SUMMARY - Solex Robotics demonstrated Maverick for first time deployment through a floating roof. Maverick and it supporting systems met the safety permitting requirements set by the Mobil's Health and Safety Department for operations in a tank containing diesel fuel.
MOBIL TEAMWEST TORRANCE, CALIFORNIA
On March 20th Maverick was demonstrated in a diesel storage tank at the Mobil refinery in Torrance, California to Mobil and Shell Oil, refinery directors from Spain and Hungary, and to DOE personnel. Maverick was first demonstrated a few months prior on November 13th in a water-filled tank to the petroleum industry at the Mobil Oil refinery in Paulsboro, New Jersey. The robot has undergone extensive modification to upgrade all of the safety systems and to correct deficiencies noted in the previous set of tests.
The goals of this demonstration were to test the equipment modifications and pursue safety approvals for use in product tanks. Solex Robotics is now on the Approved Contractors List allowing access to the Torrance Mobil refinery and all personnel hold badges and clearances into the refinery for the next year of operations. An extensive safety review was conducted and procedures to allow safe deployment of the equipment into a diesel tank were jointly written to control operations, along with all of the required permitting.
The most major upgrade to the equipment was complete redesign of the purge and pressurization system for the robot and umbilical. The cabling was extended to simplify operations. Only half of its length was needed for this 120-foot diameter tank. The rugged pressurized umbilical was more than sufficient in length, and would have allowed inspection of adjacent tanks without having to move the control trailer, which will greatly simplify setup and deployment in future tank inspections. The purge and pressurization controls operated as designed and provided continuous safe operation of the robot during the week of testing with only minor system leaks which were quickly corrected.
The second major modification to the equipment was alteration of the inspection probe array. Previously, the ultrasonic (UT) inspection probes were exposed to the product and were mounted on the bottom front of the robot housing. The UT probe faces posed a safety problem since they were vulnerable outside of the housing to being struck by obstructions inside the tank as proven in the first demonstration. The UT transducers are now enclosed in the shell casing.
The demonstration tank had been in continuous operation for 19 years without a floor inspection. The tank bottom was coated with a layer of sludge, consisting of a stringy black jelly mixed with sandy grit. As in the last test, the sludge totally obscured the cameras as the vehicle moved through the fluid, and the diesel was less transparent than the water in the previous tank. The brush mounted on the front of the vehicle was not sufficient to clear away enough sludge to get consistent UT readings. A squeegee was added in front of the brush to improve sludge removal on the second day in the tank. It worked well and greatly improved the ability to read the thickness of the tank bottom. The new UT system including the delays and a new type of transducer worked well in scanning the steel plates of the tank bottom. A deficiency was noted with the new multiplexor and it was replaced with the backup spare. The attendees of the demonstration were very impressed with the capabilities of the inspection system analysis software.
The sonar-based tracking system was the last subsystem operational within the tank. The beacons were modified to work from the outside of the tank, and the system was altered to provide better accuracy. Extensive testing was conducted on the tank acoustics and a problem was found in transmission of sound from the beacons through the tank wall and into the diesel. The sound was not reaching the robot by a direct path, but was echoing several times before reaching the robot. Despite the extensive corrective efforts, consistent positioning operation could not be obtained. The inability to track the robot's position within the tank restricted the ability to scan the tank floor to areas near the entry point. Had the system been working properly, a complete inspection of the tank floor could have been performed capping the success of the demonstration.
All of the equipment with the exception of the tracking system was operating properly on the day of the demonstration. Throughout the week, all of the problems that had cropped up were dealt with on site. This provided Mobil personnel with a demonstration of Solex's in-service professional capabilities. Overall, the attendees were very impressed with Maverick and its capabilities. Shell Oil personnel commented that robotic tank inspection would indeed be a reality within a short couple of months, which was markedly different from their views prior to the demonstration.
The demonstration was a great success overall. More industry personnel are now aware and supportive of this type of service and are awaiting its availability, as are the operators overseas. There is an immediate market for internal tank inspection and Solex is actively pursuing correction of the deficiencies identified by the testing and should begin commercial tank inspections shortly as a result of contacts made during the demonstrations.