V-1212 — Crude Oil Column V-1212

Alkylation Unit · Crude Oil service · Installed Aug 30, 1994 (32 yrs in service)

Critical

Current Min. Thickness

0.730 in

t-min 1.012 in

Measured Corrosion Rate

13.55 mpy

ML-predicted: 14.10 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-387-11 Cl.2 (1.25Cr-0.5Mo)

Design CodeASME BPVC Section VIII, Div. 2

Joint Efficiency1.00

Design Pressure327 psig

Design Temperature425 °F

Operating Pressure290 psig

Operating Temperature340 °F

Diameter109 in

Nominal Thickness1.174 in

Corrosion Allowance0.1250 in

H2S / Chloride19 / 227 ppm

Flow Velocity9.1 ft/s

Process pH7.43

InsulatedNo

Corrosion & Remaining-Life What-If

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

Operating Temperature340°F

H2S Concentration19 ppm

Chloride Concentration227 ppm

Flow Velocity9.1 ft/s

Process pH7.43

Insulated (CUI potential)

MaterialDamage Mechanism

Live Prediction — What-If Model

11.99 mpy

Predicted corrosion rate under these conditions (-1.56 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 — Naphthenic Acid Corrosion

API 571 §4.2.10

Aggressive, velocity-assisted corrosion in high-TAN crude fractions, most severe 450–750°F; low-alloy/carbon steel is far more susceptible than Mo-bearing or 316 SS.

Recommended inspection approach: UT thickness at high-velocity/turbulent locations; feed TAN monitoring; consider alloy upgrade per API 571 guidance.

Inspection History

UT thickness readings, most recent first

Date	Method	CML Count	Avg Thickness	Min CML Thickness
Aug 22, 2026	UT Grid + RT	6	0.7356 in	0.7303 in
Sep 15, 2025	UT Grid (API 572)	6	0.7535 in	0.7453 in
Oct 2, 2023	UT Grid (API 572)	6	0.7826 in	0.7752 in
Oct 23, 2020	UT Spot	6	0.8199 in	0.8077 in
Sep 29, 2017	UT Spot	6	0.8623 in	0.8490 in
May 12, 2015	UT Grid (API 572)	6	0.8933 in	0.8771 in
Sep 7, 2012	UT Grid (API 572)	6	0.9326 in	0.9316 in
Mar 20, 2010	UT Grid (API 572)	6	0.9610 in	0.9440 in
Jan 25, 2007	UT Grid (API 572)	6	1.0038 in	0.9869 in
Apr 18, 2005	UT Grid (API 572)	6	1.0293 in	1.0105 in
Jan 28, 2002	UT Spot	6	1.0733 in	1.0722 in
Sep 10, 1999	UT Grid (API 572)	6	1.1048 in	1.1005 in
Aug 20, 1996	UT Grid + RT	6	1.1478 in	1.1427 in