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V-1323 — Wet H2S Gas Vessel V-1323

Delayed Coker · Wet H2S Gas service · Installed Sep 1, 1984 (42 yrs in service)

Medium
Current Min. Thickness
1.513 in
t-min 1.322 in
Measured Corrosion Rate
0.50 mpy
ML-predicted: 1.66 mpy
Remaining Life
60+ 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. 1
Joint Efficiency1.00
Design Pressure390 psig
Design Temperature325 °F
Operating Pressure240 psig
Operating Temperature249 °F
Diameter134 in
Nominal Thickness1.521 in
Corrosion Allowance0.1250 in
H2S / Chloride1385 / 14 ppm
Flow Velocity9.1 ft/s
Process pH4.23
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
0.10 mpy
Predicted corrosion rate under these conditions (-0.40 mpy vs. current measured rate)
Implied Remaining Life
60+ yrs
Implied Reinspection Interval
10.0 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 — Wet H2S Damage (SSC/HIC)

API 571 §4.5.1

Hydrogen-induced cracking (HIC) and sulfide stress cracking (SSC) in carbon/low-alloy steel exposed to wet H2S service. Not detectable by thickness monitoring alone.

Recommended inspection approach: Wet fluorescent magnetic particle (WFMT) and UT shear-wave/AUBT surveys in addition to routine UT thickness, per API RP 571 and NACE SP0296.

This mechanism is crack-dominant — thickness monitoring alone will not detect it. See Standards & Documentation for the full NDE requirement.

Inspection History

UT thickness readings, most recent first

DateMethodCML CountAvg ThicknessMin CML Thickness
Aug 22, 2026UT Spot81.5146 in1.5128 in
May 12, 2025UT Grid (API 572)81.5109 in1.5047 in
Aug 4, 2023UT Spot81.5153 in1.5048 in
Jan 31, 2022UT Grid (API 572)81.5133 in1.5029 in
Dec 17, 2019UT Spot81.5158 in1.5027 in
Apr 8, 2017UT Spot81.5161 in1.5100 in
Apr 9, 2015UT Grid (API 572)81.5141 in1.4957 in
Jun 3, 2013UT Spot81.5144 in1.4989 in
Dec 3, 2010UT Grid + RT81.5159 in1.5117 in
Jun 12, 2008UT Grid + RT81.5155 in1.4987 in
Aug 22, 2005UT Grid (API 572)81.5139 in1.5073 in
Dec 23, 2002UT Spot81.5187 in1.5156 in
Sep 26, 1999UT Spot81.5195 in1.5033 in
Jul 5, 1997UT Grid + RT81.5179 in1.5153 in
Oct 17, 1995UT Grid + RT81.5183 in1.5045 in
Mar 12, 1994UT Spot81.5176 in1.5036 in
Apr 12, 1992UT Grid (API 572)81.5165 in1.5002 in
Jan 12, 1989UT Spot81.5180 in1.5166 in
Mar 23, 1987UT Grid (API 572)81.5186 in1.5137 in