Corrosion rate & remaining life
Two thickness readings turned into a short-term and a long-term rate, a remaining life and the next inspection date API 510 and 570 would set.
Facilities & integrity
Bearing defect frequencies
BPFO, BPFI, BSF and FTF from bearing geometry and shaft speed, with the harmonics and the minimum spectrum Fmax you need to see them.
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How it is calculated
- BPFO = (n/2)(1 − (d/D)·cosφ)·f, BPFI = (n/2)(1 + (d/D)·cosφ)·f.
- BSF = (D/2d)(1 − ((d/D)·cosφ)²)·f and FTF = ½(1 − (d/D)·cosφ)·f, with f the shaft frequency.
- Frequencies are reported in Hz, CPM and orders of running speed, because the three conventions all appear on the same plant.
- Fmax is suggested as 3.5 × BPFI, the usual minimum for capturing the diagnostic harmonics.
Standards it speaks
Where this stops being true
The equations assume pure rolling contact with no slip, and real bearings slip by one to two per cent under load — so a spectral peak a couple of per cent off a calculated frequency is a match, not a miss. The catalogue geometry here is generic: two bearings with the same bore number from different manufacturers can have different ball counts, and a wrong ball count moves BPFO by a whole order. Where the fault frequency matters, get the geometry from the manufacturer.
The capability that automates this
- FA-01Rotating Equipment Condition MonitoringListens to pumps, compressors and turbines continuously and identifies the specific defect — bearing, imbalance, misalignment, looseness — from the vibration signature.
- FA-02ISO 14224 Predictive MaintenancePuts every piece of equipment into one reliability taxonomy so that failure rates mean the same thing across all fields, and maintenance is planned from them.
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