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V-1081 — Hydrotreater Feed Drum V-1081

Amine Treating Unit · Hydrotreater Feed service · Installed Aug 29, 1998 (28 yrs in service)

Medium
Current Min. Thickness
1.154 in
t-min 1.067 in
Measured Corrosion Rate
0.87 mpy
ML-predicted: 1.62 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. 2
Joint Efficiency0.85
Design Pressure356 psig
Design Temperature736 °F
Operating Pressure249 psig
Operating Temperature605 °F
Diameter79 in
Nominal Thickness1.201 in
Corrosion Allowance0.0938 in
H2S / Chloride31 / 224 ppm
Flow Velocity12.7 ft/s
Process pH6.62
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
3.08 mpy
Predicted corrosion rate under these conditions (+2.21 mpy vs. current measured rate)
Implied Remaining Life
28.2 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 — High-Temperature Sulfidation

API 571 §4.2.11

Reaction of sulfur compounds with steel at high temperature (>500°F) in the absence of water; rate governed by sulfur content, temperature, alloy content.

Recommended inspection approach: UT thickness per Modified McConomy-curve risk ranking; RT/UT at known high-rate locations identified by process simulation.

Inspection History

UT thickness readings, most recent first

DateMethodCML CountAvg ThicknessMin CML Thickness
Aug 22, 2026UT Spot81.1728 in1.1544 in
Jun 16, 2025UT Grid + RT81.1788 in1.1740 in
Dec 27, 2023UT Spot81.1793 in1.1713 in
Sep 4, 2021UT Grid (API 572)81.1817 in1.1799 in
Jun 6, 2018UT Grid (API 572)81.1846 in1.1756 in
Sep 30, 2016UT Spot81.1849 in1.1786 in
Dec 1, 2014UT Grid (API 572)81.1879 in1.1757 in
Feb 1, 2012UT Grid + RT81.1909 in1.1907 in
Jun 17, 2010UT Grid (API 572)81.1916 in1.1904 in
May 24, 2007UT Spot81.1918 in1.1760 in
Dec 2, 2004UT Grid (API 572)81.1931 in1.1736 in
Apr 6, 2003UT Grid + RT81.1973 in1.1786 in
Sep 22, 2000UT Grid + RT81.1995 in1.1897 in