the low pressure seal arrangement for sealing a space defined by an inner diameter of a pipe and a rod slidably disposed with the pipe . the low pressure seal includes a sealing insert of reusable , noncorrosive , shape retentive , resilient , boron - resistant , flexible polymeric resin with an axial passage for receiving the tubular rod . the sealing insert combines the functions of a gasket and a stopper , the sealing insert having a hub end of a larger diameter than the pipe , preventing the sealing insert from slipping into the pipe . the sealing insert is installed by hand without tools and resists a pressure of at least 350 psi . the sealing insert may be removed and reused , reducing the amount of radioactive waste generated by the nuclear reactor .