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V-1304 — Hot Hydrocarbon Vapor Drum V-1304

Alkylation Unit · Hot Hydrocarbon Vapor service · Installed Aug 27, 2004 (22 yrs in service)

High
Current Min. Thickness
0.660 in
t-min 0.798 in
Measured Corrosion Rate
12.07 mpy
ML-predicted: 8.39 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 Efficiency0.85
Design Pressure540 psig
Design Temperature331 °F
Operating Pressure315 psig
Operating Temperature216 °F
Diameter41 in
Nominal Thickness0.939 in
Corrosion Allowance0.0938 in
H2S / Chloride18 / 184 ppm
Flow Velocity2.9 ft/s
Process pH8.85
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
6.10 mpy
Predicted corrosion rate under these conditions (-5.97 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 — Corrosion Under Insulation (CUI)

API 571 §4.3.5

Localized external corrosion beneath insulation where moisture is trapped, most severe in the 140–250°F operating band.

Recommended inspection approach: Insulation removal at high-risk locations (nozzles, low points), profile radiography, or guided-wave UT screening per API 570/RP 583.

Inspection History

UT thickness readings, most recent first

DateMethodCML CountAvg ThicknessMin CML Thickness
Aug 22, 2026UT Grid + RT60.6759 in0.6596 in
Apr 4, 2024UT Grid + RT60.7013 in0.6877 in
Aug 13, 2021UT Spot60.7327 in0.7269 in
Aug 10, 2019UT Grid + RT60.7618 in0.7593 in
Sep 27, 2017UT Spot60.7821 in0.7777 in
Mar 7, 2015UT Grid (API 572)60.8120 in0.7923 in
Feb 25, 2013UT Grid + RT60.8340 in0.8247 in
Aug 8, 2011UT Grid (API 572)60.8566 in0.8378 in
Jun 19, 2009UT Grid (API 572)60.8843 in0.8839 in
Feb 11, 2007UT Grid (API 572)60.9099 in0.9020 in