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V-1251 — Crude Oil Drum V-1251

Alkylation Unit · Crude Oil service · Installed Aug 29, 1998 (28 yrs in service)

Critical
Current Min. Thickness
0.744 in
t-min 1.135 in
Measured Corrosion Rate
17.00 mpy
ML-predicted: 18.58 mpy
Remaining Life
0.0 yrs
Next Inspection Due
Feb 20, 2027
Interval: 0.5 yrs (API 510)

UT Thickness Trend

Minimum CML reading per inspection vs. ASME Sec. VIII t-min

Vessel Specification

MaterialSA-240 Duplex 2205
Design CodeASME BPVC Section VIII, Div. 1
Joint Efficiency1.00
Design Pressure642 psig
Design Temperature286 °F
Operating Pressure357 psig
Operating Temperature270 °F
Diameter87 in
Nominal Thickness1.239 in
Corrosion Allowance0.0625 in
H2S / Chloride21 / 33 ppm
Flow Velocity3.5 ft/s
Process pH7.14
InsulatedNo

Corrosion & Remaining-Life What-If

Adjust operating conditions to see the live model-predicted corrosion rate and implied remaining life

Live Prediction — What-If Model
15.69 mpy
Predicted corrosion rate under these conditions (-1.31 mpy vs. current measured rate)
Implied Remaining Life
0.0 yrs
Implied Reinspection Interval
0.5 yrs

What-if model: standardized Ridge regression, R² 0.56 on held-out fleet data (3.25 mpy MAE). Runs entirely client-side for instant feedback — see Model Insights for the full fleet-scale ensemble model used for official predictions.

Governing Damage Mechanism — Naphthenic Acid Corrosion

API 571 §4.2.10

Aggressive, velocity-assisted corrosion in high-TAN crude fractions, most severe 450–750°F; low-alloy/carbon steel is far more susceptible than Mo-bearing or 316 SS.

Recommended inspection approach: UT thickness at high-velocity/turbulent locations; feed TAN monitoring; consider alloy upgrade per API 571 guidance.

Inspection History

UT thickness readings, most recent first

DateMethodCML CountAvg ThicknessMin CML Thickness
Aug 22, 2026UT Spot60.7608 in0.7436 in
Aug 26, 2025UT Grid + RT60.7811 in0.7759 in
Jun 11, 2023UT Grid (API 572)60.8191 in0.8098 in
Apr 5, 2020UT Grid + RT60.8711 in0.8529 in
May 17, 2017UT Grid (API 572)60.9243 in0.9105 in
Jun 15, 2015UT Grid (API 572)60.9552 in0.9380 in
Jun 17, 2012UT Spot61.0058 in1.0008 in
May 26, 2009UT Spot61.0590 in1.0521 in
Jul 1, 2006UT Grid + RT61.1060 in1.1011 in
Dec 23, 2003UT Grid (API 572)61.1473 in1.1340 in
Dec 7, 2001UT Grid (API 572)61.1848 in1.1750 in