V-1249 — Vacuum Resid Drum V-1249

Amine Treating Unit · Vacuum Resid service · Installed Aug 31, 1989 (37 yrs in service)

High

Current Min. Thickness

0.131 in

t-min 0.274 in

Measured Corrosion Rate

7.05 mpy

ML-predicted: 7.44 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-240 Duplex 2205

Design CodeASME BPVC Section VIII, Div. 1

Joint Efficiency0.85

Design Pressure133 psig

Design Temperature639 °F

Operating Pressure109 psig

Operating Temperature460 °F

Diameter84 in

Nominal Thickness0.401 in

Corrosion Allowance0.0625 in

H2S / Chloride11 / 274 ppm

Flow Velocity12.6 ft/s

Process pH5.23

InsulatedNo

Corrosion & Remaining-Life What-If

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

Operating Temperature460°F

H2S Concentration11 ppm

Chloride Concentration274 ppm

Flow Velocity12.6 ft/s

Process pH5.23

Insulated (CUI potential)

MaterialDamage Mechanism

Live Prediction — What-If Model

9.64 mpy

Predicted corrosion rate under these conditions (+2.59 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	0.1367 in	0.1310 in
Sep 20, 2024	UT Grid + RT	6	0.1367 in	0.1243 in
Aug 18, 2021	UT Spot	6	0.1367 in	0.1269 in
Feb 21, 2019	UT Grid (API 572)	6	0.1367 in	0.1313 in
Dec 10, 2016	UT Grid + RT	6	0.1367 in	0.1354 in
Mar 31, 2014	UT Spot	6	0.1367 in	0.1315 in
May 30, 2012	UT Grid + RT	6	0.1367 in	0.1347 in
Aug 14, 2010	UT Spot	6	0.1367 in	0.1289 in
May 20, 2008	UT Grid + RT	6	0.1367 in	0.1360 in
Nov 19, 2006	UT Grid (API 572)	6	0.1395 in	0.1294 in
Oct 10, 2003	UT Spot	6	0.1852 in	0.1771 in
Oct 12, 2000	UT Grid + RT	6	0.2308 in	0.2303 in
Jan 11, 1998	UT Grid + RT	6	0.2719 in	0.2521 in
Dec 6, 1995	UT Spot	6	0.3047 in	0.2975 in
Jun 11, 1994	UT Grid + RT	6	0.3300 in	0.3205 in
May 24, 1992	UT Grid + RT	6	0.3594 in	0.3504 in