Offshore staff
ABERDEEN, UK – EnerMech has replaced a slew bearing for the north crane on the BP-operated Chirag 1 platform offshore Azerbaijan.
The mechanical engineering specialist, working with BP’s structural team, designed a special jacking frame. Following tests at EnerMech’s Baku yard, all equipment and materials were shipped offshore.
One of the first major tasks was to align the jacking frame legs with the pedestal of the crane. Four jacking pads were welded onto the pedestal and the underside of the crane chassis, and a habitat was built around the frame to allow welding to begin.
Following magnetic particle inspection of the welds, the final assembly of the jacking frame was constructed using four 75-metric ton (83-ton) hydraulic jacks placed within the jacking frame legs.
The jacking structure was overload tested to ensure integrity of the welds and bolts, and the 56-metric ton (62-ton) crane chassis was then lifted to a height of 500 mm (19.7 in.).
Next, lasers were used to check the pedestal face and the underside of the crane chassis for flatness, with readings confirmed as being within the acceptable tolerances for the new slew bearing.
The latter was pulled onto the pedestal of the crane, ensuring that the bearing’s “soft spot” of the bearing was positioned 90° to the load path of the crane. In a reverse procedure of the jacking operation, the crane chassis was slowly lowered onto the new bearing, after which new slew bolts were inserted and torqued to the OEM specifications.
04/14/2015
