Patent ID: 6957567

Claim:
A system for controlled application of fluid pressure to a load in the form of a pipe closed at its ends to pressure test the pipe, said system, comprising: at least two pressure converters each having an output side connectable through respective check valves with a source of a pressurizing fluid and with said load, a drive side pressurizable in opposite directions to draw said fluid into and discharge said fluid from a respective output side, and a connection between each pressure side and the respective output side whereby each pressure converter has a member displaceable by pressurization of the respective drive side; a respective displacement measuring device cooperating with each of said members for measuring the displacement of each of said members; a common control unit for controlling the pressurization of each of said drive sides so as to reduce an output pressure of a respective output side of one of said pressure converters as the respective member approaches a limiting position in a pressure stroke of said one of said pressure converters, and simultaneously increasing an output pressure of a respective output side of another of said pressure converters and effecting a displacement of the respective member of said other pressure converter by initiating a pressure stroke of said other pressure converters, the pressurization of said drive sides being controlled through respective valves and a common controller for said valves forming said control unit and receiving inputs from respective displacement measuring devices responding to the positions of said members, the pressure strokes being repeated until a certain pressure is reached at said load; and proportional/integral regulator between said output sides and said pipe for delivering a signal to said common controller.