API 5CT N80 casing is a high-strength oil well tubing, including N80-1 and N80-Q. The chemical composition and mechanical properties of these two types are exactly the same, but the heat treatment is different. During heat treatment, N80-1 steel adopts normalizing + tempering treatment, and N80Q steel adopts quenching + tempering treatment. Therefore, the collapse strength and internal pressure strength of N80Q are higher than those of N80-1. The minimum yield strength of N80 casing exceeds 758MPa, and the minimum tensile strength exceeds 689MPa, and it is mainly used in oil & gas, coalbed methane exploitation and geothermal wells.
API 5CT N80 Tolerance:
|
Item
|
Allowable tolerance
|
|
Outer diameter
|
Pipe body
|
D≤101.60mm±0.79mm
|
|
D≥114.30mm+1.0%
|
|
-0.5%
|
|
Wall thickness
|
-12.5%
|
|
Weight
|
Single piece
|
+6.5%+3.5%
|
|
Total weight
|
-1.75
|
API N80 Casing Size Chart:
|
Outer Diameter
|
Wall Thickness
|
Weight
|
Grade
|
Threaded
|
Length
|
|
in
|
mm
|
kg/m
|
lb/ft
|
|
4 1/2″
|
114.3
|
14.14-22.47
|
9.50-11.50
|
N80
|
LTC/STC/BTC
|
R1/R2/R3
|
|
5″
|
127
|
17.11-35.86
|
11.50-24.10
|
N80
|
LTC/STC/BTC
|
R1/R2/R3
|
|
5 1/2″
|
139.7
|
20.83-34.23
|
14.00-23.00
|
N80
|
LTC/STC/BTC
|
R1/R2/R3
|
|
6 5/8″
|
168.28
|
29.76-35.72
|
20.00-24.00
|
N80
|
LTC/STC/BTC
|
R1/R2/R3
|
|
7″
|
177.8
|
25.30-56.55
|
17.00-38.00
|
N80
|
LTC/STC/BTC
|
R1/R2/R3
|
|
7 5/8″
|
193.68
|
35.72-63.69
|
24.00-42.80
|
N80
|
LTC/STC/BTC
|
R1/R2/R3
|
|
8 5/8″
|
219.08
|
35.72-72.92
|
24.00-49.00
|
N80
|
LTC/STC/BTC
|
R1/R2/R3
|
|
9 5/8″
|
244.48
|
48.07-86.91
|
32.30-58.40
|
N80
|
LTC/STC/BTC
|
R1/R2/R3
|
|
10 3/4″
|
273.05
|
48.73-97.77
|
32.75-65.70
|
N80
|
LTC/STC/BTC
|
R1/R2/R3
|
|
11 3/4″
|
298.45
|
62.50-89.29
|
42.00-60.00
|
N80
|
LTC/STC/BTC
|
R1/R2/R3
|
|
13 3/8″
|
339.72
|
71.43-107.15
|
48.00-72.00
|
N80
|
LTC/STC/BTC
|
R1/R2/R3
|
Inspection of N80 Casing Pipe:
- Physical properties/ size and surface inspection
- Hydrostatic
- Drifting test
- Electromagnetic
- Ultrasonic
- Physical andchemical analysis
- Hardness and pressure test.
- NDT and pressure test and third partycertification
API 5CT N80 Casing Packaging:
According to the regulations of SY/T6194-96, the domestic API 5CT N80 casing should be bound with steel wire or steel belt. The exposed part of the thread of each casing and its coupling should be screwed with a protective ring to protect the thread well.
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