Wednesday, May 23, 2012

TUBE LEAKS: The Art of Accurately and Efficiently Identifying Them

Condenser tube inspections are conducted with the unit on-line. When an operating unit experiences contamination of the hotwell condensate due to cooling water intrusion from a condenser tube failure, it is imperative the source of leakage be identified immediately. All cooling water contains a much greater concentration of dissolved materials than boiler condensate, so even small leaks can cause gross contamination of a steam generating system.

American Efficiency Services technique and experience can identify most failures within one operating shift of gaining access to the suspected waterbox. This includes the identification, plugging, and retesting of the tube bundle.

During a recent condenser tube inspection at a Midwest US customer’s facility, their unit was operating with hotwell condensate contamination levels of 3.80 ppb sodium and 0.15 microMhos cation conductivity. Once safe access to the tube bundle was achievable, it took only 4.5 hours to locate five (5) sources of leakage.

Although in greater than 90% of all condenser tube inspections a tube failure is identified, in this situation all five sources of leakage were contributed to loose plugs. All the plugs were reseated and then retested with no further indications of leakage. Once the tube bundle was returned to service the hotwell sodium and cation conductivity levels remained within plant specifications.

Identifying condenser tube leaks utilizing helium as a tracer gas, coupled with inspection experience, has proven to be the most cost effective method to date of ensuring peak condenser performance. AES has seen several situations where numerous tubes were plugged in a specific area in a desperate attempt to return the unit to service “leak free”. But plugging additional tubes reduces the efficiency of the condenser prematurely. Even though the condenser is designed to withstand a certain percentage of plugged tubes, the life expectancy of the condenser will be reduced over time.

In contrast, using helium as a tracer gas is precise and quick so only the tube(s) leaking are plugged and the condenser is back doing its job, operating efficiently and making the utility money.

For more detailed information on our services and methodology please visit our website at www.AmericanEfficiency.com or call 877-816-9081.

With AES’ guarantee that we will find the leak, you have nothing to lose and everything to gain.

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