OCTG casing pipe, which stands for "Oil Country Tubular Goods," is a category of seamless steel products, including drill pipes, casing and tubing, that are essential for drilling and producing oil and gas. Casing pipes specifically are used to line the borehole, preventing the wellbore from collapsing and isolating different subsurface layers. These pipes are constructed from high-strength steel grades to endure the extreme pressures, temperatures, and corrosive conditions typically found in oil and gas wells. They are vital components in maintaining the integrity of wells during exploration and production activities.
API SPEC 5CT establishes the standard sizing system for tubing and casing used in oil and gas wells, covering a defined range of steel pipe dimensions. According to this specification, OCTG casing is commonly produced in diameters from 4 1/2" to 20", while tubing is available in smaller sizes, typically between 1.05" and 4 1/2".
Casing Pipe Size Chart
The size of casing pipes varies depending on their application in the oil, gas, and water drilling industries. Here's a general casing pipe size chart with common dimensions, based on API 5CT standards:
|
Lables
|
Outside
|
Nominal
|
Wall
|
Inside
|
Drift
|
Calculated mass C
|
|
diameter
|
diameter
|
thickness
|
diameter
|
diameter
|
Plain End
|
Mass gain or loss due to end finishing (lb)
|
|
|
|
|
|
|
Round thread
|
Buttress thread
|
|
1
|
2
|
D (in)
|
lb/ft
|
t (in)
|
d (in)
|
in
|
lb/ft
|
Short
|
Long
|
RC
|
SCC
|
|
1
|
2
|
3
|
4
|
5
|
6
|
7
|
8
|
9
|
10
|
11
|
12
|
|
4 1/2
|
9.5
|
4.5
|
9.5
|
0.205
|
4.09
|
3.965
|
9.41
|
4.2
|
|
|
|
|
4 1/2
|
10.5
|
4.5
|
10.5
|
0.224
|
4.052
|
3.927
|
10.24
|
3.8
|
|
5
|
2.56
|
|
4 1/2
|
11.6
|
4.5
|
11.6
|
0.25
|
4
|
3.875
|
11.36
|
3.4
|
3.8
|
4.6
|
2.16
|
|
4 1/2
|
13.5
|
4.5
|
13.5
|
0.29
|
3.92
|
3.795
|
13.05
|
|
3.2
|
4
|
1.56
|
|
4 1/2
|
15.1
|
4.5
|
15.1
|
0.337
|
3.826
|
3.701
|
15
|
|
2.8
|
3.2
|
0.76
|
|
5
|
11.5
|
5
|
11.5
|
0.22
|
4.56
|
4.435
|
11.24
|
5.4
|
|
|
|
|
5
|
13
|
5
|
13
|
0.253
|
4.494
|
4.369
|
12.84
|
4.8
|
5.8
|
6.6
|
2.42
|
|
5
|
15
|
5
|
15
|
0.296
|
4.408
|
4.283
|
14.88
|
4.2
|
5.2
|
5.8
|
1.62
|
|
5
|
18
|
5
|
18
|
0.362
|
4.276
|
4.151
|
17.95
|
|
4.2
|
4.4
|
0.22
|
|
5
|
21.4
|
5
|
21.4
|
0.437
|
4.126
|
4.001
|
21.32
|
|
2.95
|
2.46
|
-1.72
|
|
5
|
23.2
|
5
|
23.2
|
0.478
|
4.044
|
3.919
|
23.11
|
|
2.3
|
2.05
|
-2.09
|
|
5
|
24.1
|
5
|
24.1
|
0.5
|
4
|
3.875
|
24.05
|
|
1.95
|
1.24
|
-2.94
|
|
5 1/2
|
14
|
5.5
|
14
|
0.244
|
5.015
|
4.887
|
13.71
|
5.4
|
|
|
|
|
5 1/2
|
15.5
|
5.5
|
15.5
|
0.275
|
4.95
|
4.825
|
15.36
|
4.8
|
5.8
|
6.4
|
2.1
|
|
5 1/2
|
17
|
5.5
|
17
|
0.304
|
4.892
|
4.767
|
16.89
|
4.4
|
5.4
|
5.8
|
1.5
|
|
5 1/2
|
20
|
5.5
|
20
|
0.361
|
4.778
|
4.653
|
19.83
|
|
4.4
|
4.6
|
0.3
|
|
5 1/2
|
23
|
5.5
|
23
|
0.415
|
4.67
|
4.545
|
22.56
|
|
3.2
|
3.4
|
0.9
|
|
5 1/2
|
26.8
|
5.5
|
26.8
|
0.5
|
4.5
|
4.375
|
26.72
|
|
|
|
|
|
5 1/2
|
29.7
|
5.5
|
29.7
|
0.562
|
4.376
|
4.251
|
29.67
|
|
|
|
|
|
5 1/2
|
32.6
|
5.5
|
32.6
|
0.625
|
4.25
|
4.125
|
32.57
|
|
|
|
|
|
5 1/2
|
35.3
|
5.5
|
35.3
|
0.687
|
4.126
|
4.001
|
35.35
|
|
|
|
|
|
5 1/2
|
38
|
5.5
|
38
|
0.75
|
4
|
3.875
|
38.08
|
|
|
|
|
|
5 1/2
|
40.5
|
5.5
|
40.5
|
0.812
|
3.876
|
3.751
|
40.69
|
|
|
|
|
|
5 1/2
|
43.1
|
5.5
|
43.1
|
0.875
|
3.75
|
3.625
|
43.26
|
|
|
|
|
|
6 5/8
|
20
|
6.625
|
20
|
0.288
|
6.049
|
5.924
|
19.51
|
11
|
13.6
|
14.4
|
2.38
|
|
6 5/8
|
24
|
6.625
|
24
|
0.352
|
5.921
|
5.796
|
23.6
|
9.6
|
12
|
12.6
|
0.58
|
|
6 5/8
|
28
|
6.625
|
28
|
0.417
|
5.791
|
5.666
|
27.67
|
|
10.2
|
10.6
|
-1.42
|
|
6 5/8
|
32
|
6.625
|
32
|
0.475
|
5.675
|
5.55
|
31.23
|
|
8.8
|
9
|
-3.02
|
|
7
|
17
|
7
|
17
|
0.231
|
6.538
|
6.413
|
16.72
|
10
|
|
|
|
|
7
|
20
|
7
|
20
|
0.272
|
6.456
|
6.331
|
19.56
|
9.4
|
|
|
|
|
7
|
23
|
7
|
23
|
0.317
|
6.366
|
6.25
|
22.65
|
8
|
10.4
|
11
|
1.6
|
|
7
|
23
|
7
|
23
|
0.317
|
6.366
|
6.241
|
22.65
|
8
|
10.4
|
11
|
1.6
|
|
7
|
26
|
7
|
26
|
0.362
|
6.276
|
6.151
|
25.69
|
7.2
|
9.4
|
9.6
|
0.2
|
|
7
|
29
|
7
|
29
|
0.408
|
6.184
|
6.059
|
28.75
|
|
8
|
8.2
|
1.2
|
|
7
|
32
|
7
|
32
|
0.453
|
6.094
|
6
|
31.7
|
|
6.6
|
6.8
|
2.6
|
|
7
|
32
|
7
|
32
|
0.453
|
6.094
|
5.969
|
31.7
|
|
6.6
|
6.8
|
2.6
|
|
7
|
35
|
7
|
35
|
0.498
|
6.004
|
5.879
|
34.61
|
|
5.6
|
5.6
|
3.8
|
|
7
|
38
|
7
|
38
|
0.54
|
5.92
|
5.795
|
37.29
|
|
4.4
|
4.2
|
5.2
|
|
7
|
42.7
|
7
|
42.7
|
0.625
|
5.75
|
5.625
|
42.59
|
|
|
|
|
|
7
|
46.4
|
7
|
46.4
|
0.687
|
5.625
|
5.5
|
46.36
|
|
|
|
|
|
7
|
50.1
|
7
|
50.1
|
0.75
|
5.5
|
5.375
|
50.11
|
|
|
|
|
|
7
|
53.6
|
7
|
53.6
|
0.812
|
5.376
|
5.251
|
53.71
|
|
|
|
|
|
7
|
57.1
|
7
|
57.1
|
0.875
|
5.25
|
5.125
|
57.29
|
|
|
|
|
|
7 5/8
|
24
|
7.625
|
24
|
0.3
|
7.025
|
6.9
|
23.49
|
15.8
|
|
|
|
|
7 5/8
|
26.4
|
7.625
|
26.4
|
0.328
|
6.969
|
6.844
|
25.59
|
15.2
|
19
|
20.6
|
6.21
|
|
7 5/8
|
29.7
|
7.625
|
29.7
|
0.375
|
6.875
|
6.75
|
29.06
|
|
17.4
|
18.8
|
4.41
|
|
7 5/8
|
33.7
|
7.625
|
33.7
|
0.43
|
6.765
|
6.64
|
33.07
|
|
15.8
|
17
|
2.61
|
|
7 5/8
|
39
|
7.625
|
39
|
0.5
|
6.625
|
6.5
|
38.08
|
|
13.6
|
14.6
|
0.21
|
|
7 5/8
|
42.8
|
7.625
|
42.8
|
0.562
|
6.501
|
6.376
|
42.43
|
|
12.01
|
11.39
|
-3.01
|
|
7 5/8
|
45.3
|
7.625
|
45.3
|
0.595
|
6.435
|
6.31
|
44.71
|
|
11.04
|
11.04
|
-3.36
|
|
7 5/8
|
47.1
|
7.625
|
47.1
|
0.625
|
6.375
|
6.25
|
46.77
|
|
10.16
|
9.23
|
-5.17
|
|
7 5/8
|
51.2
|
7.625
|
51.2
|
0.687
|
6.251
|
6.126
|
50.95
|
|
|
|
|
|
7 5/8
|
55.3
|
7.625
|
55.3
|
0.75
|
6.125
|
6
|
55.12
|
|
|
|
|
|
7 3/4
|
46.1
|
7.75
|
46.1
|
0.595
|
6.56
|
6.5
|
45.51
|
|
|
|
|
|
7 3/4
|
46.1
|
7.75
|
46.1
|
0.595
|
6.56
|
6.435
|
45.51
|
|
|
|
|
|
8 5/8
|
24
|
8.625
|
24
|
0.264
|
8.097
|
7.972
|
23.6
|
23.6
|
|
|
|
|
8 5/8
|
28
|
8.625
|
28
|
0.304
|
8.017
|
7.892
|
27.04
|
22.2
|
|
|
|
|
8 5/8
|
32
|
8.625
|
32
|
0.352
|
7.921
|
7.875
|
31.13
|
20.8
|
27.6
|
28.3
|
6.03
|
|
8 5/8
|
32
|
8.625
|
32
|
0.352
|
7.921
|
7.796
|
31.13
|
20.8
|
27.6
|
28.2
|
6.03
|
|
8 5/8
|
36
|
8.625
|
36
|
0.4
|
7.825
|
7.7
|
35.17
|
19.4
|
25.6
|
26.2
|
4.03
|
|
8 5/8
|
40
|
8.625
|
40
|
0.45
|
7.725
|
7.625
|
39.33
|
|
23.8
|
24.2
|
2.03
|
|
8 5/8
|
40
|
8.625
|
40
|
0.45
|
7.725
|
7.6
|
39.33
|
|
23.8
|
24.2
|
2.03
|
|
8 5/8
|
44
|
8.625
|
44
|
0.5
|
7.625
|
7.5
|
43.43
|
|
21.8
|
22.2
|
0.03
|
|
8 5/8
|
49
|
8.625
|
49
|
0.557
|
7.511
|
7.286
|
48.04
|
|
19.6
|
19.8
|
-2.37
|
|
9 5/8
|
32.3
|
9.625
|
32.3
|
0.312
|
9.001
|
8.845
|
31.06
|
24.4
|
|
|
|
|
9 5/8
|
36
|
9.625
|
36
|
0.352
|
8.921
|
8.876
|
34.89
|
23
|
32
|
31
|
6.48
|
|
9 5/8
|
40
|
9.625
|
40
|
0.395
|
8.835
|
8.75
|
38.97
|
21.4
|
30
|
29
|
4.48
|
|
9 5/8
|
40
|
9.625
|
40
|
0.395
|
8.835
|
8.679
|
38.97
|
21.4
|
30
|
29
|
4.48
|
|
9 5/8
|
43.5
|
9.625
|
43.5
|
0.435
|
8.755
|
8.599
|
42.73
|
|
28.2
|
27.2
|
2.68
|
|
9 5/8
|
47
|
9.625
|
47
|
0.472
|
8.681
|
8.525
|
46.18
|
|
26.6
|
25.6
|
1.08
|
|
9 5/8
|
53.5
|
9.625
|
53.5
|
0.545
|
8.535
|
8.5
|
52.9
|
|
23.4
|
22.4
|
-2.12
|
|
9 5/8
|
53.5
|
9.625
|
53.5
|
0.545
|
8.535
|
8.379
|
52.9
|
|
23.4
|
22.4
|
-2.12
|
|
9 5/8
|
58.4
|
9.625
|
58.4
|
0.595
|
8.435
|
8.375
|
57.44
|
|
21.5
|
20.13
|
-4.4
|
|
9 5/8
|
58.4
|
9.625
|
58.4
|
0.595
|
8.435
|
8.279
|
57.44
|
|
21.5
|
20.13
|
-4.4
|
|
9 5/8
|
59.4
|
9.625
|
59.4
|
0.609
|
8.407
|
8.251
|
58.7
|
|
|
|
|
|
9 5/8
|
64.9
|
9.625
|
64.9
|
0.672
|
8.281
|
8.125
|
64.32
|
|
|
|
|
|
9 5/8
|
70.3
|
9.625
|
70.3
|
0.734
|
8.157
|
8.001
|
69.76
|
|
|
|
|
|
9 5/8
|
75.6
|
9.625
|
75.6
|
0.797
|
8.031
|
7.875
|
75.21
|
|
|
|
|
|
10 3/4
|
32.75
|
10.75
|
32.75
|
0.279
|
10.192
|
10.036
|
31.23
|
29
|
|
|
|
|
10 3/4
|
40.5
|
10.75
|
40.5
|
0.35
|
10.05
|
9.894
|
38.91
|
26.4
|
|
34.4
|
7.21
|
|
10 3/4
|
45.5
|
10.75
|
45.5
|
0.4
|
9.95
|
9.875
|
44.26
|
24.4
|
|
31.8
|
4.61
|
|
10 3/4
|
45.5
|
10.75
|
45.5
|
0.4
|
9.95
|
9.794
|
44.26
|
24.4
|
|
31.8
|
4.61
|
|
10 3/4
|
51
|
10.75
|
51
|
0.45
|
9.85
|
9.694
|
49.55
|
22.6
|
|
29.4
|
2.21
|
|
10 3/4
|
55.5
|
10.75
|
55.5
|
0.495
|
9.76
|
9.625
|
54.26
|
20.8
|
|
27
|
-0.19
|
|
10 3/4
|
55.5
|
10.75
|
55.5
|
0.495
|
9.76
|
9.604
|
54.26
|
20.8
|
|
27
|
-0.19
|
|
10 3/4
|
60.7
|
10.75
|
60.7
|
0.545
|
9.66
|
9.504
|
59.45
|
18.8
|
|
24.4
|
|
|
10 3/4
|
65.7
|
10.75
|
65.7
|
0.595
|
9.56
|
9.404
|
64.59
|
16.8
|
|
22
|
|
|
10 3/4
|
73.2
|
10.75
|
73.2
|
0.672
|
9.406
|
9.25
|
72.4
|
|
|
|
|
|
10 3/4
|
79.2
|
10.75
|
79.2
|
0.734
|
9.282
|
9.126
|
78.59
|
|
|
|
|
|
10 3/4
|
85.3
|
10.75
|
85.3
|
0.797
|
9.156
|
9
|
84.8
|
|
|
|
|
|
11 3/4
|
42
|
11.75
|
42
|
0.333
|
11.084
|
11
|
40.64
|
29.6
|
|
|
|
|
11 3/4
|
42
|
11.75
|
42
|
0.333
|
11.084
|
10.928
|
40.64
|
29.6
|
|
|
|
|
11 3/4
|
47
|
11.75
|
47
|
0.375
|
11
|
10.844
|
45.6
|
27.6
|
|
35.8
|
|
|
11 3/4
|
54
|
11.75
|
54
|
0.435
|
10.88
|
10.724
|
52.62
|
25
|
|
32.4
|
|
|
11 3/4
|
60
|
11.75
|
60
|
0.489
|
10.772
|
10.625
|
58.87
|
22.6
|
|
29.6
|
|
|
11 3/4
|
60
|
11.75
|
60
|
0.489
|
10.772
|
10.616
|
58.87
|
22.6
|
|
29.6
|
|
|
11 3/4
|
65
|
11.75
|
65
|
0.534
|
10.682
|
10.625
|
64.03
|
|
|
|
|
|
11 3/4
|
65
|
11.75
|
65
|
0.534
|
10.682
|
10.625
|
64.03
|
|
|
|
|
|
11 3/4
|
71
|
11.75
|
71
|
0.582
|
10.586
|
10.43
|
69.48
|
|
|
|
|
|
13 3/8
|
48
|
13.375
|
48
|
0.33
|
12.715
|
12.559
|
46.02
|
33.2
|
|
|
|
|
13 3/8
|
54.5
|
13.375
|
54.5
|
0.38
|
12.615
|
12.459
|
52.79
|
30.8
|
|
40.2
|
|
|
13 3/8
|
61
|
13.375
|
61
|
0.43
|
12.515
|
12.359
|
59.5
|
28.4
|
|
36.8
|
|
|
13 3/8
|
68
|
13.375
|
68
|
0.48
|
12.415
|
12.259
|
66.17
|
25.8
|
|
33.6
|
|
|
13 3/8
|
72
|
13.375
|
72
|
0.514
|
12.347
|
12.25
|
70.67
|
24.2
|
|
31.6
|
|
|
13 3/8
|
72
|
13.375
|
72
|
0.514
|
12.347
|
12.191
|
70.67
|
24.2
|
|
31.6
|
|
|
16
|
65
|
16
|
65
|
0.375
|
15.25
|
15.062
|
62.64
|
42.6
|
|
|
|
|
16
|
75
|
16
|
75
|
0.438
|
15.124
|
14.936
|
72.86
|
38.2
|
|
45.6
|
|
|
16
|
84
|
16
|
84
|
0.495
|
15.01
|
14.822
|
82.05
|
34.2
|
|
39.6
|
|
|
16
|
109
|
16
|
109
|
0.656
|
14.688
|
14.5
|
107.6
|
|
|
|
|
|
18 5/8
|
87.5
|
18.625
|
87.5
|
0.435
|
17.755
|
17.567
|
84.59
|
73.6
|
|
86.4
|
|
|
20
|
94
|
20
|
94
|
0.438
|
19.124
|
18.936
|
91.59
|
47
|
61.2
|
54.8
|
|
|
20
|
106.5
|
20
|
106.5
|
0.5
|
19
|
18.812
|
104.23
|
41.6
|
54.8
|
48.4
|
|
|
20
|
133
|
20
|
133
|
0.635
|
18.73
|
18.542
|
131.45
|
30
|
40.6
|
35.2
|
|
Key Notes on Casing Sizes:
-
OD (Outer Diameter): The external diameter of the casing pipe. It determines the size of the hole required for installation.
-
Weight (lbs/ft): Describes the linear weight of the casing, which varies based on wall thickness and steel grade.
-
Wall Thickness: Affects the casing's ability to withstand pressure and collapse forces.
-
ID (Inner Diameter): Impacts the flow capacity of the well.
If you are considering casing pipes for a specific application, ensure you check compatibility with your drilling equipment and project requirements.
Steel Pipe Dimension 3 elements
A complete description for steel pipe dimension includes outer diameter (OD), wall thickness (WT), pipe length (Normally 20 ft 6 meter, or 40 ft 12 meters).Through these elements we could calculate the pipe weight, how much pressure the pipe could bear, and the cost per foot or per meter.
So that’s why we always need to know the correct pipe size. BAOWI SteelWe provide all kinds of oil pipes and casings. If you need, please contact us.
Steel Casing Pipe FAQ (Quick Guide)
What are the most common steel casing pipe sizes?
Common nominal outside diameters include 4 1/2, 5, 5 1/2, 7, 9 5/8, 10 3/4, 13 3/8, and 20 inches. The suitable size depends on the well design, required clearances, and applicable product specification.
How do you calculate the inside diameter of casing pipe?
For nominal dimensions, subtract twice the wall thickness from the outside diameter: ID = OD − (2 × WT). This calculation gives the nominal pipe-body ID, not the drift diameter or necessarily the minimum actual clearance.
Does a larger casing pipe always have a thicker wall?
No. Outside diameter and wall thickness are separate dimensions. A given casing OD can be available in multiple nominal weights and wall thicknesses, depending on the applicable specification and product availability.
What does casing pipe weight per foot mean?
Weight per foot is the nominal reference weight for one foot of casing pipe, commonly expressed in lb/ft. It helps with string-weight and logistics calculations. Buyers should check whether a quoted value refers to pipe-body weight or includes connection-related weight effects.
What is the difference between casing pipe ID and drift diameter?
ID describes the internal diameter of the pipe body. Drift diameter refers to the minimum internal clearance verified using a specified drift mandrel and applicable requirements. Drift values should be checked separately rather than inferred from nominal ID alone.
Which API standard applies to oil well casing pipe?
API Specification 5CT is a principal specification for casing and tubing used in the petroleum and natural gas industries. Buyers should confirm the applicable edition, grade, connection, inspection requirements, and project-specific conditions rather than relying on the standard number alone.
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