, for instance, has an internal flow capacity of approximately 2 inches, but has an outside diameter of 2.375 inches). For pipes of a given NPS, the pipe outside diameter is fixed, whereas the pipe inside diameter decreases by increasing schedule values (pipe wall thickness).

The most important mechanical parameters for pipes are the pressure rating, the yield strength, and the ductility.

The standard combinations of pipe nominal diameter and wall thickness (schedule) are covered by the ASME B36.10 and ASME B36.19 specifications (respectively, carbon and alloy pipes, and stainless steel pipes).

PIPE INSIDE DIAMETER CALCULATOR

As mentioned, the outside diameter of pipes of a specific NPS is constant but the inside diameter of the pipe (ID) changes depending on the pipe schedule.

The pipe ID can be easily calculated, as long as the pipe NPS and schedule are known.

The pipe ID can be calculated by deducting from the pipe NPS the pipe wall thickness multiplied by 2 (the pipe WT can be taken from the schedule). Example: for a 12 NPS pipe (DN 300 mm), schedule 40, the pipe outside diameter and the wall thickness are 12.75 inches (324 mm) and 0.406 inches (10.4 mm).

Therefore, the pipe ID (internal diameter) is 12.75 inches – 2 x 0.406 inches = 11.94 inches, or Pipe ID = 324 mm – 2 x 10.4 mm = 303.2 mm.

It should be noted that this calculation is just theoretical, as pipes have a wall thickness tolerance which is generally +/-12.5% for ASME pipes. Hence the actual ID of a given pipe may differ by +/- 12,5% from the theoretical value.

The pipe ID calculator is available on this page.

TUBE OUTSIDE DIAMETER AND WALL THICKNESS

The word “tube” refers to round, square, rectangular, and oval hollow sections used for pressure equipment (boilers, heaters, and superheaters), for mechanical applications and for instrumentation systems. For these type of applications, the outside diameter and the wall thickness of the tube are the most important dimensions (contrary to pipes) together with its mechanical properties (yield, tensile strength, and elongation) are key.

tubinga213 - What is a steel pipe?

The outside diameter and the wall thickness of a tube (“tube OD”) are expressed in inches or millimeters; the difference between the outside diameter and the wall thickness, multiplied by two, defines the inside diameter of the tube.

In terms of pipe vs tube pricing, steel tubes are generally more expensive than steel pipe due to their stricter manufacturing tolerances and mills productivity (tons produced by the hour). The most important physical properties of steel tubes are the hardness, the tensile strength, and highly precise dimensions.

TOP 10 DIFFERENCES PIPE VS TUBE

To summarize the difference between pipe and tube and the pipe meaning vs. tube meaning

PIPE VS TUBE: DIFFERENCE AREAS PIPE TUBE
1 Key Dimensions The most important dimension for a pipe is the inside diameter (ID), expressed in NPS (nominal pipe size) or DN (nominal diameter), which defines its fluid conveyance capacity. The NPS does not match the true inside diameter, it is a rough indication The most important dimensions for a steel tube are the outside diameter (OD) and the wall thickness (WT). These parameters are expressed in inches or millimeters and express the true dimensional value of the hollow section.
2 Wall Thickness The thickness of a steel pipe is designated with a “Schedule” value (the most common are Sch. 40, Sch. STD., Sch. XS/XH, Sch. XXS). Two pipes of different NPS and same schedule have different wall thicknesses in inches or millimeters. The wall thickness of a steel tube is expressed in inches or millimeters. For tubing, the wall thickness is measured also with a gage nomenclature (BWG, SWG).
3 Tubular Shape Round only Round, rectangular, square, oval
4 Production range Extensive (up to 80 inches and above) Narrower range for tubing (up to 5 inches), larger for steel tubes for mechanical applications
5 Tolerances (straightness, dimensions, roundness, etc) Tolerances are set, but rather loose Steel tubes are produced to very strict tolerances. Tubulars undergo several dimensional quality checks, such as straightness, roundness, wall thickness, surface, during the manufacturing process.
6 Production Process Pipes are generally made to stock with highly automated and efficient processes, i.e. pipe mills produce on a continuous basis and feed distributors stock around the world. Tubes manufacturing is more lengthy and laborious
7 Delivery time Can be short Generally longer
8 Market price Relatively lower price per ton than steel tubes Higher due to lower mills productivity per hour, and due to the stricter requirements in terms of tolerances and inspections
9 Materials Wide range of materials Tubing is available in carbon steel, low alloy, stainless steel and nickel-alloys; steel tubes for mechanical applications are mostly of carbon steel
10 End Connections The most common are beveled and plain ends Threaded and grooved ends are available for quicker connections on site

WHAT ARE OCTG PIPES

OCTG pipes are tubular products used for onshore and offshore oil & gas upstream operations. The OCTG pipe family includes casing pipes (to stabilize the wellbore), tubing pipes (to transport hydrocarbons from the reserve to the surface) and drill pipes to perforate the soil. The dimensions, tolerances, and materials for “Oil Country Tubular Goods” are covered by the API 5CT specification.

octg pipes 1 - What is a steel pipe?

Three types of pipes belong to the OCTG family:

Casing pipes are used to stabilize the wellbore. A casing pipe is subject to axial tensions and to internal pressures generated by the pumped oil or gas, by their heavyweight and the external pressures coming from the surrounding rocks

Tubing pipes are tubular goods through which the oil or gas is transported from the wellbore to the surface. Tubing segments are generally around 30′ long with a threaded connection on each end (standard or premium connections are available)

Drill pipes are heavyweight seamless tubular that rotates the drill bit and circulates the drilling fluid. Pipe segments of 30′ are coupled with tool joints. Drill pipe is subject to high torque by drilling, axial tension by their weight, and internal pressure due to the purging of the drilling fluid. Additionally, alternating bending loads due to non-vertical or deflected drilling may be superimposed on these basic loading patterns

OCTG Tubular

octg tubulars - What is a steel pipe?

API5CT CASING AND TUBING PIPES

The API 5CT specification covers seamless and welded casing and tubing pipes for upstream operations (pipes that belong to the OCTG family, as illustrated above). The application of casing and tubing pipes is shown in the picture:octg pipes 1 - What is a steel pipe?

API 5CT CASING PIPES

Casing pipes - What is a steel pipe?

Casing pipes scope

Casing pipes are a key structural component for an oil & gas well and have the following scope:

  • Keep the borehole stability in the well
  • Prevent the bore contamination from water sands
  • Prevent water from producing formations
  • Exercise a tight control of the wellbore pressures during the drilling, production, and repair operations

Casing pipes are used to install:

  • Blowout Preventers (BOP)
  • Other wellhead equipment necessary to extract hydrocarbons
  • Production tubing and packers

Casing pipes are also one major individual component of the overall cost of the well,  therefore the correct selection of the casing size, materials, connectors, and depth shall be at the top of design engineers (for cost and efficiency reasons).

The six basic types of casing strings are:

  • Conductor Casing
  • Surface Casing
  • Intermediate Casing
  • Production Casing
  • Liner
  • Liner tieback casing

Oilfield casing pipes are positioned into the wellbore and cemented in place to secure both subsurface formations and the wellbore from collapsing, also to enable drilling mud to circulate and extraction to take place. The strict quality requirement for steel is due to the harsh working conditions of the casing. The steel product should be produced and checked in accordance with special standards or specifications. ISO 11960 and API Spec 5CT have specified the steel product standards of the casing.

Casing pipes sizes and materials

Casing pipes are available in a diameter range 4 1/2  to 20 inches (the dimensions of API5CT casing pipes are shown in this article), and in the following materials: H-40, J-55, K-55, N-80, L-80/C, 90/T, 95, P110, Q-125. Consult this article to learn more about the materials for API5CT pipes.

Casing pipes connections

The main types of connections for casing pipes are STC (short threads), LTC (long threads), BTC (buttress threads) and premium gas-tight connections.

API 5CT TUBING PIPES

tubing pipes api 5ct - What is a steel pipe?

Tubing pipes scope

Tubing pipes are used to bring oil and gas from the underground reserves up to the field for further processing. Tubing pipes need resistance to mechanical stress as they are subject to very high loads and deformations during the production operations. In addition, tubing pipes sizes should be properly calculated to support the expected oil and gas flow from the ground to the surface (a too small diameter would decrease the production rate and the return on investment on the wellbore licenses, whereas too large tubing would generate non-recoverable costs due to the greater amount of steel used for the bore construction vs. the actual requirement (steel for the casing and tubing pipes).

Tubing pipes sizes and materials

Tubing pipes are manufactured in seamless and welded execution, in the size range 1.050 to 5 1/2 inches (consult this article to see the AP5CT tubing pipes sizes) and in the following material grades: H-40, J-55, K-55, N-80, L-80, C-90, T-95, P-110, Q-125 (more details about API 5CT tubing materials are in this article).

Tubing pipes connections

The main types of connections for tubing pipes are NUE (non-upset), EUE (external upset) and premium. Corrosion resistance under sour service conditions is a very important OCTG characteristic, especially for casing and tubing.

API5CT PIPE MANUFACTURING PROCESS

The manufacturing processes of casing and tubing pipes include:

  • Continuous mandrel-rolling process and the push bench process for sizes between 21 and 178 mm OD.
  • Plug mill rolling for sizes between 140 and 406 mm OD.
  • Cross-roll piercing and Pilger rolling for sizes between 250 and 660 mm OD.

These processes typically do not allow the thermomechanical processing customary for the strip and plate products used for welded pipes. Therefore, the high-strength seamless pipe must be produced by increasing the alloying content in combination with a suitable heat treatment such as quench & tempering.

Meeting the fundamental requirement of a fully martensitic microstructure even at large pipe wall thickness requires good hardenability. Chrome (Cr) and Manganese (Mn) are the main alloying elements used to produce good hardenability in conventional heat-treatable steel. However, the requirement for good sulfide stress cracking (SSC) resistance limits their use. Mn tends to segregate during continuous casting and can form large MnS inclusions that reduce hydrogen induced cracking (HIC) resistance. Higher levels of Cr can lead to the formation of Cr7C3 precipitates with coarse plate-shaped morphology, which acts as hydrogen collectors and cracks initiators. Alloying with Molybdenum can overcome the limitations of Mn and Cr alloying. Mo is a much stronger hardener than Mn and Cr, so it can easily recover the effect of a reduced amount of these elements.

Traditionally, OCTG grades were carbon-manganese steels (up to the 55-KSI strength level) or Mo-containing grades up to 0.4% Mo. In recent years, deep well-drilling and reservoirs containing contaminants that cause corrosive attack have created a strong demand for higher strength materials resistant to hydrogen embrittlement and SCC. Highly tempered martensite is the structure most resistant to SSC at higher strength levels, and 0.75% is the Mo concentration that produces the optimum combination of yield strength and to SSC resistance

API5CT COUPLINGS

API5CT TUBING COUPLINGS

API 5CT Tubing OD Coupling OD Length Unit Weight
Inches Inches Inches lbs
API EUE Tubing Couplings 1.315 1.66 3.25
1.66 2.054 3.5
1.9 2.2 3.75
API NUE Tubing Couplings 2 3/8 3.063 4.875
2 7/8 3.668 5.25
3 1/2 4.5 5.75

API 5CT CASING COUPLINGS SHORT-THREAD

API 5CT Casing OD Short Thread
Coupling OD
Coupling Length Unit Weight
lbs
Inches Inches Inches
API Casing Couplings Short Thread 41/2 5.000 6.250
51/2 6.050 6.750

API 5CT CASING COUPLINGS LONG-THREAD

API 5CT Casing OD Long Thread
Coupling OD
Length Weight per Coupling
Inches Inches Inches
API Casing Couplings Long Thread 41/2 5.000 6.250
51/2 6.050 6.750

PIPING MATERIALS

which flange or valve material matches a given pipe material?

The piping materials matching chart maps how to mate the materials of different piping products, such as pipes, valves, fittings, flanges, and stud bolts.

The table shows, for example, that an A106 Gr. A pipe matches with ASTM A234 butt weld fitting, with an ASTM A105 forged fitting (or valve), with a A216 WCB cast valve and with ASTM A193 B7 stud bolts. The same logic applies to any other ASTM material grades.

Of course, the final decision about piping materials has to be taken by the design engineer and the given indications shall be taken with due care.

PIPING MATERIALS PIPES BW FITTINGS FORGINGS* CAST VALVES BOLT SETS
Carbon Steel A106 Gr A A234 Gr WPA A105 A216 Gr WCB A193 Gr B7
A194 Gr 2H
A106 Gr B A234 Gr WPB A105 A216 Gr WCB
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
A194 Gr 2H
A335 Gr P11 A234 Gr WP11 A182 Gr F11 A217 Gr WC6
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
A 335 Gr P91 A234 Gr WP91 A182 Fr F91
Carbon Steel
Alloy Low-Temp
A333 Gr 6 A420 Gr WPL6 A350 Gr LF2 A352 Gr LCB A320 Gr L7
A194 Gr 7
A333 Gr 3 A420 Gr WPL3 A350 Gr LF3 A352 Gr LC3
Austenitic
Stainless Steel
A312 Gr TP304 A403 Gr WP304 A182 Gr F304 A182 Gr F304 A193 Gr B8
A194 Gr 8
A312 Gr TP316 A403 Gr WP316 A182 Gr F316 A182 Gr F316
A312 Gr TP321 A403 Gr WP321 A182 Gr F321 A182 Gr F321
A312 Gr TP347 A403 Gr WP347 A182 Gr F347 A182 Gr F347
* Forgings include: forged fittings, flanges, forged valves, some gaskets

MOST COMMON PIPING MATERIALS

PIPE MATERIALS

  • A106: Specification for carbon steel pipe for high-temperature service. For more info about A106 pipes, read here
  • A335: Specification for seamless ferritic alloy-steel pipe for high-temperature service. For more info about chrome-alloy pipes, read here
  • A333: Specification for wall seamless and welded carbon and alloy steel pipe intended for use at low temperatures. For more info about LTCS pipes, read here
  • A312: Standard specification for seamless, straight-seam welded, and cold worked welded austenitic stainless steel pipe intended for high-temperature and general corrosive service. For more information about stainless steel pipes, read here.

VALVE MATERIALS

  • A216: Specification for carbon steel castings for Valves, flanges, fittings, or other pressure-containing parts for high-temperature service and of the quality suitable for assembly with other castings or wrought steel parts by fusion welding. For more information about carbon steel valves, read here
  • A217: Specification for steel castings, martensitic stainless steel and alloys steel castings for Valves, flanges, fittings, and other pressure-containing parts intended primarily for high-temperature and corrosive service.
  • A352: Specification for steel castings for Valves, flanges, fittings, and other pressure-containing parts intended primarily for low-temperature service.
  • A182: This specification covers forged or rolled alloy and stainless steel pipe flanges, forged fittings, and Valves and parts for high-temperature service. Find more information about forged body valves here.

FLANGE MATERIALS

  • A105: Specification for standards for forged carbon steel piping components, that is, flanges, fittings, Valves, and similar parts, for use in pressure systems at ambient and higher-temperature service conditions. To learn more about forged flanges materials, read this article
  • A182: This specification covers forged or rolled alloy and stainless steel pipe flanges, forged fittings, and Valves and parts for high-temperature service.
  • A350: Specification for several grades of carbon and low alloy steel forged or ring-rolled flanges, forged fittings and Valves for low-temperature service.

PIPE FITTINGS MATERIALS

  • A234: Specification for wrought carbon steel and alloy steel fittings of seamless and welded construction.
  • A420: Standard specification for piping fittings of wrought carbon steel and alloy steel for low-temperature service.
  • A403: Standard specification for wrought austenitic stainless steel piping fittings.

STUD BOLT MATERIALS

  • A193: Standard specification for alloy and stainless steel bolting material for pressure vessels, Valves, flanges, and fittings for high temperature or high-pressure service, or other special purpose applications.
  • A320: Standard Specification for Alloy-Steel and Stainless Steel Bolting Materials for Low-Temperature Service.
  • A194: Standard specification for nuts in different materials

PIPE LENGTH AND PIPE ENDS

PIPE LENGTH (SRL, DRL)

The length of a pipe measures the distance in meters, or feet, between the two ends of a tubular section. Generally, pipes below 2 inches in diameter are manufactured in single random lengths (“SRL”, 5 to 7 meters), larger pipes in double random lengths (“DRL”, 11 to 13 meters).

The most common terms used to designate the length of steel pipes are:

  • SRL (single random pipe length): 5-7 meters in length – generally used for pipes below 2 inches
  • DRL (double random pipe length): 11-13 meters per pipe, for pipes above 2 inches
  • Cut Lengths: pipes are cut at specific lengths according to project specification. Cut lengths pipes are generally more expensive than standard but may save EPC and End-Users the costs related to welding activities.

PIPE LENGTH TOLERANCE

In case of “cut lengths” pipes, the allowed tolerance is between within -0mm / +6mm.

PIPE END TYPES

The pipe end concept refers to the type of finish applied to the extremities of the tubular, and the consequent type of pipe to pipe connection that will be necessary to deploy a pipeline or a piping system.

Beveled ends 1 - What is a steel pipe?

The most common types of pipe end connections are:

  • Plain ends (PE): ASME ANSI B16.5. PE ends are generally used for smaller diameters and imply the usage of slip-on flanges, and socket weld fittings.
  • Beveled ends (BE): ASME ANSI B16.5. BE ends are the most common type of finish (joints are realized by welding pipes with butt weld fittings and flanges).
  • Threaded ends (TE): ASME B1.20.1 NPT. TE ends require threaded fittings and flanges and are typical for small size pipelines.
  • Threaded and coupled ends (T&C), generally used for gas distribution
  • Grooved ends (example Victaulic pipes)
1505904655 2602 Plainendpipe 300x231 - What is a steel pipe? 1505904655 8969 BeveledEndPipe 300x231 - What is a steel pipe?1505904655 7987 Threadedendpipe 300x231 - What is a steel pipe?1505904656 4848 Groovedendpipe 300x232 - What is a steel pipe?
The image shows (left to right) plain, beveled, threaded and grooved pipe ends.

Source: China Steel Pipes Manufacturer – Yaang Pipe Industry Co., Limited (www.pipelinedubai.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 sales@pipelinedubai.com

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

References:

  • https://www.yaang.com

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