Description
Challenge
Effective foreign object search and retrieval (FOSAR) and FOD removal are critical to the power generation industry. FOD presents mechanical and safety risks in and around power plant equipment and most often requires complete plant shutdowns to remove them. Emergency shutdowns are never cost-effective or desirable scenarios, so many groups will practice FOD removal during scheduled shutdowns in preparation for such events.
One such customer will simulate the FOD removal of a spanner wrench lodged inside a vertical pipeline. Removing this type of FOD requires a retrieval solution with considerable tensile strength to dislodge, grasp, and maneuver the spanner wrench back up the pipe’s bends. The solution needed to be strong, reliable, and easy to use. The spanner wrench is 400 grams in weight, non-ferrous, and has a 10 mm loop on its end.
The customer can not use a magnet or suction-powered retrieval tool for this particular FOD: the wrench is not magnetic, and suction is unreliable.
Development
With substantial FOSAR/FOD removal experience and tool engineering, InterTest designed a solution consisting of a 50-meter steel spring-coated wire with a 5 mm ball bearing on its end and a 25-meter snare retrieval tool. The design allows an operator to snake the 50 m ball bearing wire down to the FOD location, pass it through its 10 mm loop, and then cinch the 25-meter snare around the ball bearing and pull the wrench out.
Solution
During the planned shutdown, operators will extract the wrench from a thin pipe with multiple bends roughly 20 meters from the opening. A ball bearing on a 50-meter wire will be passed through the 10 mm opening in the spanner wrench, and then the snare will be used to grab the ball bearing and pull the wire back to the surface. With the wire through the spanner wrench, the operator will pull to dislodge and remove it confidently.
InterTest based the snare tool design on the 50-foot iGrab 4mm Snare Manual Retrieval Tool standard product. The throw handle was re-engineered to accommodate the slack in the wire that accompanied the extra length requirement. The ball bearing wire was specifically engineered with steel spring coating to have enough tensile strength and resilience to be pushed around pipe bends and successfully fed through the 10 mm loop on the wrench.
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