Allseas’ “Pioneering Spirit,” the world’s largest and most versatile offshore vessel, installs and removes the heaviest offshore platforms in a single lift. Sixteen motion-compensated lifting beams, mounted on the vessel’s bows, can lift and support entire platform topsides weighing up to 48,000 tons – even in rough seas. At the heart of these lifting beams are Schaeffler spherical plain bearings, which operate under extreme loads to absorb and compensate for complex forces.

To maximize their service life and ensure rapid availability, Allseas opted to have the maintenance-free bearings remanufactured rather than replaced. This approach avoids the long lead times associated with purchasing new bearings and undergoing Lloyd’s Register testing procedures.

From the challenge to the removal and remanufacturing of the bearings – this is how the process unfolded.

Challenge

Installing or removing oil platforms at sea is a complex process that often requires the use of special ships and technology. “Pioneering Spirit” is one of a kind. Measuring 382 meters in length and 124 meters in width, the split-bow vessel glides across the water with remarkable stability. Once on site, she installs or removes entire topsides or steel substructures – known as jackets – using specialized lifting systems tailored to each operation.

Preparation is the key

Depending on the specific conditions and requirements of the respective platform and region, the time required to construct or remove offshore platforms can range from 18 months to several years. Roughly speaking, the planning can be divided into four phases: preparation, mobilization, removal and follow-up. Preparation takes a lot of time. This includes, among other things, the feasibility study, environmental impact assessment, regulatory approvals, inspections and assessments, technical plans and a detailed safety plan. This is the only way to ensure that the complex process of installing or removing an offshore oil platform is carried out safely and efficiently.

Back-breaking work for lever arms & spherical plain bearings

Moving topsides is a feat of strength in which the 16 lifting levers have to withstand high loads and enormous forces. Once the vessel is positioned around the platform, the lifting beams are aligned with pre-installed lifting points on the underside of the topsides. Once everything is secured, tension in slowly built up, and the lever accumulates power to deliver the „fast lift“, a vertical upwards stroke that lifts the topsides 4 meters in just seconds. The spherical bearings in the lifting levers play an important role here. They are used to combine mobility and load-bearing capacity. They also help to safely support the complex movements and loads that occur when lifting and lowering heavy objects. The bearings are not only subjected to high loads, but also to different strengths. This takes a toll. Although these are maintenance-free spherical bearings, they also need to be regularly inspected to ensure that they are working effectively.

How to deal with signs of wear? That’s what Allseas says:

“When we determine that a bearing shows signs of wear or damage, we have to decide whether the bearing can be saved – whether there are alternatives to a new purchase. It’s not primarily a financial issue that drives us to address this question, but rather a time issue. The duration of sourcing new materials for parts certified to Lloyd’s Register rules and regulations can take several months. This is a good reason to consider reusing the parts that are within tolerances. Having the original warranty and certification after a controlled refurbishment programme is a benefit, especially if this can be achieved within a tight time frame.”

A maintenance employee at Allseas

Solution

Allseas decided to have the damaged bearings remanufactured for two reasons. Firstly, this allowed the full operating life of the bearings to be utilised, and secondly, the spherical plain bearings could be returned to the installation location much more quickly. Additionally the mounting procedure was updated for better service life of the bearings. This is because the testing and acceptance procedure for remanufactured bearings takes only a short time, ideally 2 days. Turnaround time for inspection and reconditioning (if required) is approximately 30 days.

Starting signal

One call to Schaeffler Netherlands was enough to get the work started. After the joint bearings had been removed and inspected by Schaeffler employees on site, it was clear that remanufacturing the large bearings, which weighed 930 kilograms, was worthwhile. Just a few days after this ‘diagnosis’, it was clear that a further inspection by opening the bearings to assess their condition was the best way forward.

What exactly was done?

In the first step, eight spherical plain bearings were dismounted into their individual parts and cleaned. After cleaning, the experts were able to get a good overview of the next processing steps. All the measures to be taken were outlined on paper and worked through step by step. Additionally the mounting procedure was updated for better service life of the bearings sliding layers, seals, pins and bolts were replaced. Some grinding work and new chrome plating were necessary. Before the bearings were rebuilt under the supervision of the Lloyd’s surveyors, all components were polished. After the bearings were properly repackaged in long-term packaging and returned to the “Pioneering Spirit”, the installation of the bearings – done by the Allseas TLS team – was supervised and approved by Lloyd’s Register.