American Efficiency Services

Patience is a Virtue When Searching for Inleakage Failures

2012-01-05T20:39:00.001-05:00

A power plant in Texas with an 830 megawatt turbine / condenser tried various methods and other vendors to identify the source of condenser inleakage that was contributing to >30 scfm of off-gas flow and 3.27” Hg of unit back pressure. All these attempts failed to pinpoint the root cause of the issue, so in October 2011, American Efficiency Services was called upon for help.

Within the first six hours, AES identified the root cause of high off-gas and back pressure as the 6A Low Pressure Heater, Normal Vent Valve Line. The line was deteriorated at a weld that was allowing the air into the steam space.

After temporary repairs were made to the leaking area by placing a combination of duct tape and RTV sealant over the breech, the condenser off-gas decreased from >30 scfm to 8 scfm. There was still leakage recorded through and around the temporary patch during the retests. Permanent repairs to the vent line were scheduled for the upcoming outage. There were still nine additional leaks that were not addressed while the inspection crew was on-site. Condenser off-gas is expected to decrease to <3 scfm after permanent repairs. That is equivalent to 0.36 scfm per 100 megawatts, well below the industry standard of 1 scfm per 100 megawatts. Finally, the customer had an answer and a plan thanks to the AES crew and their findings.

Indeed, during our years of conducting inspections, we’ve learned that you must be patient and not assume a component is operating under a positive pressure. It was determined by plant personal that this area was previously overlooked because it was assumed to be operating under a positive pressure. AES always thoroughly inspects all areas to ensure all leaks are identified during a condenser air inleakage inspection.

Success in a Steel Plant

2011-12-13T17:09:00.001-05:00

AES recently performed a condenser cleaning for a customer in the Midwest.

At the start of the job, the plant had 16 cm HG absolute. Many of the condenser tubes were more than 50% blocked - truly the toughest conditions we've ever seen before a tube cleaning. AES's on-site crew, under the direction of Project Manager Shane Kiel, worked out a plan of attack and finished the job on time and on budget. Our work reduced the plant's numbers to 7 cm HG, with even greater improvement to be seen after the scheduled March cleaning.

The plant manager and site contact are extremely pleased with AES' work, noting that they will share this success story with other steel mills in the area, and will explore the possibility of having AES come on-site every three months to clean.

This is the kind of performance and results that AES strives for on each and every project. We always want to help our customers reach peak performance, and we are proud of our employees hard work, dedication, and initiative! Thanks to Shane, Rob LaRose, Rob Klinger, Eddie Szymanski, Nick Renfert and Tim Renfert.

Inleakage Problems Not Always What They Seem

2011-10-07T18:09:00.000-04:00

American Efficiency Services (AES) dispatched a leak detection crew to a customer’s site located in the Northwest on Tuesday September 27, 2011. The scope of work was to identify the source of condensate contamination of the unit’s condenser hotwell. The condensate sodium levels were recorded at 674 ppb and the cation conductivity was recorded at 56.8 microMhos. One third of the cooling water is pulled from a mine which is 25% sodium; the other two thirds is river water. The sodium levels in the cooling water are extremely high compared to most other cooling water sources, meaning it does not take a large leak to show high levels of contamination.

The unit had two condensers with two tube bundles on each condenser and the cooling water flowing in a serpentine style. The ‘B’ and ‘C’ bundles were drained first and helium inspected with no indication of leakage. The plant was adamant that the source of leakage was contained in the ‘B and ‘C tube bundles, so these tube bundles were drained during the second shift of inspecting with the same negative results for leakage. The next step in the procedure is to inspect the other two tube bundles to confirm that they are or are not the source of leakage. During the inspection of the ‘A’ and ‘D’ tube bundles no leakage was recorded. All waterbox seams and penetrations were also inspected with no indications of leakage.

Test shots (helium applied to an intentionally created leak on the condenser through a drain or vent) were all positive throughout the inspections. Test shots are conducted prior to, during, and after all inspections that provide negative indications of leakage to ensure the sample system is operating properly.

The initial thought process of plant personnel after a situation of this nature is to assume the leak is being closed off due to temperature and/or debris. It is AES’s experience that temperature or debris causing a tube leak to not be identified occurs only in a small percentage of cases, especially when considering the amount of contamination recorded.

The levels of contamination are always recorded throughout the process by our Project Managers to assist in evaluating the probability of leakage in a certain bundle. During all manipulations of removing and returning the tube bundles to service the sodium and cation conductivity levels never decreased. There were fluctuations of the level when tube bundles were being manipulated but nothing of significance. Since there was always contamination of the condensate this suggests that the source of leakage had never been exposed. Since there are very few, or in some cases no other ‘known’ potential sources of contamination of condenser condensate, it is difficult at times to consider that the problem is not a condenser tube leak.

Helium inspections of condenser tube bundles for the identification of tube leaks are very successful and precise. In this instance the helium inspection was very valuable in ruling out the condenser tube bundles as the source of leakage. Once the inspection crew had collected data and was able to adamantly state their findings, “there is not a tube leak on this condenser”, the plant personnel began to listen to other recommendations.

Prior to the tube inspection a unit walk down is conducted to observe current conditions and collect notes. During the walk down for this job it was noted that the condensate pump pit had a standing water level. When asked about the water level the plant response was that there is always some water level in the condensate pump pit. After the tube inspection the water level in the pit was revisited. It was recommended that the water level of the pit be pumped dry so an inspection of the piping could be conducted.

While the pit was being pumped dry another question and answer session was conducted. One question was what other plant operations were being conducted during Saturday evening on September 24 that could have potentially created a leak. The response was that the condensate pumps were being manipulated at about the same time the condensate contamination increased. Manipulating condensate pumps does not generally cause a concern with condensate contamination so it was not originally factored into the thought process. With the new data that the condenser tube bundles were not the source of leakage, the condensate pit was full of contaminated water, and that the contamination became present during the manipulation of the condensate pumps a new primary suspect was identified.

Once the condensate pump pit was drain a helium inspection was conducted on all associated piping, valves, flanges and seals. An immediate, substantial indication was recorded on the #33 Condensate Pump. During the isolation of the source it was identified that the pedestal flange had a small leak on a weld that was currently drawing air into the system but had been drawing contaminated water into the system prior to the pit being drained.

Once the condensate pump pit was drained of the water the condensate contamination levels began to decease. The leak was then temporarily repaired until permanent repairs could be made during the next unit outage.

Although condensate contamination is the primary source of leakage (more than 99% of the time), things are not always what they seem. Helium leak detection was able to quickly eliminate what the suspected source of leakage was and allow personnel involved the ability to confidently redirect their focus to the possibilities that make up that other 1%.

Why Choose Helium Leak Detection?

2011-09-02T12:50:00.000-04:00

Because AES believes that helium leak detection is the most accurate and comprehensive way to find leaks in systems under positive and negative pressure, we have developed a methodology to find all of the leaks within a system. In practice, AES has found that identifying all of the leaks (even the very small ones) in a system gives the plant a “heads up” on spotting the next potential trouble spot.

A complete condenser air inleakage inspection performed yearly on each unit, preferably just prior to a scheduled outage, becomes part of a preventive maintenance program and reduces the number of emergency leak situations experienced by plants.

We've also developed a reporting system for inspection findings that is comprehensive, aids in repairs and provides a record of potential patterns of failure for more extensive maintenance. Our definitive leak tags, clear close up pictures of positioning of leaks, and our knowledge of systems developed over years of inspections in hundreds of plants has made AES the company to call when you want a “complete inspection”.

Why Choose AES?

2011-08-24T21:00:00.001-04:00

We've built our business on the following principles:

Commitment
AES pledges to deliver the most comprehensive leak detection inspection services available. The service will be delivered by knowledgeable, well trained technicians based upon your needs and requirements. We will assist you in correcting problems where permissible and requested. Our goal is to partner with you to improve the performance of your systems and to reduce operating costs.

Integrity
AES's service is built upon our guarantee: we will find your leak(s) or there is no charge for our services. We will employ helium based technology and a systematic inspection methodology to find all leaks registering on our equipment so that when corrected, unit performance will improve.

Quality
We constantly inspect, test and upgrade our equipment. We train our personnel using third party classes, on-the-job instruction, and video based training. We take time to allow crew leaders to develop into a leadership position by exhibiting knowledge of the systems to be inspected using the AES methodology as well as inspection team building. We always send a crew that we feel confident will complete the job to your satisfaction.

Performance
We require our technicians to follow AES methodology and procedures, while adhering to plant policies, delivering a complete inspection of each unit including all valves, welds, penetrations, rupture disks and all other components of the system inspected. The time required for a complete inspection is based upon our experience with similar sized units. We are efficient, taking the necessary time to do a complete inspection. Quite simply we “find more leaks” than our competitors.

Reporting
AES has developed a reporting system designed to help you document maintenance and performance improvement. Leaks are retested, impact on system determined (size), detailed location photographs are taken (more than one if the location requires), details are entered on a tag posted at the leak and all of the information is pulled together in a final comprehensive report. Our reports include all available information on the leak including severity and potential effects on performance, suggestions for repairs and detailed statistics to help determine when additional attention is needed on a particular set of parts within the system such as valve packings.

To choose AES for your condenser inspection and tube cleaning needs, call us at 877-816-9081. We are available for you 24 hours a day, everyday.