CASING COUPLINGS AND THREAD ELEMENTS
A coupling is a short piece of pipe used to connect the two ends, pin and box. of the casing. Casing couplings are designed to sustain high tensile load while
Table 1.7: Strengths of non-API steel grades.
Minima]
Ultimate
Yield Strength Tensile Minimal*
Non-API (psi) Strength Elongation
Grade Manufacturer Minimum Maximum (psi) (Ус)
|
S-80 |
Lone Star Steel |
75.000 " |
— |
75.000 |
20.0 |
|
55.000 f |
— |
||||
|
Mod. N-80 |
Mannesmann |
80.000 |
95.000 |
100.000 |
24.0 |
|
C-90 1 |
Mannesmann |
90.000 |
105.000 |
120.000 |
26.0 |
|
SS-95 |
Lone Star Steel |
95.000 — |
— |
95.000 |
18.0 |
|
75.000 + |
— |
||||
|
S00-95 |
Mannesmann |
95.000 |
110.000 |
110.000 |
20.0 |
|
S-95 |
Lone Star Steel |
95,000 " |
— |
110.000 |
16.0 |
|
92,000 1 |
— |
||||
|
S00-125 |
Mannesmann |
125.000 |
150.000 |
135.000 |
18.0 |
|
S00-140 |
Mannesmann |
140.000 |
165.000 |
150.000 |
17.0 |
|
V-I50 |
U. S. Steel |
150.000 |
180.000 |
160.000 |
14.0 |
|
S00-155 |
Mannesmann |
155.000 |
180.000 |
165.000 |
20.0 |
* Test specimen with area greater than 0.75 sq in.
** Circumferential, t Longitudinal
+ Maximal ultimate tensile strength of 120.000 psi.
at the same time providing pressure containment from both net internal and external pressures. Their ability to resist tension and contain pressure depends primarily on the type of threads cut on the coupling and at the pipe ends. With the exception of a growing number of proprietary couplings, the configurations and specifications of the couplings are standardized by API (API RP 5B1. 1988).