Chevron Pascagoula Sustainable Coke Drum Life Extension

© 2019 Chevron. All rights reserved.

Chevron Pascagoula Sustainable Coke Drum Life Extension Planning/Execution

03/11/2020Michael Trahan, Fixed Equipment Reliability

© 2019 Chevron Created by IDC - 2

Summary and Objectives

Discussion Topics• Chevron Pascagoula Coke Drum History Summary

• Critical Step Changes & Focus in Drum Reliability

• Successful Execution of Structure Weld Overlay Repairs

• Sustainable Effort in Drum Life Extension Plan

Key Messages• Early development of a detailed asset strategy plan for future drum deterioration and optimal drum life

extension.

• Full site commitment and agreed upon continuity from all disciplines associated with drum extension plan/process to achieve proper outcome.

• Drum life extension is a sustainable preventive maintenance approach that occurs over time based on physical data and condition basis of the asset requiring continuous inspection/repair efforts.

• Continue to utilize the Delayed Coker Industry as a tool/resource throughout this process for future lesson learned opportunities.

http://in.chevron.com/


Chevron Pascagoula Coke Drum History Summary

1983 – Original plant start-up with 6 Coke Drum (3 Module) operations having tapered wall design and side feed inlet on 24 hour cycle times.Mid-Late 1990’s – Company operations transitioned to start shorter cycle time to 18 hours. In turn, began the multiple failures that resulted in LOC’s and significant amount of unplanned outages with large repair scope. 2003 – New designed and fabricated Coke Drums having uniform wall installed with uninsulated transition spools. In addition, normal operation conditions increased to an aggressive12 hour cycle time.2008/2009 (Total cycles +/- 2,000)

New Chevron ETC designed insulated transition spools and bottom flanges installed.First documented laser scan performed after transition spools/flanges during Module outage in 2009 with minimal amount of bulging identified.

2012/2013 (Total cycles +/- 3,500) Laser scans performed with minimal increase in bulging and severity.Modified quench program to allow for extended initial quench at 300GPM, and additional debottleneck of preheat system in 2013 T/A was improved for drum preheat (Reference trend in additional slide) Minor proactive internal crack repair work performed on drums during TA.

2015/2016 (Total cycles +/- 4,500) Planned laser scan performed on Module revealed significant signs of increased bulging and severity

concerns that weren’t present from 2012. (Assumed feed related due to change in 2013) 1st Q of 2016 was the new drums first LOC that was identified due to weld seam failure at high PSI bulge

creating unplanned outage and OD weld repair scope. The additional two modules had laser scans inspections performed in 2016 revealing comparable bulging

as identified in first module inspection.’ 3rd party consultant utilized to begin development of asset strategy for drum life extension plan.

2018 (Total cycles +/- 5,500) 1st Q of 2018 the second LOC was identified due to weld seam failure at high PSI bulge creating

unplanned outage and OD weld repair scope on same drum that leaked in 2016 2nd Q of 2018 the planned Major TA outage with inspection and SWOL repairs on 6 drums totaling ~4000

plus sq/ft.



Coke Drum Design Information

27’ 7” ID; 77’ tangent to tangent 1.22” Thick C-1/2 Mo Drums with a 0.110” 410SS clad (uniform thickness);

Inco 625 Restoration welds; Inco 625 Weld Overlay on Cone

12 hour cycles: Fill for 12 hours since installation in 2003

Forged Ring Design between shell and cone sections



Effects of Drum Banana and Mitigation Efforts

Drum Banna Representation Since replacement in 2003, signs of lean or potential banana effect has been noted at the outlet piping requiring additional deck modifications to be required.

NOTE: Since the design change and upgrade of the insulated transition spools in 2008/2009, the signs of increased lean or banana has decreased without any additional modifications required.



Pascagoula Refinery Process Changes Supporting Continuous Drum Reliability

Reference the time frame where the initial quench rate was lowered to improve reliability and expected life per industry data. (Top Chart)

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

Tim

e (in

Min

utes

) Bel

ow

325

GPM

300.0

350.0

400.0

450.0

500.0

550.0D

eg F

Increased the preheat temperature to align with drum reliability. Reference the average temperature that is reached 15-30 minutes prior to switch (Bottom Chart)

Industry data and analysis indicates that the most severe conditions occur during the drum cycles are associated with the quench and preheat.

Based on industry learnings Chevron made significant changes to the operations aspect to attempt in sustaining reliability to increase future drum life.



Visual Representation of Significant Step Change in Drum Condition Post 2013 TA Laser scan results from 3rd party company identifying significant increase in bulge number and

severity. (Pre PSI analysis) Signiant feed change occurred after 2013 Major TA, which Chevron believes is large variable in the increased

drum deterioration. Left image - reveals 2D laser scan results with significant amount of changes and deformation. Right image - reveals filtered laser scan results identifying the highest severity bulge locations per

shell course.

2016 Data Revealing Deepest Bulge & Highest Severity Pre PSI Data



Asset Strategy Plan Developed based on PSI Analysis

Industry leading analysis by external consultant that pinpoints areas of concerns and recommended repair locations based on laser scan data.

With adequate acquisition of “raw” laser scanning this analysis will identify areas of the highest strain/stress at either inward and outward bulges locations.



Sustainable Process Approach to Achieve Extended Drum Life 2016 Chevron committed to pursue a drum life extension plan vs. enduring complete drum replacement after

only 15 to 20 year life of the asset.

Plastic Stain Index (PSI) analysis performed was the concept endorsed within Chevron to achieve a proactive and manageable drum life extension plan.

Detailed inspection strategies and defined maintenance activities were established to support the analysis results and planning efforts for future inspection/repair opportunities over multiple years:

Increased laser scan inspection frequencies were established to align with future planned outage opportunities every 12 to 18 months.

Detailed inspection strategy plans for future internal/external locations were developed for validation purposes and identifying high risk locations based on the PSI analysis results.

External insulation modification plans were developed to support the inspection strategy and repair opportunities for future work scope.

Planned 2018 Major TA executed the 1st attempt for Chevron of the structure weld overlay (SWOL) reinforcement strategy based on PSI analysis and physical inspection data.

The TA team executed over 4,000 sq/ft across all 6 drums of the SWOL process utilizing leading repair organization WSI/AZZ.(Reference Pictures in additional slides below)

Final results of repairs made all 6 drums 100% “crack free” based on the extent of the inspections, repairs, and SWOL performed.

100% of high PSI areas were not addressed on all drums due to no physical crack propagation identified. Areas of concern remained unrepaired for future predictable scope to be managed over the course of the committed drum life extension plan.

Established baseline laser scan data immediately following repairs to support future analysis efforts.

2019 follow-up laser scan inspections were performed to achieve PSI data for 2021 and 2022 planned module outage opportunities to continue drum life extension repair strategy.



Coke Drum Bulges



Internal Crack Location Inspection Findings

Typical ID crack location at bimetallic (HAZ of weld)

Severe Elephant Skin Cracking at outward budge Location



External Crack Location Inspection Findings

Outside skirt to forged ring crack with an additional weld external clip crack

External initiated crack due to inward type budge at weld location



External heater pads for Internal weld repairs



Gouging Process & Crack Removal/Repair

Gouging process of 410 cladding and through wall crack removal

Crack repair process prior to applying SWOL



WSI/AZZ Automated Temper bead Structural Weld Overlay Process



Final Overlay Repair Product Internal and External



Laser Scan Results post SWOL Repair

Laser scan data is typically acquired prior to entry during the outages to get the most accurate updates prior to recommending final repair scope.

During the 2018 Major outage Chevron elected to perform a baseline inspection to determine what the condition of the drum showed post SWOL repairs.

The results of the analysis reveal that the bulge severity and high strained locations were addressed to provide adequate baseline for next inspection opportunity.



Future Recommendations/Guidelines to Sustain Asset Strategy Plan

Predetermined asset strategy inspection intervals set based on individual components of the Coke Drum.

Intervals are based on its current condition of deterioration and number of total cycles asset has encountered.



Continued PSI Analysis Approach for High Risk Areas



Future Identified Areas for SWOL Repairs

Planned effort to attempt to perform 12 to 18 month laser scan frequency inspections to stay proactive and ahead of drum deformation unless PSI data shows differently.

Based on the amount of the SWOL and repair scope performed in 2018, predictable scope that remained unrepaired still is expected for potential repairs with minor other changes identified.

The zones identified in yellow represent areas of concerns from the PSI data that will require inspections to be perform to understand the extend of the damage and/or repairs required.

Physical inspection data will provide sufficient data if crack propagation is present that will lead to future risk in LOC due to bulge severity or weld defects.

This data allows Chevron to be more predictable for TA scope when planned module outage opportunities are provided.



Questions and Answers

Thank YouQ&A


Documents

Chevron Pascagoula Sustainable Coke Drum Life Extension