Abstract
In July of year 2020, The Electric Power Research Institute (EPRI) Condition Based Maintenance User Group (CBMUG) held an annual meeting. During the proceedings, the group requested that an effort be made to pursue changes to ASME OM ISTB. Two changes were requested:
1. Changes to ISTB-3510 concerning calibration of vibration instruments at low frequencies.
2. Changes to various locations wording concerning the use of the term “broadband (unfiltered)” vibration data.
In July of 2020, EPRI submitted proposed changes to the ASME ISTB Code Committee and presented the requests during a virtual meeting.
Change 1: Operating Nuclear Plants are required by NUREG-1482 to follow ASME OM ISTB-3510(e) calibration requirements for vibration instruments used for in-service testing. Instruments accuracy must be ± 5% from 1/3 running speed to at least 1000 Hz. The industry has historically experienced difficulty in meeting this requirement on slow speed pumps resulting in proliferation of relief requests in the late 1980’s and early 1990’s. Revision of NUREG-1482 in 2013 caused concerns among users in relation to the validity of the existing reliefs.
Change 2: The term “Broadband Unfiltered” is used in various locations in the OM code to describe vibration data. This terminology was common in an earlier era of analog vibration data collection equipment but is confusing to a new generation of vibration analysts accustomed to using modern digital vibration instruments.
