150+ Keyhole Repairs Under Live Discovery Conditions

Managing Expanding Coke Drum Scope Without Schedule Loss

During a Northern European refinery turnaround, routine inspection of two coke drums escalated into a high-volume defect remediation program. More than 150 keyholes were identified, with additional cracking revealed as repairs progressed.

This scope became a live discovery environment requiring real-time engineering decisions, controlled execution, and disciplined prioritisation.

 

Why Keyhole Repairs Escalate

In coke drums operating under severe cyclic thermal fatigue, small surface defects often indicate deeper stress-driven damage. Once excavation begins, additional cracking may be exposed at:

  • Weld toes
  • Restoration welds
  • ID/OD transition zones
  • Previously repaired areas

Under turnaround constraints, the risk is not only structural, but schedule-driven. Each new indication has the potential to disrupt sequencing and manpower allocation.

Effective execution depends on rapid defect characterization and immediate selection of the correct repair methodology.

Scope of Work

  • 150+ keyhole repairs across two drums
  • Weld repair, drilling, and controlled opening methods
  • OD and ID crack remediation
  • Localized ID overlay repairs
  • Parallel execution on both units

The volume of defects required a structured approach to avoid inspection bottlenecks and resource congestion.

 

Engineering Controls in a Discovery-Driven Environment

Each indication was assessed for:

  • Crack depth and orientation
  • Fatigue versus superficial origin
  • Structural relevance
  • Suitability for localized weld repair versus overlay

Engineering oversight enabled immediate decision-making.

 

Parallel ID and OD Work Fronts

To protect the turnaround schedule:

  • Internal and external repair teams operated simultaneously
  • QA/QC hold points were staggered
  • Workforce deployment was dynamically adjusted as scope evolved

Parallelisation reduced idle time while maintaining inspection integrity.

 

Adaptive Workforce Deployment

As new defects were uncovered, repair sequencing was continuously rebalanced.

This prevented clustering of inspection activities and ensured that:

  • Welding crews remained productive
  • Inspection teams avoided backlog
  • Critical-path work was protected

Discovery-driven projects reward flexibility, but only when supported by engineering governance.

 

Strict HSE Compliance

All repairs were executed within a high-regulation refinery environment under stringent HSE requirements.

Increased personnel density and parallel activities were managed without compromising safety performance.

The Outcome

  • 150+ keyholes successfully repaired
  • ID and OD cracking mitigated
  • Overlay applied where structurally required
  • Scope expansion absorbed without schedule disruption
  • Both drums returned to service within turnaround window

 

Project Manager: Antoni Zarychta – View Profile
Site Supervisor: Roger Matos – View Profile
Foreman: Piotr Rychlik – View Profile
Welding Engineering: André Roodzant – View Profile

Learn more about coke drum damage mechanisms and welding controls.

 

 

Want to know more?

Connect with our experts at [email protected] or by sending us a message below.

 

Send us a message

 

WATCH VIDEO:  Automated Weld Overlay