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V-1099 — Wet H2S Gas Drum V-1099

Amine Treating Unit · Wet H2S Gas service · Installed Aug 31, 1990 (36 yrs in service)

Critical
Current Min. Thickness
0.803 in
t-min 0.829 in
Measured Corrosion Rate
4.73 mpy
ML-predicted: 4.96 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-240-316L Stainless
Design CodeASME BPVC Section VIII, Div. 1
Joint Efficiency1.00
Design Pressure565 psig
Design Temperature538 °F
Operating Pressure455 psig
Operating Temperature395 °F
Diameter48 in
Nominal Thickness0.978 in
Corrosion Allowance0.0938 in
H2S / Chloride1102 / 262 ppm
Flow Velocity3.0 ft/s
Process pH8.33
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
6.16 mpy
Predicted corrosion rate under these conditions (+1.43 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 — 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 Spot40.8063 in0.8034 in
Jan 18, 2026UT Grid + RT40.8117 in0.8031 in
Dec 13, 2023UT Grid + RT40.8206 in0.8137 in
Apr 1, 2022UT Spot40.8275 in0.8151 in
Jan 13, 2019UT Grid + RT40.8454 in0.8357 in
Mar 29, 2017UT Grid + RT40.8523 in0.8366 in
Apr 29, 2015UT Grid + RT40.8640 in0.8599 in
Mar 2, 2012UT Grid (API 572)40.8785 in0.8666 in
Sep 20, 2010UT Spot40.8811 in0.8748 in
Dec 25, 2007UT Grid + RT40.8963 in0.8943 in
Apr 2, 2006UT Spot40.9065 in0.8995 in
Oct 12, 2004UT Spot40.9114 in0.8960 in
Jan 28, 2003UT Spot40.9189 in0.9177 in
Aug 7, 2000UT Grid + RT40.9300 in0.9118 in
Oct 27, 1997UT Grid + RT40.9435 in0.9329 in
May 26, 1995UT Spot40.9617 in0.9432 in
Dec 1, 1993UT Grid (API 572)40.9594 in0.9464 in