Expansion Joints installed in piping systems that are anchored on both sides of connectors need no control rods, providing piping movements are within the tabulated allowables. Expansion joints installed in unanchored piping or connected to isolated equipment must have control rods; those control rods must be properly set so that allowable movements are not exceeded. The number of control rods is determined by the maximum working pressure of the pipeline, not the maximum pressure rating of the joint. Use the convenient chart to the right to specify. Control rods are designed for a 3:1 safety factor as is; please use accordingly. For example, if a 24” 452 joint is installed in a pipeline with a maximum pressure of 120 psig, 3 control rods are required. If the maximum pressure of the pipeline is 220 psig, 5 control rods are required.