Casing and Tubing

Casing and Tubing

The American Petroleum Institute (API) and the International Organization for Standardization (ISO) have established two basic types of pipes used for exploration and production in the oil and gas industry: casing and tubing. Casing and Tubing also known as OCTG. Casing and tubing strings are the main parts of the well construction. All wells drilled for the purpose of oil or gas production (or injecting materials into underground formations) must be cased with material with sufficient strength and functionality. Well casing  pipe is a pipe used in oil, gas, or water wells to protect the well walls and stabilize the wellbore.Casing pipe is used to line the drilled borehole that is being utilized for oil extraction. Similar to drill pipes, oil well casing pipe  is also subjected to axial tension and therefore needs to be made from high-quality, strong steel. Casing (well  pipe casing) is a large-diameter pipe fixed in the borehole using cement.Tubing is the pipe used after drilling is completed to transport crude oil and natural gas from the oil or gas reservoir to the surface.

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Sizes of Casing and Tubing

Casing Pipe Sizes
Outside Diameter: 4 1/2–20 inches (114.3–508 mm)
Nominal Weight: 9.5–169 lb/ft (ppf), depending on pipe size and wall thickness
Length Range: R1, R2, and R3, subject to availability and order requirements

Tubing Pipe Sizes
Tubing pipes are selected according to well production requirements and the specified completion design.
Outside Diameter: 48.26–114.3 mm (1.9–4 1/2 inches)
Nominal Weight: Depends on the specified outside diameter, wall thickness, and tubing specification
Length Range: R1, R2, and R3, subject to availability and order requirements
Note: Confirm the required dimensions, nominal weight, steel grade, connection type, and length range against the applicable product specification before placing an order.

Types of Casing and Tubing

Casing Types

Casing pipes stabilize the wellbore, isolate underground formations, and protect freshwater zones during oil and gas drilling. Common types include:
Conductor Casing: Provides initial wellbore stability and supports drilling operations.
Surface Casing: Protects freshwater zones and supports wellhead and BOP equipment.
Intermediate Casing: Isolates unstable formations and abnormal-pressure zones.
Production Casing: Supports the production interval and isolates the producing formation.
Production Liner: Extends from a previously installed casing string, potentially reducing material and installation costs.

Tubing Types
Tubing carries oil, gas, and other well fluids to the surface through the production casing. Common tubing connection types include:
Non-Upset Tubing (NU): Has ends without an external upset.
External-Upset Tubing (EU): Has enlarged ends to accommodate the specified threaded connection.
Integral-Joint Tubing (IJ): Uses an int

Grades of Casing and Tubing

API 5CT H40
API 5CT J55
API 5CT K55
API 5CT M65
API 5CT N80 (1,Q)
API 5CT L80 (9Cr,13Cr)
API 5CT C90
API 5CT T95
API 5CT P110

API 5CT Q125

Casing and tubing share many of the same API 5CT steel grades, including J55, K55, N80, L80, and P110, although the available grades depend on product specifications and application requirements.

Application of Casing and Tubing

Applications of Casing Pipe
Casing pipes provide structural support and isolate underground formations during oil and gas drilling and production. Their main applications include:
Stabilizing the wellbore and helping prevent formation collapse.
Isolating freshwater zones and high-pressure formations.
Providing support for the wellhead and production equipment.
Helping prevent fluid migration between underground formations.
Providing a secure wellbore structure for subsequent drilling and completion operations.

Applications of Tubing Pipe
Tubing pipes provide a flow path for oil, natural gas, and other well fluids from the producing formation to the surface. Their main applications include:
Transporting oil and natural gas during production.
Supporting controlled fluid flow from the well.
Working as part of the well completion system.
Allowing retrieval or replacement during well servicing, depending on the completion design.
Casing and tubing work together in oil and gas wells, but they serve different purposes: casing supports and isolates the wellbore, while tubing carries production fluids to the surface.

Casing and Tubing Casing and Tubing

Connections of Casing and Tubing

SC: Short round thread casing
LC: Long round thread casing
BC: Buttress thread casing
NU: Non-upset tubing
EU: External upset tubing
IJ: Integral tubing connections

Colour Code of Casing and Tubing

Grade Colour Code Pipe
 Heat Treatment

Characteristics and
Recommendation

J55


Normalized, Normalized and Tempered or quenched and Tempered
 Tubing & Casing for general service

K55


Normalized, Normalized and Tempered or quenched and Tempered
 Casing for general service

N80 Type 1


Normalized or Normalized and Tempered
 Tubing & Casing for general service

N80 Type Q


Quenched and Tempered
 Tubing & Casing for general service

L80 Type 1


Quenched and Tempered
 Tubing & Casing with controlled yield range for sour well service

L80 9 Cr


Quenched and Tempered
 Tubing & Casing for oil & gas wells affected by CO2 corrosion

L80 13 Cr


Quenched and Tempered
 Tubing & Casing for oil & gas wells affected by CO2 corrosion

C90 Type 1


Quenched and Tempered
 Hight strength Tubing & Casing with controlled yield range for service in hydrogen sulphide environments

R95


Quenched and Tempered
 High strength Tubing & Casing with conntrolled yield range

T95 Type 1


Quenched and Tempered
 High strength Tubing & Casing with controlled yield range for service in hydrogen sulphide environments

C110


Quenched and Tempered
 High strength Casing with controlled yield range for service in hydrogen sulphide environments
P110
Quenched and Tempered
 High strength Tubing & Casing for high pressure service
Q125 Type 1
Quenched and Tempered
 Casing for deep well service





What is casing pipe ?

Casing  pipe is a series of steel pipes that are inserted into a drilled well to stabilize the well, prevent contaminants and water from entering the oil flow, and prevent oil from seeping into the groundwater. Casing  pipe is installed in layers with decreasing diameters and connected together to form a casing string. There are five types of casing strings: conductor, surface casing, intermediate casing, casing liner, and production casing. Steel casing pipe has a smooth wall and a minimum yield strength of 35,000 psi.Casing is used for lining the complete borehole which has been dug into the ground to procure oil.  Casing is large diameter pipe which is held in place in the borehole using cement. The diameters of casing pipe range from 4.5″ to 36″.

What is tubing pipe ?

Tubing pipe is inserted inside the wellbore through the oil well casing pipe, which helps the transportation of the hydrocarbons to the surface. It is pipe either used for transporting natural gas or crude oil to the facilities for further processing after the drilling is complete. Tubing is available in various sizes ranging from ¾” to 4 ½”.Tubing pipe is the pipe that carries oil and gas from the producing formation to the on-site surface facilities for processing. Tubing must be strong enough to resist the loads and deformations associated with production and well repair. In addition, the size of the tubing must be able to support the expected oil and gas production rate. Obviously, tubing that is too small will limit production and the subsequent economic performance of the well. However, tubing that is too large can have economic impacts beyond the cost of the tubing string itself, because tubing size affects the overall casing design of the well.

Manufacturing Process of Casing and Tubing

API Casing and Tubing Chart

Dimensions table for tubing
DN O. D. Weight W. T. End Machining Form
Steel Grade
Inch mm lb/ft kg/m Inch mm H40 J55 L80 N80 C90 P110
K55 T95
4 1/2 4.5 114.3 9.5 14.14 0.205 5.21 PS PS – – – –
10.5 15.63 0.224 5.69 – PSB – – – –
11.6 17.26 0.25 6.35 – PSLB PLB PLB PLB PLB
13.5 20.09 0.29 7.37 – – PLB PLB PLB PLB
15.1 22.47 0.337 9.56 – – – – – PLB
5 5 127 11.5 17.11 0.22 5.59 – PS – – – –
13 19.35 0.253 6.43 – PSLB – – – –
15 22.32 0.296 7.52 – PSLB PLB PLB PLBE PLB
18 26.79 0.362 9.19 – – PLB PLB PLBE PLB
21.4 31.85 0.437 11.1 – – PLB PLB PLB PLB
23.2 34.53 0.478 12.14 – – – – PLB –
24.1 35.86 0.5 12.7 – – – – PLB –
5 1/2 5.5 139.7 14 20.83 0.244 6.2 PS PS – – – –
15.5 23.07 0.275 6.98 – PSLB – – – –
17 25.3 0.304 7.72 – PSLB PLB PLB PLBE PLB
20 29.76 0.361 9.17 – – PLB PLB PLBE PLB
23 34.23 0.415 10.54 – – PLB PLB PLBE PLB
26.8 39.88 0.5 12.7 – – – – – –
29.7 44.2 0.562 14.27 – – – – – –
32.6 48.51 0.625 15.88 – – – – – –
35.3 52.53 0.687 17.45 – – – – – –
38 56.55 0.75 19.05 – – – – – –
40.5 60.27 0.812 20.62 – – – – – –
43.1 64.14 0.875 22.22 – – – – – –
6 5/8 6.625 168.28 20 29.76 0.288 7.32 PS PSLB – – – –
24 35.72 0.352 8.94 – PSLB PLB PLB PLBE PLB
28 41.67 0.417 10.59 – – PLB PLB PLBE PLB
32 47.62 0.475 12.06 – – PLB PLB PLBE PLB
7 7 177.8 17 25.3 0.231 5.87 PS – – – – –
20 29.76 0.272 6.91 PS PS – – – –
23 34.23 0.317 8.05 – PSLB PLB PLB PLBE –
26 38.69 0.362 9.19 – PSLB PLB PLB PLBE PLB
29 43.16 0.408 10.36 – – PLB PLB PLBE PLB
32 47.62 0.453 11.51 – – PLB PLB PLBE PLB
35 52.09 0.498 12.65 – – PLB PLB PLBE PLB
38 56.55 0.54 13.72 – – PLB PLB PLBE PLB
42.7 63.54 0.625 15.88 – – – – – –
46.4 69.05 0.687 17.45 – – – – – –
50.1 74.56 0.75 19.05 – – – – – –
53.6 79.77 0.812 20.62 – – – – – –
57.1 84.97 0.875 22.22 – – – – – –
7 5/8 7.625 193.68 24 35.72 0.3 7.62 PS – – – – –
26.4 39.29 0.328 8.33 – PSLB PLB PLB PLBE PLB
29.7 44.2 0.375 9.52 – – PLB PLB PLBE PLB
33.7 50.15 0.43 10.92 – – PLB PLB PLBE PLB
39 58.05 0.5 12.7 – – PLB PLB PLBE PLB
42.8 63.69 0.562 14.27 – – PLB PLB PLB PLB
45.3 67.41 0.595 15.11 – – PLB PLB PLB PLB
47.1 70.09 0.625 15.88 – – PLB PLB PLB PLB
51.2 76.19 0.687 17.45 – – – – – –
55.3 80.3 0.75 19.05 – – – – – –
8 5/8 8.625 219.08 24 35.72 0.264 6.71 – PS – – – –
28 41.62 0.304 7.72 PS – – – – –
32 47.62 0.352 8.94 PS PSLB – – – –
36 53.57 0.4 10.16 – PSLB PLB PLB PLBE PLB
40 59.53 0.45 11.43 – – PLB PLB PLBE PLB
44 65.48 0.5 12.7 – – PLB PLB PLBE PLB
49 72.92 0.557 14.15 – – PLB PLB PLBE PLB
9 5/8 9.625 244.48 32.3 48.07 0.312 7.92 PS – – – – –
36 53.57 0.352 8.94 PS PSLB – – – –
40 59.53 0.395 10.03 – PSLB PLB PLB PLBE –
43.5 64.73 0.435 11.05 – – PLB PLB PLBE PLB
47 69.94 0.472 11.99 – – PLB PLB PLBE PLB
53.5 79.62 0.545 13.84 – – PLB PLB PLBE PLB
58.4 86.91 0.595 15.11 – – PLB PLB PLB PLB
59.4 88.4 0.609 15.47 – – – – – –
64.9 96.58 0.672 17.07 – – – – – –
70.3 104.62 0.734 18.64 – – – – – –
75.6 112.5 0.797 20.24 – – – – – –
10 3/4 10.75 273.05 32.75 48.74 0.279 7.09 PS – – – – –
40.5 60.27 0.35 8.89 PS PSB – – – –
15.5 67.71 0.4 10.16 – PSB – – – –
51 75.9 0.45 11.43 – PSB PSB PSB PSBE PSB
55.5 82.59 0.495 12.57 – – PSB PSB PSBE PSB
60.7 90.33 0.545 13.84 – – – – PSBE PSB
65.7 97.77 0.595 15.11 – – – – PSB PSB
73.2 108.93 0.672 17.07 – – – – – –
79.2 117.86 0.734 18.64 – – – – – –
85.3 126.94 0.797 20.24 – – – – – –
11 3/4 11.75 42 62.5 0.333 8.46 PS – – – – –
47 69.94 0.375 20.24 – – – – – –
54 80.36 0.435 8.46 – – – – – –
60 89.29 0.489 9.53 – – – – – –
65 96.73 0.534 11.05 – – – – – –
71 105.66 0.582 14.42 – – – – – –
13 3/8 13.375 339.73 48 71.43 0.33 8.38 PS – – – – –
54.5 81.1 0.38 9.65 – PSB – – – –
61 90.78 0.43 10.92 – PSB – – – –
68 101.19 0.48 12.19 – PSB PSB PSB PSB PSB
72 107.15 0.514 13.06 – – PSB PSB PSB PSB
16 16 406.4 65 96.73 0.375 9.53 PS – – – – –
75 111.61 0.438 11.13 – PSB – – – –
84 125.01 0.495 12.57 – PSB – – – –
109 162.21 0.656 16.66 – P P P – P
18 5/8 18.625 473.08 87.5 130.21 0.435 11.05 PS PSB – – – –
20 20 508 94 139.89 0.438 11.13 PSL PSLB – – – –
106.5 158.49 0.5 12.7 – PSLB – – – –
133 197.93 0.635 16.13 – PSLB – – – –
P——Plain；S——Short-thread；L——Long-thread；B——Buttress thread；E——Extreme thread


Dimensions table for casing

DN O. D. Weight W. T. End Machining Form
Steel Grade
Inch mm lb/ft kg/m Inch mm H40 J55 L80 N80 C90 P110
K55 T95
4 1/2 4.5 114.3 9.5 14.14 0.205 5.21 PS PS – – – –
10.5 15.63 0.224 5.69 – PSB – – – –
11.6 17.26 0.25 6.35 – PSLB PLB PLB PLB PLB
13.5 20.09 0.29 7.37 – – PLB PLB PLB PLB
15.1 22.47 0.337 9.56 – – – – – PLB
5 5 127 11.5 17.11 0.22 5.59 – PS – – – –
13 19.35 0.253 6.43 – PSLB – – – –
15 22.32 0.296 7.52 – PSLB PLB PLB PLBE PLB
18 26.79 0.362 9.19 – – PLB PLB PLBE PLB
21.4 31.85 0.437 11.1 – – PLB PLB PLB PLB
23.2 34.53 0.478 12.14 – – – – PLB –
24.1 35.86 0.5 12.7 – – – – PLB –
5 1/2 5.5 139.7 14 20.83 0.244 6.2 PS PS – – – –
15.5 23.07 0.275 6.98 – PSLB – – – –
17 25.3 0.304 7.72 – PSLB PLB PLB PLBE PLB
20 29.76 0.361 9.17 – – PLB PLB PLBE PLB
23 34.23 0.415 10.54 – – PLB PLB PLBE PLB
26.8 39.88 0.5 12.7 – – – – – –
29.7 44.2 0.562 14.27 – – – – – –
32.6 48.51 0.625 15.88 – – – – – –
35.3 52.53 0.687 17.45 – – – – – –
38 56.55 0.75 19.05 – – – – – –
40.5 60.27 0.812 20.62 – – – – – –
43.1 64.14 0.875 22.22 – – – – – –
6 5/8 6.625 168.28 20 29.76 0.288 7.32 PS PSLB – – – –
24 35.72 0.352 8.94 – PSLB PLB PLB PLBE PLB
28 41.67 0.417 10.59 – – PLB PLB PLBE PLB
32 47.62 0.475 12.06 – – PLB PLB PLBE PLB
7 7 177.8 17 25.3 0.231 5.87 PS – – – – –
20 29.76 0.272 6.91 PS PS – – – –
23 34.23 0.317 8.05 – PSLB PLB PLB PLBE –
26 38.69 0.362 9.19 – PSLB PLB PLB PLBE PLB
29 43.16 0.408 10.36 – – PLB PLB PLBE PLB
32 47.62 0.453 11.51 – – PLB PLB PLBE PLB
35 52.09 0.498 12.65 – – PLB PLB PLBE PLB
38 56.55 0.54 13.72 – – PLB PLB PLBE PLB
42.7 63.54 0.625 15.88 – – – – – –
46.4 69.05 0.687 17.45 – – – – – –
50.1 74.56 0.75 19.05 – – – – – –
53.6 79.77 0.812 20.62 – – – – – –
57.1 84.97 0.875 22.22 – – – – – –
7 5/8 7.625 193.68 24 35.72 0.3 7.62 PS – – – – –
26.4 39.29 0.328 8.33 – PSLB PLB PLB PLBE PLB
29.7 44.2 0.375 9.52 – – PLB PLB PLBE PLB
33.7 50.15 0.43 10.92 – – PLB PLB PLBE PLB
39 58.05 0.5 12.7 – – PLB PLB PLBE PLB
42.8 63.69 0.562 14.27 – – PLB PLB PLB PLB
45.3 67.41 0.595 15.11 – – PLB PLB PLB PLB
47.1 70.09 0.625 15.88 – – PLB PLB PLB PLB
51.2 76.19 0.687 17.45 – – – – – –
55.3 80.3 0.75 19.05 – – – – – –
8 5/8 8.625 219.08 24 35.72 0.264 6.71 – PS – – – –
28 41.62 0.304 7.72 PS – – – – –
32 47.62 0.352 8.94 PS PSLB – – – –
36 53.57 0.4 10.16 – PSLB PLB PLB PLBE PLB
40 59.53 0.45 11.43 – – PLB PLB PLBE PLB
44 65.48 0.5 12.7 – – PLB PLB PLBE PLB
49 72.92 0.557 14.15 – – PLB PLB PLBE PLB
9 5/8 9.625 244.48 32.3 48.07 0.312 7.92 PS – – – – –
36 53.57 0.352 8.94 PS PSLB – – – –
40 59.53 0.395 10.03 – PSLB PLB PLB PLBE –
43.5 64.73 0.435 11.05 – – PLB PLB PLBE PLB
47 69.94 0.472 11.99 – – PLB PLB PLBE PLB
53.5 79.62 0.545 13.84 – – PLB PLB PLBE PLB
58.4 86.91 0.595 15.11 – – PLB PLB PLB PLB
59.4 88.4 0.609 15.47 – – – – – –
64.9 96.58 0.672 17.07 – – – – – –
70.3 104.62 0.734 18.64 – – – – – –
75.6 112.5 0.797 20.24 – – – – – –
10 3/4 10.75 273.05 32.75 48.74 0.279 7.09 PS – – – – –
40.5 60.27 0.35 8.89 PS PSB – – – –
15.5 67.71 0.4 10.16 – PSB – – – –
51 75.9 0.45 11.43 – PSB PSB PSB PSBE PSB
55.5 82.59 0.495 12.57 – – PSB PSB PSBE PSB
60.7 90.33 0.545 13.84 – – – – PSBE PSB
65.7 97.77 0.595 15.11 – – – – PSB PSB
73.2 108.93 0.672 17.07 – – – – – –
79.2 117.86 0.734 18.64 – – – – – –
85.3 126.94 0.797 20.24 – – – – – –
11 3/4 11.75 42 62.5 0.333 8.46 PS – – – – –
47 69.94 0.375 20.24 – – – – – –
54 80.36 0.435 8.46 – – – – – –
60 89.29 0.489 9.53 – – – – – –
65 96.73 0.534 11.05 – – – – – –
71 105.66 0.582 14.42 – – – – – –
13 3/8 13.375 339.73 48 71.43 0.33 8.38 PS – – – – –
54.5 81.1 0.38 9.65 – PSB – – – –
61 90.78 0.43 10.92 – PSB – – – –
68 101.19 0.48 12.19 – PSB PSB PSB PSB PSB
72 107.15 0.514 13.06 – – PSB PSB PSB PSB
16 16 406.4 65 96.73 0.375 9.53 PS – – – – –
75 111.61 0.438 11.13 – PSB – – – –
84 125.01 0.495 12.57 – PSB – – – –
109 162.21 0.656 16.66 – P P P – P
18 5/8 18.625 473.08 87.5 130.21 0.435 11.05 PS PSB – – – –
20 20 508 94 139.89 0.438 11.13 PSL PSLB – – – –
106.5 158.49 0.5 12.7 – PSLB – – – –
133 197.93 0.635 16.13 – PSLB – – – –
P——Plain；S——Short-thread；L——Long-thread；B——Buttress thread；E——Extreme thread


Our casing and tubing are not only manufactured strictly in accordance with API standards, but we also develop proprietary grades for special application environments such as sour, high collapse, chrome and CRA. With these proprietary grades, we are able to provide the best solution for each customer's specific well conditions. All of our products are produced in accordance with the most stringent quality standards. Our operations have been globally ISO 9001 certified, implement a unified quality policy, and adopt a rigorous quality management system. 

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Recruiting Agents, contact: info@baowi-steel.com

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