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

ALATAS’ SERVICEENGINEERING / FIELD SERVICE
LOCATION  ASIA/ BRUNIE/ KUALA BELAIT
EQUIPMENT  OFFSHORE CRANES
BRANDFAVELLE FAVCO 7.5/70K

 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

Checking and adjustment

Draining the system oil and cleaning the oil tank

Checking the O-ring

Changing the valves

Testing the crane

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