Method for delivering a tool to the interior of a heat exchange tube
View Patent ↗A delivery system for remotely driving an eddy current probe through the tubing of a heat exchanger. The system uses a flexible shaft and air pressure to move an inspection probe through the heat exchanger tubes. The flexible shaft initially drives the probe through a sealed conduit to deliver the probe to the tube end at which point a seal on the shaft near the probe head contacts the tube inner surface allowing a buildup of air pressure behind the seal, thus driving the probe through the tube.
1. A method of delivering a tool through a channel head plenum and into a heat transfer tube of a heat exchanger comprising the steps of:
inserting a delivery conduit into the channel head plenum of the heat exchanger, with one end of the delivery conduit in fluid communication with one end of the heat transfer tube and a second end of the delivery conduit outside of the channel head plenum;
inserting the tool into the second end of the delivery conduit;
inserting a flexible shaft into the second end of the delivery conduit in back of the tool so that the tool is between the flexible shaft and the heat transfer tube;
pushing the flexible shaft and the tool through the delivery conduit and into the heat transfer tube;
slidably sealing the flexible shaft around an inner circumference of an inner wall of the heat transfer tube with a first seal to form a substantially fluid tight seal while enabling the flexible shaft to move within the heat transfer tube;
slidably sealing the flexible shaft to an interior wall of the delivery conduit with a second stationary seal so that an interior of the delivery conduit and the interior of the heat transfer tube between the first seal and the second seal becomes a substantially fluid tight chamber; and
forcing a fluid into the one end of the heat transfer tube to move the tool through a portion of the interior of the heat transfer tube.
2. The method of claim 1 including the step of creating a substantially fluid tight seal with a third seal supported between the delivery conduit and the heat transfer tube with the third seal configured to enable the flexible shaft and tool to slide there through.
3. The method of claim 1 including the step of creating a fluid inlet through the delivery conduit between the second seal and the third seal.
4. The method of claim 3 including the steps of slidably sealing a portion of the flexible shaft between the interior wall of the delivery conduit and the flexible shaft with a fourth seal supported between the second end of the delivery conduit and the second seal to create a ventilation chamber in the interior of the delivery conduit between the second seal and the fourth seal that the flexible shaft can slide through; providing a coupling in the delivery conduit to the ventilation chamber.
5. The method of claim 3 including the step of configuring the second seal so that the flexible shaft and the tool can exit the delivery conduit.