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V-1334 — Caustic Wash Column V-1334

Sulfur Recovery Unit · Caustic Wash service · Installed Aug 24, 2016 (10 yrs in service)

Low-Medium
Current Min. Thickness
1.898 in
t-min 1.753 in
Measured Corrosion Rate
0.85 mpy
ML-predicted: 1.55 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-240-304L Stainless
Design CodeASME BPVC Section VIII, Div. 1
Joint Efficiency1.00
Design Pressure585 psig
Design Temperature641 °F
Operating Pressure480 psig
Operating Temperature485 °F
Diameter98 in
Nominal Thickness1.920 in
Corrosion Allowance0.0938 in
H2S / Chloride5 / 1942 ppm
Flow Velocity14.8 ft/s
Process pH8.32
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
4.91 mpy
Predicted corrosion rate under these conditions (+4.06 mpy vs. current measured rate)
Implied Remaining Life
29.4 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 + RT41.9128 in1.8976 in
Mar 29, 2025UT Grid + RT41.9080 in1.8933 in
Aug 13, 2023UT Grid (API 572)41.9166 in1.8966 in
Jan 11, 2021UT Grid (API 572)41.9150 in1.8999 in
Jun 18, 2019UT Grid (API 572)41.9163 in1.9099 in