|Alatas Service||Field Service|
|Vessel Type||Diving Support Vessel|
|Crane Type||50t Active Heave Compensation (AHC)|
This overhaul of Haean crane on a diving support vessel is equipped with a 50 ton Active Heave Compensation Offshore Crane.
During a routine slewing bearing assessment carried out by certified Alatas Offshore Crane Engineers, large cracks were detected in the welding seams of the slewing bearing flange at the base column.
The location and the depth of the cracks did not allow for in-situ repairs, but the entire base column had to be removed and shifted into Alatas workshop for the flange repair.
This work necessitated the removal of the crane and later reinstallation and commissioning. Alatas provided project management, engineering, personnel, workshop facilities, and carried out the following tasks on a turnkey basis.
Job Scope for Overhaul of Haean crane
- Crane disassembly and removal of base column from vessel
- Lifting plans designed & calculated by Alatas Lifting Technical Authority
- Removal of crane knuckle boom, main boom and crane slewing chassis
- Removal of base column and transport from vessel to Alatas workshop
- Slewing column flange repair at Alatas workshop
- Drafting repair procedure, submission to class and obtaining class approval
- Supply of materials and fabricating new flange
- Crop-off old, cracked flange and weld new flange
- Drill stud holes
- Carry out in-situ machining to achieve required flange flatness
- Establishing QC & NDT reports and class certification
- Slewing Bearing Inspection and overhaul at Alatas workshop
- Dismantle & inspect slewing bearing
- Carry out crack testing on slewing bearing raceways
- Supply new slewing bearing balls and distance elements and reassemble slewing bearing
- Crane installation and commissioning
- Lifting plans designed and calculated by Alatas Lifting Technical Authority
- Install repaired base column back onto vessel
- Install Slip ring unit into base column
- Assemble crane on ground and prepare crane to be lifted as one, completely assembled unit
- Arrange shear leg crane and lift crane onto base column
- Complete installation, wire rope reeving and carry out crane function testing
- Carry out overload testing and issue test certificate
- Establish full reporting package, including class certification