Restoring Rig Mobility: A Complex Offshore Repair Success Story

Author
Eden Hazard
pubslished on
January 17, 2019
category
Products
Restoring Rig Mobility: Overcoming Critical Jacking Failures

Introduction: The Challenge

We face significant operational challenges with the rig. A series of pending overhauls from a previous shipyard project, compounded by damage sustained during jacking operations, had left critical components of the rig's jacking system in a state of failure. Multiple transverse skidding units across the Forward, Starboard, and Port legs were experiencing oil leaks, damaged seals, and in severe cases, sheared gears and worn-out hubs. These issues posed a direct threat to the rig's stability, mobility, and overall operational integrity, requiring immediate and expert remedial action.

Project Scope & Objectives

Formura Offshore Services was tasked with executing a comprehensive repair campaign to restore the full functionality of the rig's jacking system. The project scope was extensive and involved:

  • Primary Drive Repairs: Replacing motor pinion seals on multiple units (C1, D3, H2, J2, J4, K4) to eliminate oil leaks and ensure proper lubrication.
  • Final Drive Overhauls: Conducting major repairs on the final drive systems, specifically for units C1 and G3, which had suffered catastrophic failures including a cropped 32T bull gear and a sheared 7T ¼ P climbing pinion.
  • Transverse Skidding Unit Assistance: Supporting the rig's maintenance team in the overhaul of the Rig Floor Transverse Skidding unit's primary drive and upper secondary gear case.
  • Overall Objective: To complete all pending and new repairs efficiently, ensuring the rig could be safely and reliably positioned, despite the constraints of an offshore environment and a prior cyclone alert.

Key Challenges & Solutions

The Formura team, navigated several critical challenges:

  • Challenge 1: Severe Component Damage. Unit C1's bull gear was cropped and stuck in the housing, with a worn-out inboard hub and damaged threads on the outboard hub.
  • Solution: The team expertly installed a new 32T bull gear, a new pinion, and a new inboard hub. They salvaged the damaged outboard hub by rebuilding it and welding new nuts to secure the assembly, demonstrating innovative on-site machining and repair capabilities.
  • Challenge 2: Spare Parts Unavailability. Critical spares for units like G3 and H2 were not available on-site, which could have halted progress indefinitely.
  • Solution: The team adopted a phased approach. They fully dismantled and inspected the units, prepared them for assembly, and safely secured them until spares arrived. For Unit H2's secondary drive, they identified excessive wear (0.053" uplift) and, following client instructions due to a cyclone alert, closed the unit for future repair without compromising immediate safety.
  • Challenge 3: Complex Multi-Unit Overhaul. The project required simultaneous work on seven different jacking units and the transverse skidder, each with unique issues.
  • Solution: Meticulous planning and execution ensured each unit was systematically addressed. The team methodically replaced seals, inspected gears and bearings, and reassembled systems in strict adherence to OEM methods, ensuring quality and reliability across all repairs.

Project Results & Conclusion

The project was completed successfully within the scheduled timeframe. The key results were:

  • 100% Scope Completion: All planned remedial work on the seven jacking units was finished, resolving oil leaks and restoring mechanical integrity.
  • Successful System Test: The complete overhaul of the Rig Floor Transverse Skidding unit was validated when the entire rig package was skidded to the extreme port side "without any issues," a clear testament to the quality of the repairs.
  • Enhanced Operational Readiness: The rig was returned to a fully operational state, with its critical jacking system restored to safe and reliable working order.

Conclusion

Formura Offshore Services delivered a robust technical solution under challenging offshore conditions. By combining expert craftsmanship, adaptive problem-solving, and a strict commitment to safety and OEM standards, the team successfully rectified complex system failures, minimized client downtime, and ensured the continued operational capability of the rig. This project underscores Formura's capability as a trusted partner for critical offshore repair and maintenance operations.