V-1277 — Crude Oil Column V-1277

Fluid Catalytic Cracker · Crude Oil service · Installed Sep 1, 1985 (41 yrs in service)

Critical

Current Min. Thickness

0.594 in

t-min 0.660 in

Measured Corrosion Rate

5.90 mpy

ML-predicted: 6.39 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-387-11 Cl.2 (1.25Cr-0.5Mo)

Design CodeASME BPVC Section VIII, Div. 1

Joint Efficiency1.00

Design Pressure220 psig

Design Temperature427 °F

Operating Pressure133 psig

Operating Temperature370 °F

Diameter106 in

Nominal Thickness0.836 in

Corrosion Allowance0.1250 in

H2S / Chloride32 / 105 ppm

Flow Velocity3.2 ft/s

Process pH7.34

InsulatedNo

Corrosion & Remaining-Life What-If

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

Operating Temperature370°F

H2S Concentration32 ppm

Chloride Concentration105 ppm

Flow Velocity3.2 ft/s

Process pH7.34

Insulated (CUI potential)

MaterialDamage Mechanism

Live Prediction — What-If Model

4.61 mpy

Predicted corrosion rate under these conditions (-1.29 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 — High-Temperature Sulfidation

API 571 §4.2.11

Reaction of sulfur compounds with steel at high temperature (>500°F) in the absence of water; rate governed by sulfur content, temperature, alloy content.

Recommended inspection approach: UT thickness per Modified McConomy-curve risk ranking; RT/UT at known high-rate locations identified by process simulation.

Inspection History

UT thickness readings, most recent first

Date	Method	CML Count	Avg Thickness	Min CML Thickness
Aug 22, 2026	UT Spot	6	0.5955 in	0.5941 in
Mar 11, 2025	UT Grid (API 572)	6	0.6017 in	0.5844 in
Oct 24, 2023	UT Grid + RT	6	0.6097 in	0.5909 in
Aug 23, 2021	UT Spot	6	0.6217 in	0.6119 in
Jan 5, 2020	UT Spot	6	0.6309 in	0.6295 in
Nov 21, 2017	UT Spot	6	0.6460 in	0.6359 in
Aug 11, 2014	UT Grid + RT	6	0.6664 in	0.6486 in
Jan 12, 2012	UT Grid + RT	6	0.6831 in	0.6746 in
Jul 30, 2010	UT Grid + RT	6	0.6882 in	0.6749 in
Jan 29, 2008	UT Spot	6	0.7062 in	0.7013 in
May 10, 2005	UT Grid (API 572)	6	0.7178 in	0.7118 in
Dec 20, 2003	UT Grid + RT	6	0.7279 in	0.7172 in
Feb 22, 2001	UT Grid (API 572)	6	0.7428 in	0.7380 in
Feb 5, 1999	UT Grid (API 572)	6	0.7541 in	0.7474 in
May 3, 1997	UT Grid (API 572)	6	0.7695 in	0.7608 in
Apr 4, 1995	UT Spot	6	0.7787 in	0.7629 in
Nov 13, 1993	UT Spot	6	0.7851 in	0.7679 in
May 9, 1992	UT Spot	6	0.7952 in	0.7906 in
Jun 22, 1989	UT Grid (API 572)	6	0.8164 in	0.8134 in
May 4, 1987	UT Grid (API 572)	6	0.8246 in	0.8054 in