Nuclear, O&M

Environmental protection via valve monitoring

Issue 7 and Volume 99.


Environmental protection via valve monitoring

R.C. Rittenhouse, Managing Editor

Getting to know SSPC

Small fluid leaks (i.gif., liquid, gas or two-phase mixtures) conceivably can go unnoticed in a power plant and, eventually, some effluent might find its way into the environment. Any resulting violation of pollution control rules or other regulations could be costly.

Other expenses from extra maintenance or unscheduled outages also can be high when such leaks occur in valves, pipes or pumps. Hence, the importance of leak detection goes beyond the valve testing and condition monitoring reports that appear in Power Engineering`s special valve feature section beginning on page 21.

The variety of valves now used in power plants presents a challenge to monitor and maintain adequately. Predominant among these are check valves, air-operated valves, and motor- and solenoid-operated valves. As systems become more complex, so does the demand for more versatile monitoring systems.

During the Valve Manufacturers Association of America`s (VMA) November 1994 technical program, M. K. Au-Yang of B&W Nuclear Technologies discussed one example of a non-intrusive valve diagnostic instrument (B&W`s UltraCheck system) that can monitor most valves. This capability includes in situ testing for detection of internal leaks in all power plant components. The system detects leaks and memorizes associated noise levels on a computer monitor and in hard copies.

Check valve testing

As an example, swing and tilting-disk types of check valves, which range in size from 2 to 30 inches, were the subject of recent leak tests. Studies by the Electric Power Research Institute, Institute for Nuclear Power Operations and U.S. Nuclear Regulatory Commission found that many such valves might not be functioning properly.

Au-Yang reported on tests that were administered by the Nuclear Industry Check Valve Group to evaluate various technologies in non-intrusive monitoring of check valves. Acoustic sensors used for leak detection in this system are placed on the high pressure side of a valve to record background noise and on the low pressure side at the suspected leak area.

By comparing signatures from these two sensors, an experienced engineer or technician can detect leaks before they jeopardize plant operations. In one test program with this system, 10 percent of 400 valves were found to leak. The value of avoiding valve disassembly is manyfold. For example, this time-consuming work often is done under hostile conditions in nuclear power plants. Furthermore, most valves disassembled during the studies were in good working order and there is no guarantee that a valve that passes visual inspection will work properly after reassembly.

In short, a state-of-the-art monitoring system seems well worth the initial investment when all of the consequences are taken into account, particularly when pollution control may be a factor.

Organizations worth knowing

Under the heading “organizations worth knowing” comes the Council of Facility Owners (CFO). Created by the Steel Structures Painting Council (SSPC), the owners` council is designed particularly to serve facility owners facing the demands of many regulatory agencies to comply with many environmental and safety regulations.

A two-tiered level of membership serves different needs. The top level `sustaining` membership provides unlimited individual memberships for company personnel and a variety of discounts for publications, training courses and conference registrations. `Patron` member benefits offer several individual memberships plus discounts on training courses and more. One of the most productive activities open to members takes place during the big annual conference. SSPC`s 1995 International Conference & Exhibition set for November 10-16, 1995, in Dallas, will, again, feature CFO peer forums. Five forums were ready at this writing and will get under way on the afternoon of November 13.

Facility owners in each of various categories (e.g., pulp and paper, power industry) will meet together, without vendors present, to air their problems with experts and exchange information. For more information on CFO membership and the peer forums program, contact Terry Sowers, Manager of Member Services, Steel Structures Painting Council, 4516 Henry Street, Pittsburgh, Pa. 16213-2683, or call (412) 687-1113.

Another service of SSPC worth getting to know is the Center for Protective Coatings (CPC). Research under the CPC banner includes studies of environmentally compliant surface preparation. Environmentally friendly surface preparation methods research involves reducing waste from lead paint removal, reducing dust emissions from abrasive blasting, and the impact of environmentally compliant surface preparation on coating performance.

Other work involves the selection, use and performance of coating materials and application methods that can meet environmental requirements. Overall, the CPC seeks better short term testing methods and improved methods for evaluating coating performance, studies coatings performance on all substrates including concrete, and undertakes standards-oriented research to support SSPC standards. Sponsors have ranged from Pennsylvania Power & Light and Buckman Laboratories to the Corps of Engineers. More information on the CPC is available from SSPC in Pittsburgh. END

Paul R. Puckorius, Puckorius & Associates Inc. president, was awarded the annual merit award for 1994. He received the award from the Engineers Society of Western Pennsylvania during its annual International Water Conference. The prestigious recognition is for his 35 years of continuing contributions to the water using industries, including power generation, and for his continued service to the annual water conference. Belated congratulations!