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V-1146 — Crude Oil Column V-1146

Crude Distillation Unit · Crude Oil service · Installed Aug 28, 2003 (23 yrs in service)

Medium
Current Min. Thickness
0.287 in
t-min 0.216 in
Measured Corrosion Rate
1.65 mpy
ML-predicted: 1.14 mpy
Remaining Life
43.1 yrs
Next Inspection Due
Aug 19, 2036
Interval: 10.0 yrs (API 510)

UT Thickness Trend

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

Vessel Specification

MaterialSA-516-70 Carbon Steel
Design CodeASME BPVC Section VIII, Div. 2
Joint Efficiency1.00
Design Pressure59 psig
Design Temperature731 °F
Operating Pressure37 psig
Operating Temperature488 °F
Diameter116 in
Nominal Thickness0.333 in
Corrosion Allowance0.0625 in
H2S / Chloride17 / 274 ppm
Flow Velocity13.4 ft/s
Process pH7.17
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
8.14 mpy
Predicted corrosion rate under these conditions (+6.49 mpy vs. current measured rate)
Implied Remaining Life
8.7 yrs
Implied Reinspection Interval
4.4 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 Grid (API 572)80.2918 in0.2875 in
Sep 28, 2025UT Grid + RT80.2989 in0.2832 in
Jun 12, 2023UT Spot80.3004 in0.2819 in
May 13, 2021UT Grid + RT80.3037 in0.2921 in
Jul 3, 2019UT Grid (API 572)80.3071 in0.2971 in
Aug 14, 2017UT Grid (API 572)80.3090 in0.3063 in
May 19, 2015UT Spot80.3113 in0.3001 in
Aug 27, 2013UT Grid + RT80.3164 in0.2992 in
Aug 18, 2011UT Spot80.3159 in0.3046 in
Feb 25, 2009UT Grid (API 572)80.3268 in0.3199 in
Oct 7, 2007UT Grid + RT80.3246 in0.3217 in
Feb 1, 2005UT Spot80.3302 in0.3183 in