V-1328 — Caustic Wash Drum V-1328

Catalytic Reformer · Caustic Wash service · Installed Sep 1, 1987 (39 yrs in service)

Low-Medium

Current Min. Thickness

0.699 in

t-min 0.597 in

Measured Corrosion Rate

0.90 mpy

ML-predicted: 2.43 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. 2

Joint Efficiency0.85

Design Pressure233 psig

Design Temperature696 °F

Operating Pressure175 psig

Operating Temperature520 °F

Diameter72 in

Nominal Thickness0.751 in

Corrosion Allowance0.1250 in

H2S / Chloride10 / 3174 ppm

Flow Velocity2.9 ft/s

Process pH5.54

InsulatedNo

Corrosion & Remaining-Life What-If

Adjust operating conditions to see the live model-predicted corrosion rate and implied remaining life

Operating Temperature520°F

H2S Concentration10 ppm

Chloride Concentration3174 ppm

Flow Velocity2.9 ft/s

Process pH5.54

Insulated (CUI potential)

MaterialDamage Mechanism

Live Prediction — What-If Model

3.36 mpy

Predicted corrosion rate under these conditions (+2.46 mpy vs. current measured rate)

Implied Remaining Life

30.4 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

Date	Method	CML Count	Avg Thickness	Min CML Thickness
Aug 22, 2026	UT Grid + RT	6	0.7146 in	0.6990 in
Sep 20, 2025	UT Grid + RT	6	0.7162 in	0.7058 in
Oct 17, 2023	UT Grid (API 572)	6	0.7197 in	0.7101 in
Sep 21, 2021	UT Grid (API 572)	6	0.7176 in	0.7065 in
Aug 11, 2018	UT Grid + RT	6	0.7243 in	0.7218 in
Dec 10, 2015	UT Grid (API 572)	6	0.7257 in	0.7238 in
May 27, 2014	UT Grid (API 572)	6	0.7278 in	0.7223 in
Sep 11, 2012	UT Spot	6	0.7247 in	0.7079 in
Dec 16, 2010	UT Grid (API 572)	6	0.7283 in	0.7260 in
Jun 20, 2009	UT Grid + RT	6	0.7305 in	0.7189 in
Jun 8, 2007	UT Grid + RT	6	0.7328 in	0.7216 in
May 9, 2005	UT Grid (API 572)	6	0.7304 in	0.7112 in
Jun 10, 2003	UT Grid + RT	6	0.7368 in	0.7322 in
Jul 2, 2000	UT Spot	6	0.7412 in	0.7399 in
Jan 18, 1999	UT Spot	6	0.7411 in	0.7215 in
Oct 17, 1995	UT Spot	6	0.7452 in	0.7443 in
Sep 13, 1993	UT Spot	6	0.7459 in	0.7354 in
Apr 18, 1991	UT Grid + RT	6	0.7459 in	0.7319 in
Oct 13, 1989	UT Grid + RT	6	0.7462 in	0.7286 in