V-1003 — Vacuum Gas Oil Drum V-1003

Hydrocracker · Vacuum Gas Oil service · Installed Aug 30, 1995 (31 yrs in service)

Low-Medium

Current Min. Thickness

0.882 in

t-min 0.780 in

Measured Corrosion Rate

0.67 mpy

ML-predicted: 1.39 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-516-70 Carbon Steel

Design CodeASME BPVC Section VIII, Div. 1

Joint Efficiency0.85

Design Pressure501 psig

Design Temperature209 °F

Operating Pressure305 psig

Operating Temperature141 °F

Diameter52 in

Nominal Thickness0.913 in

Corrosion Allowance0.0625 in

H2S / Chloride38 / 260 ppm

Flow Velocity3.5 ft/s

Process pH7.10

InsulatedNo

Corrosion & Remaining-Life What-If

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

Operating Temperature141°F

H2S Concentration38 ppm

Chloride Concentration260 ppm

Flow Velocity3.5 ft/s

Process pH7.1

Insulated (CUI potential)

MaterialDamage Mechanism

Live Prediction — What-If Model

6.28 mpy

Predicted corrosion rate under these conditions (+5.61 mpy vs. current measured rate)

Implied Remaining Life

16.3 yrs

Implied Reinspection Interval

8.1 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	0.8933 in	0.8822 in
Mar 5, 2026	UT Grid (API 572)	6	0.8932 in	0.8788 in
Dec 30, 2023	UT Spot	6	0.8909 in	0.8884 in
May 30, 2021	UT Grid (API 572)	6	0.8961 in	0.8824 in
Jun 10, 2019	UT Spot	6	0.8937 in	0.8772 in
May 17, 2017	UT Grid + RT	6	0.9004 in	0.8951 in
Jun 17, 2014	UT Spot	6	0.8972 in	0.8838 in
Jul 6, 2012	UT Grid (API 572)	6	0.9005 in	0.8986 in
May 1, 2009	UT Grid + RT	6	0.9037 in	0.8892 in
Jul 1, 2006	UT Spot	6	0.9060 in	0.8980 in
Nov 24, 2004	UT Grid (API 572)	6	0.9097 in	0.9040 in
Sep 12, 2002	UT Spot	6	0.9060 in	0.8997 in
Jan 10, 2001	UT Grid + RT	6	0.9087 in	0.8937 in
Jun 28, 1998	UT Spot	6	0.9098 in	0.8939 in