Control Rods Unit
The flexible rubber sleeves of expansion joints, filled arch or open arch construction must be installed in piping systems that are properly anchored so that the flexible sleeves may not be subjected to compression or elongation of piping movement.
If axial forces can act in the system to compress or elongate the rubber sleeve, control rods units will be required to prevent axial movement. In general, control rods units are always recommended as an additional safety factor, preventing damage to the rubber sleeve and associated equipment.