Power Plant Cooling Water Intake Inspection

Discussion of Commercial Diving topics (such as pipeline inspection).

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Power Plant Cooling Water Intake Inspection

Postby rovsteve » Mon Mar 14, 2005 4:53 pm

Last week (3/9/05) I was asked to do a demonstration inspection with my VideoRay ROV of the cooling water intake system for an Oil Fired Electrical Power Generation Station in St. Petersburg, Florida.

The power plant uses saltwater drawn from Tampa Bay to cool the boiler units. The water is pumped into the plant via 52 inch diameter pipes. Once inside the water is distributed from a large 10 ft by 20 ft metal structure called the waterbox.

To inspect the intake pipes, the pumps were shut down and the waterbox drained. Workers entered the waterbox and lowered the VideoRay down into the sump where the 52 inch pipe enters the waterbox.

I slowly flew the ROV about 230 feet, into the 300 ft. pipe, while stopping to observe specific areas requested by the plant engineer. I recorded the video on mini DV tape for the engineer and his crew to review later. The major concern is with the buildup of barnacles.

Normally, a five person dive team takes about 1.5 days to conduct this type of inspection; my total time from setup to teardown was about 35 minutes. During the period of inspection these units, one of six, are shut down and not able to produce power. The downtime cost plus the cost of the dive team makes this type of inspection very costly. The plant engineer was very happy with the minimal downtime and the high quality video to review later, He was impressed with the ability to direct, in realtime, the inspection process.

After the internal pipe inspection I was requested to inspect a series of concrete posts that form a barrier at the exit of the cooling water discharge canal. The current flow was about 2 knots, due the outflow from the plant and the ebb tide. To position the VideoRay for to inspect these posts I taped 10 pounds of dive weights to the tether, about 15 feet behind the ROV. The tether handler, standing on the walkway over the posts, lowered the ROV to the waterline and then tossed the weighted tether upstream. The weights anchored the ROV in position just ahead of the posts and enabled me to fly from side to side and inspect three posts at a time. To move to the next position the tether was retrieved and the above procedure repeated.

Inspecting the power plant was a very interesting challenge and a new experience for me. However, the techniques used were the same as for other tasks with the VideoRay, which reinforces the concept of practicing basic ROV skills and adapting these techniques to new projects.

The attached photos show the plant and discharge canal, the waterbox and inside the pipe. some of the images are video frame grabs, others were taken with digital still camera.

Steve Van Meter
Cocoa, Florida

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