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V-1216 — Caustic Wash Vessel V-1216

Crude Distillation Unit · Caustic Wash service · Installed Aug 29, 1999 (27 yrs in service)

Low-Medium
Current Min. Thickness
0.887 in
t-min 0.727 in
Measured Corrosion Rate
1.28 mpy
ML-predicted: 1.21 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-240-316L Stainless
Design CodeASME BPVC Section VIII, Div. 1
Joint Efficiency0.85
Design Pressure175 psig
Design Temperature129 °F
Operating Pressure98 psig
Operating Temperature111 °F
Diameter117 in
Nominal Thickness0.923 in
Corrosion Allowance0.1250 in
H2S / Chloride34 / 3727 ppm
Flow Velocity17.1 ft/s
Process pH7.71
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
2.44 mpy
Predicted corrosion rate under these conditions (+1.16 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 — Chloride Stress Corrosion Cracking (Cl-SCC)

API 571 §4.5.2

Cracking of austenitic stainless steel exposed to chlorides above roughly 140°F under tensile stress; not a thickness-loss mechanism.

Recommended inspection approach: Surface/near-surface NDE (PT, ECT) at susceptible welds and CUI-prone insulated stainless piping; chloride source control.

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 Grid + RT40.8911 in0.8869 in
Mar 1, 2026UT Grid (API 572)40.8887 in0.8832 in
May 3, 2024UT Grid (API 572)40.8906 in0.8822 in
Nov 29, 2022UT Grid (API 572)40.8900 in0.8834 in
Oct 16, 2020UT Grid (API 572)40.8975 in0.8961 in
Jan 4, 2018UT Grid (API 572)40.8970 in0.8925 in
Oct 26, 2015UT Grid (API 572)40.9039 in0.8916 in
Nov 14, 2013UT Grid (API 572)40.9044 in0.8906 in
May 14, 2012UT Spot40.9060 in0.8861 in
Sep 10, 2009UT Grid + RT40.9090 in0.9023 in
Dec 10, 2006UT Spot40.9123 in0.8997 in
Jan 13, 2005UT Grid + RT40.9178 in0.9122 in
Dec 15, 2002UT Spot40.9185 in0.9053 in
Jan 20, 2001UT Spot40.9212 in0.9093 in