Slew Bearing & Gearbox Change-Out using a custom Jacking System

 Intro

Our joint venture in Brunei, “CIC-Alatas,” recently replaced the slew bearing on our client’s Favelle Favco 7.5/10k pedestal crane. As this was the first time the slew bearing had been changed, a comprehensive plan had to be devised, built, and the project had to be delivered as a fully turn-key solution.

This was the first of two cranes that need to have their slew bearings replaced using a jacking system and as such Alatas offered a modular design solution where +75% of components were interchangeable between the different crane configurations.

BACKGROUND

‘CIC-Alatas’ hold an operations and maintenance contract covering over 80 offshore cranes with our client. Every crane is subject to a 6-year comprehensive overhaul as part of the maintenance strategy delivery. Because the slew bearing on this crane has never been replaced before, the customer decided to replace it with a new one. This enables a new datum to be recorded of the state of the crane, which can then be used in a redesigned maintenance strategy that places a higher emphasis on condition monitoring.

ALATAS’ SOLUTION

Alatas’s response was to offer a full turnkey solution leveraging multi-office working to guarantee that our client received high-quality and efficient service.

• CIC-Alatas engineering team completed the initial site survey of the crane to gather crucial information to allow the design process to be completed.

• Alatas UK design team developed the jacking system solution.

• Alatas Singapore fabricated the jacking system’s structural components.

• Alatas Indonesia supplied the specialist jacking console and hydraulic cylinders.

• CIC-Alatas engineering team produced the detailed work packs and RAMS.

• CIC-Alatas engineers and field service techs completed the full onshore trials and offshore delivery of the project.

Job Scope

Jacking Frame Design

• Review crane data and select the most suitable jacking method
• 3D Model Crane
• Design Jacking Frame around the design and dimensions of the crane Pedestal and Chassis
• Check Stress Valves using predicted loads
• Design a skidding frame to allow efficient replacement of slew bearing

Jacking Frame Fabrication

• Establish ITP and Quality Plans
• Fabricate Jacking Frame
• Supply of all Fixings
• NDT and Testing
• Provision of Manufacturing Record Book and Certification Pack

Jacking Frame Construction

• Manage construction of Access and Load Bearing Scaffolding
• Lift Plan and Rigging for lifting Jacking Frame Components into position
• Assemble and Test the Jacking System
• Pre and Post NDT of Welds

Slew Bearing Changeout

• Disconnect and Remove of Slip Ring
• Remove both Slew Motors, Brake Packs, and Gearboxes
• Remove Slew Bolts
• Controlled Trial Lift to determine the Centre of Gravity
• Jack Up Crane
• Check Pedestal Flatness using Laser and provide a condition report
• Remove Old Slew Bearing and Install New Slew Bearing
• Jack Crane Back Down
• Install and Tension Inner and Outer Slew Bolts (Rotabolts)
• Re-Connect Slip Ring

Commissioning

• Full Visual Inspection
• Backlash, Rocking Motion, and Teeth Flank Contact Check completed
• Function Test
• Load Test using water bags and load cell

Slew Bearing & Gearbox Change-Out using a custom Jacking System Gallery

Checking and adjustment

Draining the system oil and cleaning the oil tank

Checking the O-ring

Changing the valves

Testing the crane