Alimak Hek Extends the Life of Four U500 Elevators On-Board the Ocean Apex

U500 elevator refurbishment

Alimak Hek has completed the refurbishment and installation of four Alimak U500 industrial elevators on-board Diamond Offshore’s Ocean Apex, extending the operating life of the elevators.

Diamond Offshore’s newly named semi-submersible vessel has undergone a large capital upgrade in Singapore’s Jurong Shipyard. Scheduled for completion in the year’s third quarter, the refurbished semi-submersible is designed with depth capacities of 6,000ft and a drilling depth of 30,000ft to meet the rising demand for deepwater drilling rigs.

In February, Alimak Hek completed the refurbishment and installation of four Alimak U500 rack and pinion industrial elevators located within the rig’s service and maintenance shafts. Travelling 40m below deck via each of the rig’s column legs, the elevators provide crucial maintenance access to the lower pump rooms and ballast areas.

Given the relative age and extremely harsh marine environment of the rig, the original Alimak U500 elevators had become corroded and damaged beyond repair through exposure to salt, damp and humidity.

Upon inspection of the elevators, Alimak Hek identified that two of the elevators, the PC2 and SC2, were damaged beyond repair and would require a complete refurbishment. The remaining elevators, the CPC4 and CSC4, remained in a reasonably good condition. These could undergo only an electrical refurbishment.

Ocean Apex project manager Jon Shoemaker said: "Alimak Hek was very professional in evaluating our scope of work after the initial rig survey. The easy answer could have been to replace everything, yet Alimak did a great job in placing an objective evaluation, while keeping in mind the value for money concept to the customer."

In order to preserve the uniformity of all four elevators and make use of the undamaged original mast and rack sections, the Alimak Hek refurbishment department used original elevator designs to manufacture two completely identical U500 elevators for installation on the existing mast and rack. In replicating the original elevator designs, Alimak Hek was able to manufacture the new U500 elevators to the exact specifications of those that were damaged, creating a perfect fit between the newly refurbished elevator cars and the existing mast and rack sections.

Manufacturing replicas of the original Alimak U500 elevators also solved space issues on the rig. Given the extremely limited space available within each column’s elevator shaft, the U500 was the only elevator that could be configured to fit the tight space. With a car size of only 0.8m2, each U500 elevator is capable of transporting two people, or a maximum capacity of 1000kg, 40m between the rig’s top and bottom landings.

During the electrical refurbishments, each of the CPC4 and CSC4 elevators were equipped with direct on line motors with new base / main electrical panels, call stations, limit switches and gearboxes, with the busbar on all four elevators removed to allow for the safer and more efficient supply of electricity. As a result, all four of the Alimak U500 elevators on-board the Ocean Apex now operate on a uniform set of electricals and standard electrical supply.

"The team members from the Alimak Hek Australia division were very safety conscious, professional and obliging in the midst of a complicated job," added Shoemaker. "The Alimak team worked very well in navigating through the rough waters of Diamond as a customer and the JSPL shipyard for support. The team was able to maintain a professional attitude that was key to their success in the midst of such a challenging situation."

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