DESIGN, ENGINEERING, AND STRESS ANALYSES OF SLEWING BEARING CHANGEOUT JACKING SYSTEM – 7.5/10K (Serial No. 1205)

INTRODUCTION

Alatas Engineering and Design Services UK has been entrusted by CIC-ALATAS BRUNEI Pvt Ltd on behalf of Brunei Shell Petroleum (BSP) to undertake the design & engineering of a new jacking system for FF 7.5/10K Rope Luffed Offshore Pedestal Crane, which will allow the crane to be jacked up and suspended whilst the slewing bearing changeout is carried out on PORT side for removal of an old and installation of a new slewing bearing.

BACKGROUND

The 705/10K model is a diesel-hydraulic operated, rope-luffed boom crane with a rotating superstructure. It consists of a 31m boom with a maximum capacity of 18.2Te at 23m & 13Te at 31m with a main hoist and a maximum capacity of 5Te with an auxiliary hoist. The crane is designed for use in an offshore environment for offloading and backloading supply vessels and general work on the platform and transfer of personnel.

The slewing bearing’s physical condition had greatly deteriorated to the point it required to be changed out to allow continued safe offshore operation of FF 7.5 /10K Crane.

ALATAS SOLUTION

• The biggest challenge was to design a modular jacking system structure to utilize OEM’s existing 4 nos. slewing bearing changeout brackets and 4 padeyes welded to the crane pedestal to allow the new jacking system to be mounted and supported on an existing pedestal, hence not supported on the platform deck structure.
• As identified and discussed with the client, there was a narrow clearance for the slewing bearing during the changeout process based on the outside diameter of the slewing bearing and the vertical jacking columns on the port side. The ultimate solution was made to incorporate sufficient clearance for the slewing bearing changeout.
• It was aimed to design a modular jacking system structure that can be used with other cranes (Model FF 200RL) jacking structure.
• The structural strength assessment has been carried out to meet the allowable stress design criteria of LR’s CLAME 2019 and crane jacking loads for the highest vertical dead loads & most unfavorable environmental wind horizontal force.
• The primary members of the jacking structure of the crane have exhibited equivalent von mises stresses and resulting deformation within the allowable limit of material of construction and design code.
• The new jacking structure is designed as per supplied information & requirements and is suitable for use with FF 7.5/10K Rope Luffed Offshore Pedestal Crane for the desired purpose of slewing bearing changeout on the port side of the cranes according to AEDS worked out design loads and supplied manufacturing/fabrication drawings

FULL WORK SCOPE

Alatas AEDS UK performed the following core scope of work under its proposal for the design and engineering of a modular jacking system structure with as many interchangeable manufacturing & fabrication parts as possible.

Design & Engineering

• Review crane and platform historical data.
• Determine the most suitable jacking method (deck supported or pedestal mounted jacking system option).
• 3D Modelling of the crane to establish the center of gravity.
• Engineering stability checks of the jacked-up crane to allow slewing bearing changeout.
• Design of a modular jacking structure system to suit pedestal changeout brackets and padeyes design by OEM.

Third-Party Review & Approval

• Preparation of engineering calculations, fabrication drawings, and design package book for DNV review & approval.
• Meetings and technical discussions with Interface businesses, clients, and DNV.

DESIGN, ENGINEERING, AND STRESS ANALYSES OF SLEWING BEARING CHANGEOUT JACKING SYSTEM – 7.5/10K (Serial No. 1205) Gallery