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Challenging the Sea

Challenge – Complete pipe laying system

One of the leading global contractors specialises in seabed-to-surface engineering, construction and services to the offshore energy industry worldwide. To match the evolving needs of deep-water subsea developments, Subsea 7 promises to set a new benchmark in the subsea world with the state-of-art strategic enabler – Seven Borealis, DP pipe lay and Heavy Lift Construction Vessel.

One major feature of the 182.2m long Swiss Army knife is the deep-water S-lay capability. Flexibility and productivity was key.

From the port, single joint pipe sections were fed into the firing line running along the length of the vessel to be welded into a continuous pipeline. After the firing line, the pipeline passed over the vessels stinger at the stem and was lowered to the seabed in an S-shaped curve.

A crane system was required in the length of the S-lay system to ensure flexibility in the operations. Other than pipe transfer, part of the operations needed a lifting system to configure the firing line with eleven stations to make up single joints of pipe, or six double joint stations, offering broad flexibility in the types of pipelines the vessel could install.

The challenges to be solved were the very limited space onboard, the environmental factors and the ever-inconsistent seas. Here is where our partner recommended Jenmon to assist our client.

Solution – Offshore customization

Complex applications required special expertise and solutions. Jenmon was chosen as the provider of Seven Borealis’s 18 units of 10 ton wire rope hoists and 15 ton chain hoists, comprising of under slung cranes and monorail cranes. Jenmn was able to work with the upper management to design cranes that fit their needs.

When designing cranes in ships, it all boils down to the effectiveness of utilising the confined space. With state-of-the-art, high quality products, Jenmon provided special designs with low headroom and an optimised hook approach.

Mounted directly on the ceiling, the underslung cranes and monorail cranes allow efficient material handling even in the tight spaces of the ship. With the energy chain power supply system replacing the traditional festoon systems, work space under the cranes are further increased. This translates into more effective usage of workspace height.

Furthermore, offshore customisation was integrated into the equipment to lengthen the maximum life span and maintain efficiency in the seas.

Meticulous in every gap
Sagging and hogging were common in ships. In order to counter these issues, runways were installed with 50mm apart from each other. Larger wheels of the crane trolley were machined as well. A high demand in precision and quality control were necessary.

Travelling Steadily
Maintaining a steady movement is vital as well. Having to operate this lifting equipment in the middle of the ocean, customised Rack and Pinion drive system was incorporated into the crane track to suit sea-worthiness.

Preventing Corrosion
Taking into consideration the environment, the crane structures were treated in accordance to the specifications in offshore coating systems. Prior to painting, blasting had to be done by using shots to remove all contaminants effectively. For final protection against corrosion, special marine paint was used to provide long-lasting coating. Similarly, the hoist and its components were surface treated and painted with maritime paint.

Results – DNV Tested and Satisfied Customer

In 2011, the hoists and cranes were load tested and certified according to DNV standards in Sembawang Shipyard, Singapore. Our client was very pleased with the results and appreciated Jenmon for the sales and support team.

Jenmon cranes provide assuring reliability and capability, which will enable us to meet our client’s strategic needs, particularly in harsh environment acreage.

Having successfully completed this part of the project, the barge moved off for its next phase of construction. The new flagship vessel will certainly tackle operations on any subsea installation project worldwide.