V-1150 — Vacuum Gas Oil Vessel V-1150

Amine Treating Unit · Vacuum Gas Oil service · Installed Sep 1, 1985 (41 yrs in service)

Low-Medium

Current Min. Thickness

0.782 in

t-min 0.725 in

Measured Corrosion Rate

1.95 mpy

ML-predicted: 1.67 mpy

Remaining Life

29.1 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 Efficiency1.00

Design Pressure287 psig

Design Temperature612 °F

Operating Pressure161 psig

Operating Temperature493 °F

Diameter90 in

Nominal Thickness0.863 in

Corrosion Allowance0.0625 in

H2S / Chloride5 / 209 ppm

Flow Velocity7.4 ft/s

Process pH4.76

InsulatedNo

Corrosion & Remaining-Life What-If

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

Operating Temperature493°F

H2S Concentration5 ppm

Chloride Concentration209 ppm

Flow Velocity7.4 ft/s

Process pH4.76

Insulated (CUI potential)

MaterialDamage Mechanism

Live Prediction — What-If Model

8.24 mpy

Predicted corrosion rate under these conditions (+6.29 mpy vs. current measured rate)

Implied Remaining Life

6.9 yrs

Implied Reinspection Interval

3.5 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 Spot	6	0.7849 in	0.7820 in
Jun 24, 2026	UT Grid + RT	6	0.7830 in	0.7643 in
May 7, 2024	UT Grid + RT	6	0.7881 in	0.7689 in
Mar 10, 2022	UT Spot	6	0.7916 in	0.7829 in
Aug 13, 2020	UT Grid (API 572)	6	0.7915 in	0.7757 in
Dec 16, 2018	UT Grid + RT	6	0.7956 in	0.7846 in
Sep 15, 2016	UT Spot	6	0.8047 in	0.8015 in
Dec 16, 2014	UT Grid + RT	6	0.8090 in	0.8057 in
Apr 19, 2012	UT Grid (API 572)	6	0.8105 in	0.8042 in
Mar 24, 2010	UT Grid (API 572)	6	0.8138 in	0.7947 in
Oct 24, 2007	UT Grid + RT	6	0.8148 in	0.8006 in
Nov 2, 2005	UT Spot	6	0.8268 in	0.8167 in
Oct 9, 2003	UT Spot	6	0.8259 in	0.8237 in
Feb 6, 2001	UT Spot	6	0.8327 in	0.8325 in
Jan 10, 1998	UT Grid (API 572)	6	0.8388 in	0.8376 in
Oct 17, 1995	UT Spot	6	0.8449 in	0.8274 in
Feb 18, 1994	UT Spot	6	0.8481 in	0.8459 in
Jan 24, 1992	UT Spot	6	0.8518 in	0.8487 in
May 16, 1989	UT Spot	6	0.8533 in	0.8465 in
Apr 3, 1987	UT Grid + RT	6	0.8599 in	0.8429 in