Effective Age
Expected useful life minus remaining useful life: an age based on condition rather than the calendar, and the figure the reserve table's column should carry.
By Nicolas Reimer, Founder, Baseline PCR · E2018-24 s3.2 · Published September 18, 2026
Effective age is defined in E2018 as the difference between expected useful life and remaining useful life. It is not the calendar age. A well-maintained unit installed in 2004 with a fifteen-year expected life and an observer's remaining-life opinion of eight years has an effective age of seven; a neglected unit of the same vintage might have an effective age beyond its expected life. The point of the column is to show the reader how the condition judgment moved the component relative to the table value.
The most common reserve-table error is printing calendar age in the effective-age column. If the field observer made no RUL opinion and remaining life was computed as expected life minus documented age, then effective age equals calendar age, and the table should say that the RUL was arithmetic rather than judgment.
Related: expected useful life, remaining useful life.
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ASTM E2018-24 is copyrighted by ASTM International and is paraphrased here, never reproduced; buy the guide from ASTM to read the text. This page is general information for practitioners, not engineering, legal or lending advice.