Garlock PTFE expansion joints and couplings have pressure ratings high enough to handle most applications. As the pipe size gets larger, Garlock increases the bellows thickness and the strength of the reinforcing rings to compensate for the change in internal forces. This permits the same high pressure. Body Material, Tube Material, and Cover Material are all PTFE on SURELINK expansion joints. Vacuum (In.HG) and Pressure (psi) are both Application Dependent. Control units are recommended for most applications to prevent damage to the expansion joint from excessive pipe movement (sold separately).