US Patent 7118137 Testable pipe joint

A locking ring-type pipe joint has a spigot ring provided on a first pipe section, a bell ring provided on a second pipe section, and a locking ring that may be contracted to engage the spigot ring to the bell ring. First and second circumferential grooves formed in the spigot ring are configured to receive a test gasket and a pipe seal gasket respectively. An annular test space between the gaskets is in closed connection with a pressure port, whereby the pressure seal of the pipe seal gasket may be evaluated after the pipe sections are joined and prior to activating the joint restraint feature, installing the next pipe, and back-filling the pipe sections.