Page 183 - Tyco-Grooved-Fire-Protection-Products-Installation-Handbook

SYSTEM DESIGN 181 Rotational Movement
Grinnell Flexible Couplings are suitable for use in seismic as well as other applications. The inherent capability of the flexible coupling to allow for linear movement, angular deflection, and rotational movement, make it an excellent choice for reducing stresses in a piping system.
For mining applications where pipe needs to be rotated, the system should be depressurized. The pipe couplings bolts/nuts can be loos- ened, pipe rotated and the bolts/nuts re-tightened and the system restored to service.
Even distribution of pipe wear can be achieved with this method on inner surface of the pipe.
NOTE
Precautions are necessary to monitor pipe wall thickness to evaluate pressure capability of the pipe with reduced wall density.
Linear Movement
The inherent flexibility of the coupling must be consider when deciding on support arrangements for the pipe system as movement can occur in more than one plane (linear movement, angular deflection, and rota- tional movement.
Upon system pressurization, each pipe end within the flexible cou- plings will expand to the maximum published value. The coupling keys make contact with the face of the groove and restrain the joint. In piping systems, this movement will be accumulative.