This invention relates to a method and apparatus for controlling the installation of mechanical tube plugs. More particularly, this invention relates to a controller system for installing mechanical tube plugs including recording, monitoring, and controlling the torque applied in the process to evaluate the work done to assure the integrity of the plug installation. Still more particularly, this invention relates to a method and apparatus for controlling mechanical tube plugging through a remotely-located control console cooperating with a proximately-located solenoid box for controlling tool operation, and sensing, monitoring, and controlling torque during working. More particularly, this invention relates a method and apparatus for controlling tooling for remote installation of mechanical plug tubes for controlling a rotation station for brushing, sizing, plug rolling, and a plug cartridge insertion for placing the plug into a tube sheet.
A rotation station for remotely installing mechanical tube plugs is shown and described in detail in pending U.S. application Ser. No. 853,587, to issue on Feb. 2, 1988 as U.S. Pat. No. 4,722,122 (PCT Publication No. WO87/06333 published on Oct. 22, 1987). As is well-known, a heat exchanger in a nuclear steam supply system extracts heat from a closed primary loop fluid that circulates through the reactor and the heat exchanger and transfers the heat to a closed secondary loop fluid that circulates through the heat exchanger and a steam turbine where energy is extracted in the form of mechanical energy. Such heat exchangers usually include a vessel having a plurality of U-shaped shaped tubes around which the fluid of the secondary loop passes and through which the fluid of the primary loop circulates. The heated water passes into and through the U-shaped tubes with both ends terminating in a tube sheet so that the fluids are in a heat exchange relationship while passing through the U-shaped tubes. In such systems, it is imperative to maintain the fluids of the two loops isolated one from another. As some of the tubes of the heat exchanger deteriorate, those tubes are removed from service and the heat exchanger placed back into operation.
A method and apparatus for removing a heat exchanger tube is described in the aforementioned publication. By plugging both ends of the tube where the tube terminates at the tube sheet, the deteriorated tube may be removed from service. Thus, a known method for providing a tube includes equipment for and the steps of inserting a mechanical plug having an outside diameter slightly less than the inside diameter of the tube being plugged and inserting the tube plug flush with the tube sheet. Thereafter, the plug is expanded by rolling the inner surface of the plug forming a mechanical roll-joint between the outer surface of the tube plug and the inside surface of the tube. Thus, the steps of brushing, insertion, and rolling in such a heat exchanger are well-known in this art.
As further described in that publication, the rolling equipment, whether manual or automatic, is typically designed to stall at a predetermined torque so that the integrity of the mechanical roll-joint can be inferred from the torque at which the rolling equipment stalled. The rolling equipment is calibrated periodically to insure a consistent and acceptable roll-joint. As further described in the aforementioned publication, the rotational torque applied during each step of the tube installation process is recorded and monitored in real time to assure that the torque applied during each step of installing a mechanical tube plug provides its contribution to the integrity of the installation of a mechanical tube plug. The recorded torque curves further provide documentation for verification of the integrity of the installation or for regulatory purposes.
It is an aim of this invention to improve control of that type of rolling equipment and to control the method of plugging described. Thus, a method and an apparatus for remotely controlling the installation of mechanical tube plugs in which the actual torque applied in the installation process is monitored and controlled is needed to assure the integrity of the plug system. Such a system and apparatus would permit real-time monitoring of the torque applied in each step of the tube installation process, as is desirable, but from a location remote from the site of the tube plug. By featuring all manual control components and monitoring functions at a control panel remote from the tube plugger and connected only by a control cable to a solenoid box proximately-located at the site of operation, an operator may remotely control all of the operations of the equipment, while at the same time monitor those operations, if desired, by television, hard copy or storage monitoring. Such a system includes a strip-chart recorder for recording the torque observed at each state of operation, and means for making a hard copy recording of the torque curves generated during the process. A feature of the control panel would be to provide an auxiliary current loop output which could be used for interfacing with a computer to digitally record the torque signals for purposes of on-screen display, magnetic storage, and subsequent data analysis if necessary.
Thus, it is an overall objection to this invention to provide a method and apparatus for controlling the steps of installing mechanical tube plugs from a remote location.
It is an additional object of this invention to provide a remotely-positioned control console for controlling the operations of plug removal, brushing, plug insertion, and plug rolling during a mechanical tube plugging installation by a remotely-located control panel connected to a proximately-located solenoid box for controlling each of those operations.
It is an additional object of this invention for the control system of the type described to provide a feedback sensing system for torque monitoring and having a torque limit for plug rolling and for safety during the plugging steps.
It is an additional object of this invention to provide a control system which senses and monitors torque during mechanical tube plugging wherein a torque limit system can be overridden.
It is an additional object of this invention to provide a control console for manually controlling plug insertion, drive, and removal operations in a mechanical tube plugging system of the type described.
These and additional objects of the invention will become apparent from the written description of the invention, taken in conjunction with the accompanying drawings.