From 85mm Warpage to Operational: The Rig Jacking System Rescue

Author
Eden Hazard
pubslished on
January 17, 2019
category
Products

Introduction: The Challenge

The Rig, faced a critical juncture in its maintenance lifecycle. Phase 1 of its jacking system remedials was scheduled to address a backlog of known issues, but upon commencement, the true extent of the damage became alarmingly clear. The rig's jacking system—the heart of its ability to position and stabilize—was in a state of severe distress. Multiple units across all three legs exhibited catastrophic levels of wear, distortion, and component failure. With warpage measurements reaching an unprecedented 85mm on some final drives and critical gears found with chipped teeth and severe spalling, the rig's operational integrity and safety were severely compromised. Immediate, expert intervention was required to prevent potential system failure and restore the asset to safe working order.

Project Scope & Objectives

Formura Offshore Services was tasked with executing the Phase 1 remedial campaign on the Rig. The project scope was extensive, covering primary, secondary, and final drive systems across 9 individual units on all three legs.

The primary objectives were:

  • Execute Phase 1 Repairs: Complete all planned overhauls on primary, secondary, and final drive units as per the maintenance schedule.
  • Rectify Catastrophic Damage: Address the extreme levels of wear, distortion, and component failure discovered upon inspection, including final drives with massive warpage and gears with missing teeth.
  • Eliminate Oil Leaks: Replace motor pinion seals on multiple units (B4, C4, D1, F1, I3) to prevent lubricant loss and contamination.
  • Restore OEM Specifications: Dismantle, inspect, and rebuild all units to OEM standards, utilizing spare components where necessary to replace irreparable parts.
  • Ensure Asset Integrity: Return the rig to a fully operational and safe condition, capable of reliable jacking operations.

Key Challenges & Solutions

The Formura team, executed this demanding campaign over a 5-week period (May 8 to June 12, 2024).

Challenge - Extreme Final Drive Distortion: Multiple final drives exhibited catastrophic warpage and uplift. Unit B4 had 70mm warpage and +10mm uplift; Unit F1 had identical 70mm warpage; and Unit G1 had an unprecedented 85mm warpage with +10mm uplift. These conditions made safe operation impossible.

Formura's Solution - Complete System Replacement & Precision Rebuild: The team systematically replaced entire hub and pinion assemblies on these units. On Unit B4, the inboard hub, outboard hub, 7T ¼" P pinion, and 32T bull gear were all replaced with spares. The results were transformative: warpage was reduced from 70mm to just 7mm, and uplift from +10mm to 0.47mm. Unit G1's warpage was corrected to within tolerance with uplift reduced to 0.45mm.

Challenge - Primary Gearboxes with Catastrophic Internal Damage: Units E4 and G1 had primary gearboxes with severe damage. E4 had chipped teeth on primary and final drive gears. G1's 7T 1P output shaft had 3-4mm dents, and the 46T red gear was in poor condition with severe spalling.

Formura's Solution - Complete Gearbox Overhaul: Both gearboxes were fully dismantled. On Unit E4, the team replaced the primary gear, final drive gear, and 7T1P pinion with spares, reusing only the red gear. On Unit G1, they replaced the 7T1P pinion, primary gear, final drive gear, and 46T red gear entirely with spares. All bearings and seals were replaced, restoring the gearboxes to like-new condition.

Challenge - Severe Secondary Drive Deterioration: Secondary drives on units like B4, F1, and G1 exhibited "severe scuffing, severe spalling, and severe abrasive wear" on the 7T ½ P pinions, with hub inserts also in poor condition.

Formura's Solution - Comprehensive Secondary Drive Overhauls: Each secondary unit was completely disassembled. Worn pinions and hub inserts were replaced with spares, and new bearings and seals were installed. Uplift was systematically corrected: Unit B4 reduced from 0.48mm to 0.23mm; Unit G1 reduced from 1.23mm to 0.24mm.

Challenge - Multiple Concurrent Oil Leaks: Units B4, C4, D1, F1, and I3 all required motor pinion seal replacements, indicating a systemic issue with seal integrity.

Formura's Solution - Efficient Seal Replacement Campaign: The team executed all five seal replacements with precision. On Unit I3, they also addressed the final drive, reducing warpage from 33mm to 6mm and uplift from 8.48mm to 0.84mm, demonstrating their ability to combine quick repairs with major overhauls seamlessly.

Project Results

Formura Offshore Services successfully delivered a comprehensive Phase 1 remedial campaign for the Rig, addressing catastrophic damage and restoring the jacking system to full operational integrity within the scheduled anchorage window.

Key Results:

  • 9 Critical Units Restored: All primary, secondary, and final drive systems on the identified units were successfully overhauled, including those with extreme damage.
  • Catastrophic Distortion Corrected: Final drives with unprecedented warpage were brought back into safe tolerance.
    • Unit B4 final drive: Warpage reduced from 70mm to 7mm; Uplift reduced from +10mm to 0.47mm.
    • Unit F1 final drive: Warpage reduced from 70mm to 7mm; Uplift reduced from +10mm to 0.47mm.
    • Unit G1 final drive: Warpage corrected from 85mm; Uplift reduced to 0.45mm.
    • Unit C4 final drive: Warpage reduced from 35mm to 8mm; Uplift reduced from 8.35mm to 0.24mm.
  • Primary Gearboxes Rebuilt: Units E4 and G1 were completely overhauled with multiple component replacements, eliminating the risk of catastrophic gear failure.
  • All Leaks Stopped: Motor pinion oil seals on five units (B4, C4, D1, F1, I3) were successfully replaced, preventing future lubricant loss.
  • Full Operational Readiness Achieved: The Rig was returned to service with a fully restored jacking system, capable of safe and reliable operations.

Conclusion

This project stands as a testament to Formura Offshore Services' capability to handle the most extreme cases of jacking system degradation. Faced with unprecedented levels of warpage (85mm) and catastrophic component damage, the team delivered technically superb solutions that prioritized safety and operational integrity. The successful restoration of the Rig jacking system underscores Formura's position as a trusted partner capable of executing the most demanding offshore repair campaigns, no matter the scale of the damage.