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Completion Equipment 103
Figure 3.13 API long threaded and coupled connection.
• Part of the thread is exposed on the internal face of the connection,
and can induce turbulence (Fig. 3.13).
3.3.2 Premium connections
Premium connections use a metal-to-metal seal face to ensure a gas-
tight seal. The thread provides mechanical strength, and thread geom-
etry is designed to allow easy make up and break out. Many connec-
tions incorporate a torque shoulder to reduce compression loading on
the threads. Most premium connections are matched to the pipe body
yield in tension, as well as burst and collapse limits. Although most
premium connections are matched to pipe body yield when under
compression loads, a significant minority are weaker in compression
than the base pipe. Completion engineers need to be aware of these
limitations, and ensure they are included in stress analysis calculations.
Failure to do so could compromise the integrity of the production
tubing. ISO standard 13679 details testing protocols for tubing con-
nections (Fig. 3.14). 3
