Matt Harrison from Centrica Energy in North Lincolnshire very kindly took the time to share the following case study with us, which describes the site's recent success using the Ultraprobe 2000 to find a troublesome condenser tube leak, that could have cost the company a potential £85,000.

"Brigg Power Station is a 260 MW Combined Cycle Gas Turbine power station, which consists of 4 GE frame 6 Gas Turbines, 4 Heat Recovery Steam Generators (HRSG) and 2 GE Steam Turbine Generator Sets."

"Each steam turbine has a water cooled condenser, which condenses the used steam back into water to be re-used in the HRSGs. The condenser is a 4.8m x 4.5m carbon steel shell, which is connected to the end of the steam turbine via a flexible seal, with a cooling water inlet/outlet and return boxes."

"Inside the condenser are 2 bundles of tubes, each comprising of 2,430 admiralty brass tubes, which are expanded into a tube nest plate in the water box."

"For a couple of months, we had been experiencing a small leak on one of our condensers, which would appear and then disappear. We didn't want to take the plant off-line due to high market prices, loss of availability and the manpower required to locate the leak, so we were carefully managing the leak with increased chemical dosing and boiler blowdown."

"On New Year's Eve, we finally had an opportunity to take the condenser off-line and investigate the leak further."

"In the past, if we had found a cooling water leak, we would isolate the cooling water side, enter the water box, put the steam space under vacuum and apply shaving foam to the tube nest. This foam would be sucked into the leaking tube, and we would then plug both ends."

"This method is very time-consuming (10 to 12 hours) in terms of manpower, preparation of plant conditions, etc, and wasn't very effective in locating small leaks, which could be picked up by the on-line chemistry equipment. This is why we decided to approach the leak detection using the Ultraprobe 2000."

"We went into the steam space and found a small water leak, which subsequently pointed us into the general area of the leak. We then de-isolated this space, drew a vacuum and entered the water box side to gain access to the tube nest and plate. Using the Ultraprobe on a fixed-band frequency, I performed a quick scan and found a big leak in less than 2 minutes."

"I narrowed down the area of the scan by using the rubber focusing probe, so as to identify the offending tube. This tube and 2 tubes in the adjacent area were then plugged - a scan was carried out and nothing was detected."

I then made one final scan and found a further 2 leaks - in the end, we plugged 9 tubes, scanned again and no additional leaks were found. The condenser was then de-isolated and the plant was declared available again some 5 hours earlier than expected."