Alimak Hek extends life of Ocean Apex elevators

Ocean Apex at Jurong Shipyard

APRIL 28, 2014 — Alimak Hek has complete the refurbishment and installation of four Alimak U500 industrial elevators on board Diamond Offshore’s Ocean Apex, extending the operating life of each elevator.

Diamond Offshore’s newly named Ocean Apex semisubmersible has been undergoing a large capital upgrade in Singapore’s Jurong Shipyard.

Scheduled for completion in third quarter 2014, the refurbished semi-sub is designed with depth capacities of 6,000 ft and a drilling depth of 30,000 ft to meet the rising demand for deep-water drilling rigs.

In February 2014, 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. Traveling 40 m 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 two of the elevators, the PC2 and SC2, as damaged beyond repair and would require a complete refurbishment. The remaining elevators, the CPC4 and CSC4, remained in a reasonably good condition; these elevators would undergo only an electrical refurbishment.

Jon Shoemaker, project Manager on the Ocean Apex, explains, “Alimak Hek was very professional in evaluating our SOW (scope of works) 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 on the SOW, while keeping in mind the ‘value for money’ concept to the customer.”

The years and the salt water environment had taken their toll on the elevator cars

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.

Alimak Hek was able to refurbish two of the elevators and manufactured replacements for the other two, using the original elevator designs

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 0.8 metres squared, each U500 elevator is capable of transporting two people, or a maximum capacity of 1000 kg, 40 m between the rig’s top and bottom landings.

With both the PC2 and SC2 elevators undergoing complete refurbishment, the lesser-damaged CPC4 and CSC4 elevators required only electrical refurbishment to bring the supply of the original elevators in line with the electrical supply of the newly refurbished U500s.

During the electrical refurbishments, each of the CPC4 and CSC4 elevators were equipped with DOL (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 to the elevators.

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.

To complete refurbishment works, all four elevators cars had to be completely removed from within the extremely tight elevator shafts. With limited space available to maneuver the elevator cars, penetrations were cut into the side of each column leg, allowing the Alimak U500s to be carefully removed from the shafts using manual winching equipment.

Once refurbishment of the machines was complete, portions of the rack and mast within each column were removed to allow the newly refurbished U500 elevators to be hand-maneuvered back into place.

Refurbishment works on the Alimak U500s on board the Ocean Apex were completed in February 2014.

“The team members from the Alimak Hek Australia division were very safety conscious, professional and obliging in the midst of a complicated job,” explains Mr. 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.”