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V-1338 — Atmospheric Gas Oil Drum V-1338

Sulfur Recovery Unit · Atmospheric Gas Oil service · Installed Aug 29, 1998 (28 yrs in service)

High
Current Min. Thickness
0.926 in
t-min 1.413 in
Measured Corrosion Rate
21.98 mpy
ML-predicted: 19.58 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-240-304L Stainless
Design CodeASME BPVC Section VIII, Div. 2
Joint Efficiency0.85
Design Pressure468 psig
Design Temperature735 °F
Operating Pressure414 psig
Operating Temperature578 °F
Diameter84 in
Nominal Thickness1.561 in
Corrosion Allowance0.1250 in
H2S / Chloride25 / 33 ppm
Flow Velocity4.8 ft/s
Process pH8.46
InsulatedYes

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
14.15 mpy
Predicted corrosion rate under these conditions (-7.83 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 Grid (API 572)80.9464 in0.9264 in
Mar 9, 2025UT Spot80.9780 in0.9755 in
Jan 6, 2023UT Spot81.0270 in1.0234 in
Oct 30, 2020UT Grid (API 572)81.0766 in1.0604 in
May 2, 2018UT Grid (API 572)81.1316 in1.1154 in
Oct 17, 2015UT Grid + RT81.1836 in1.1643 in
Oct 14, 2013UT Grid + RT81.2302 in1.2284 in
Mar 13, 2011UT Grid (API 572)81.2878 in1.2763 in
Dec 24, 2008UT Grid + RT81.3364 in1.3292 in
Jan 22, 2006UT Grid + RT81.3991 in1.3936 in
Sep 5, 2003UT Grid (API 572)81.4509 in1.4416 in
Jul 25, 2000UT Grid + RT81.5231 in1.5136 in