V-1133 — Crude Oil Drum V-1133

Delayed Coker · Crude Oil service · Installed Sep 1, 1984 (42 yrs in service)

Medium

Current Min. Thickness

0.581 in

t-min 0.531 in

Measured Corrosion Rate

1.29 mpy

ML-predicted: 1.26 mpy

Remaining Life

38.8 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-516-70 Carbon Steel

Design CodeASME BPVC Section VIII, Div. 2

Joint Efficiency0.85

Design Pressure444 psig

Design Temperature223 °F

Operating Pressure248 psig

Operating Temperature209 °F

Diameter40 in

Nominal Thickness0.644 in

Corrosion Allowance0.0625 in

H2S / Chloride43 / 184 ppm

Flow Velocity7.9 ft/s

Process pH5.37

InsulatedNo

Corrosion & Remaining-Life What-If

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

Operating Temperature209°F

H2S Concentration43 ppm

Chloride Concentration184 ppm

Flow Velocity7.9 ft/s

Process pH5.37

Insulated (CUI potential)

MaterialDamage Mechanism

Live Prediction — What-If Model

6.91 mpy

Predicted corrosion rate under these conditions (+5.62 mpy vs. current measured rate)

Implied Remaining Life

7.2 yrs

Implied Reinspection Interval

3.6 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 Spot	6	0.5897 in	0.5807 in
May 15, 2025	UT Spot	6	0.5914 in	0.5778 in
Apr 5, 2023	UT Grid + RT	6	0.5931 in	0.5754 in
Oct 2, 2021	UT Grid + RT	6	0.5954 in	0.5788 in
Aug 22, 2018	UT Grid + RT	6	0.5943 in	0.5818 in
Apr 25, 2016	UT Grid (API 572)	6	0.6061 in	0.6010 in
Jan 15, 2013	UT Grid + RT	6	0.6090 in	0.5976 in
Nov 29, 2009	UT Spot	6	0.6135 in	0.5973 in
Jan 24, 2007	UT Grid + RT	6	0.6188 in	0.6157 in
Aug 26, 2005	UT Grid (API 572)	6	0.6163 in	0.6047 in
Mar 5, 2003	UT Spot	6	0.6172 in	0.6054 in
Jun 7, 2000	UT Grid + RT	6	0.6230 in	0.6085 in
Dec 13, 1998	UT Grid + RT	6	0.6248 in	0.6063 in
Sep 16, 1996	UT Grid + RT	6	0.6268 in	0.6174 in
Aug 22, 1994	UT Grid + RT	6	0.6297 in	0.6192 in
Jan 24, 1992	UT Grid (API 572)	6	0.6357 in	0.6174 in
Dec 8, 1988	UT Grid + RT	6	0.6396 in	0.6357 in
Apr 9, 1987	UT Spot	6	0.6386 in	0.6207 in