Analysis of a 16-inch globe valve with eroded walls
During the course of inspection activities at a commercial nuclear power plant varying degrees of wall tinning were observed in several 16-inch globe valves. The wall thinning was observed at several locations on the bridge and bonnet areas of the valves and was thought to be the result of erosion of the wall material. these valves were routinely subjected to leak rate tests as part of the normal inspection and maintenance activities. Erosion of the valve plug seat sufficient to allow leakage would normally be detected by the leak rate testing. However, the question was raised whether severe erosion in the bridge structure would create the potential for a structural failure that would prevent normal closing and seating of the valve. An analytical assessment or ``scoping analysis`` of one of the valves was undertaken to assess the potential for stresses exceeding yield and to indicate whether a more extensive analysis of the valve would be desirable. a linear-elastic finite element model including the valve body, bonnet region, seat ring, and inlet and outlet bridge structures was developed. The model was subjected to a combination of internal pressure, valve plug seat force, and piping end moments. The results of the analysis indicate that even with erosion more severe than that observed in the actual valves, stress values did not approach yield. From these results it was concluded that yielding of the valve would not be anticipated with the observed erosion levels and that operability of the valves would not be impaired.
- Research Organization:
- EG and G Idaho, Inc., Idaho Falls, ID (United States)
- Sponsoring Organization:
- Nuclear Regulatory Commission, Washington, DC (United States)
- DOE Contract Number:
- AC07-76ID01570
- OSTI ID:
- 10167011
- Report Number(s):
- EGG-M-91653; CONF-920631-45; ON: DE92018034
- Resource Relation:
- Conference: American Society of Mechanical Engineers (ASME) pressure vessels and piping conference,New Orleans, LA (United States),21-25 Jun 1992; Other Information: PBD: [1992]
- Country of Publication:
- United States
- Language:
- English
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