While reviewing Valve Body drawing 16B2201, it was discovered that an area in the packing
bore has the possibility to not meet the minimum wall requirements of
ASME B16.34 for a Class 150 valve at the minimum material condition due to a potential stack up of tolerances.
Upon discovery of this possible failure to comply, an investigation was performed on all NPS 3-12 Type A11 Class 150 Seismic Plate Valve Bodies and it was determined that this issue was isolated to the NPS 8 Type A11 Class 150 Seismic Plate Valve Body per drawing 16B2201.
It is the opinion of Fisher that there is no inherent safety risk associated with this situation. Fisher will be working with the individual plants [Clinton Power Station and Watts Bar] in question to measure the actual dimensions of the bodies to determine if a problem exists and will take appropriate corrective action.
Fisher Information Notice:
FIN 2012-01