V-1042 — Hydrotreater Feed Drum V-1042

Crude Distillation Unit · Hydrotreater Feed service · Installed Aug 30, 1993 (33 yrs in service)

Medium

Current Min. Thickness

0.759 in

t-min 0.700 in

Measured Corrosion Rate

0.50 mpy

ML-predicted: 0.02 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 Pressure508 psig

Design Temperature125 °F

Operating Pressure403 psig

Operating Temperature102 °F

Diameter46 in

Nominal Thickness0.789 in

Corrosion Allowance0.0625 in

H2S / Chloride3 / 90 ppm

Flow Velocity2.1 ft/s

Process pH8.85

InsulatedNo

Corrosion & Remaining-Life What-If

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

Operating Temperature102°F

H2S Concentration3 ppm

Chloride Concentration90 ppm

Flow Velocity2.1 ft/s

Process pH8.85

Insulated (CUI potential)

MaterialDamage Mechanism

Live Prediction — What-If Model

0.10 mpy

Predicted corrosion rate under these conditions (-0.40 mpy vs. current measured rate)

Implied Remaining Life

60+ yrs

Implied Reinspection Interval

10.0 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 Grid + RT	6	0.7771 in	0.7588 in
Feb 1, 2026	UT Grid (API 572)	6	0.7795 in	0.7790 in
Dec 12, 2023	UT Grid (API 572)	6	0.7796 in	0.7738 in
Dec 12, 2021	UT Grid + RT	6	0.7782 in	0.7675 in
Feb 24, 2019	UT Spot	6	0.7830 in	0.7755 in
Feb 2, 2017	UT Spot	6	0.7787 in	0.7725 in
Jan 16, 2014	UT Grid (API 572)	6	0.7841 in	0.7820 in
Aug 9, 2012	UT Grid + RT	6	0.7808 in	0.7748 in
Jan 6, 2011	UT Grid (API 572)	6	0.7875 in	0.7677 in
Jan 30, 2008	UT Grid + RT	6	0.7833 in	0.7642 in
Nov 29, 2005	UT Spot	6	0.7848 in	0.7810 in
Jan 17, 2004	UT Grid + RT	6	0.7843 in	0.7694 in
Jul 19, 2001	UT Grid (API 572)	6	0.7864 in	0.7798 in
Mar 25, 1999	UT Grid + RT	6	0.7834 in	0.7789 in
Apr 15, 1996	UT Grid + RT	6	0.7847 in	0.7649 in