Agile Offshore Maintenance: Balancing Planned Scope with Emergent Jacking Repairs

Author
Eden Hazard
pubslished on
January 17, 2019
category
Products

Introduction: The Challenge

The Rig, a LeTourneau design jack-up rig, continued its proactive maintenance program with Phase 4 of its jacking system remedials. However, as with any complex offshore asset, the planned scope was only part of the story. The rig faced a combination of pending overhauls, units with significant wear identified in previous inspections, and—critically—a new, urgent issue: a unit in the FWD leg (C4) had begun making an abnormal noise during jacking operations. This emergent problem posed an immediate threat to operational integrity and required swift diagnosis and repair alongside the scheduled Phase 4 work to prevent potential system failure and unplanned downtime.

Project Scope & Objectives

Formura Offshore Services was tasked with executing the Phase 4 remedial campaign on the Rig while simultaneously investigating and rectifying the emergent noise issue. The project scope was dynamic, covering multiple drive systems across 11 individual units, with work extending beyond the original plan based on real-time findings.

The primary objectives were:

  • Execute Phase 4 Scope: Complete all planned overhauls on secondary and final drive units as per the maintenance schedule.
  • Diagnose & Rectify Emergent Issue: Investigate the root cause of the abnormal noise in Unit C4 (FWD Leg) and perform necessary repairs.
  • Address Seal Leaks: Replace motor pinion oil seals on units with active leaks (C2, F2) to prevent lubricant loss and contamination.
  • Restore OEM Specifications: Dismantle, inspect, and rebuild units to LeTourneau OEM methods and standards, replacing worn gears, pinions, hubs, bearings, and seals.
  • Maximize Asset Availability: Complete all work efficiently within the offshore schedule to ensure the rig returned to full operational status without delay.

Key Challenges & Solutions

The Formura team, executed this dynamic campaign over a 5-week period (October 9 to November 13, 2024) in an offshore environment.

Challenge - Emergent "Abnormal Noise" Issue: Unit C4 (FWD Leg) was not in the original work scope, but its disturbing noise during jacking demanded immediate attention to prevent catastrophic failure.

Formura's Solution - Rapid Response & Diagnosis: The team quickly pivoted to investigate the noise. Upon disassembly, they discovered excessive play between the bearing inner diameter and the shaft. By replacing the ½" P pinion, seals, and bearings, they eliminated the noise and reduced uplift from 1.40mm to just 0.20mm, fully restoring the unit.

Challenge - Severe Final Drive Distortion: Multiple final drives (C1, E3, F4, G1, H2) exhibited warpage and uplift far beyond acceptable limits. For example, Unit C1 had 23mm warpage, and Unit G1 had 23mm warpage with 3.88mm uplift.

Formura's Solution - Systematic Overhaul & Realignment: The team meticulously rebuilt each distorted final drive. Severely worn components like inboard/outboard hubs and 7T ¼" P pinions were replaced with spares. The results were dramatic: Unit C1's warpage was reduced from 23mm to 8mm and uplift from 3.72mm to 0.27mm; Unit G1's warpage was reduced to 8mm and uplift to 0.43mm.

Challenge - Spare Parts Constraints: The project faced limitations, with notes indicating that several units (A3, C3, E2, G3, I4 Final Drives) could not be overhauled due to insufficient spares onboard.

Formura's Solution - Strategic Prioritization & Communication: The team worked closely with the OIM and Chief Engineer to prioritize available spares for the most critical repairs. Clear communication ensured the client was fully informed of constraints, allowing for informed decisions on scope execution and future spare procurement planning.

Challenge - Rapid "Quick-Win" Repairs Needed: Oil leaks on motor pinion seals (C2, F2) needed fast, effective resolution to prevent further lubricant loss and potential gear damage.

Formura's Solution - Efficient Seal Replacement: The team executed these repairs with precision and speed. On Unit C2, they replaced both the motor pinion seal and dust shield. On Unit F2, they replaced the seal and also identified a secondary leak from the output shaft, providing the client with valuable diagnostic information for future planning.

Project Results

Formura Offshore Services successfully delivered a comprehensive remedial campaign for the Rig, completing the Phase 4 scope, addressing the emergent noise issue, and executing critical seal repairs within the offshore schedule.

Key Results:

  • 11 Units Addressed:All targeted primary, secondary, and final drive systems were successfully overhauled or repaired, including emergent work on Unit C4.
  • Critical Parameters Restored: Warpage and uplift were corrected across multiple final drives, bringing them back into safe operational tolerance.
    • Unit C1 final drive: Warpage reduced from 23mm to 8mm; Uplift reduced from 3.72mm to 0.27mm.
    • Unit E3 final drive: Warpage reduced from 21mm to 6mm; Uplift reduced from 3.97mm to 0.28mm.
    • Unit F4 final drive: Warpage reduced from 14mm to 6mm; Uplift reduced from 3.54mm to 0.32mm.
  • Abnormal Noise Eliminated: Unit C4 was successfully diagnosed and overhauled, removing the operational threat and ensuring smooth jacking performance.
  • Leaks Stopped: Motor pinion oil seals on Units C2 and F2 were replaced, preventing further lubricant loss and potential contamination.
  • Informed Future Planning: The identification of spare parts shortages and secondary leaks (Unit F2) provided the client with critical data for future procurement and maintenance planning.

Conclusion

This project exemplifies Formura Offshore Services' ability to adapt and deliver in a dynamic offshore environment. By successfully balancing a planned scope (Phase 4) with emergent, high-priority issues (the abnormal noise in Unit C4) and quick-response repairs (seal leaks), the team demonstrated technical excellence, rapid diagnostic capability, and a commitment to the client's operational priorities. The successful restoration of the Rig jacking system further solidifies Formura's reputation as a trusted, agile partner for critical offshore maintenance.