MoorLink’s chain locker closure device has gained approval from the American Bureau of Shipping (ABS), which accepts it as a solution for making chain lockers weather-tight. It is currently one of very few ABS-approved products for this task, according to its inventor, technical manager Morten Gundersen.
MoorLink’s chain locker closure device is the only ABS-approved product for making chain lockers weather-tight for large chain sizes.
Tests on the patented closure device were carried out by the ABS and the US Coast Guard after it was installed on BP’sThunder Horse semisubmersible production platform. The tests showed that it provided an effective seal against water ingress into the large anchor chain lockers while the chains are deployed.
US approval for the device fills an important gap, as no existing alternative for large chain sizes has been cleared for use in the Gulf of Mexico, although there is a regulatory requirement that the lockers on many units should be weather-tight. Consequently many semisub installations in the GoM have had to operate under an exemption.
MoorLink’s system seals the opening through which the chain exits from the locker. The bottom of the device is bolted onto the flange mounted at the top of the opening. The upper part of the device is suspended on springs and sits on a rubber bellows, which together give it the mobility to center itself around the chain. All the parts come in two halves, so that they can be mounted with the chain in position.
At the top of the device are two pivoting covers, one on either side. Fitted around the rim of each cover is an inflatable seal. The covers are placed in position manually, and the seals are then inflated to form a weather-tight seal round both the chain and the outside of the covers.
The device enhances the platform’s stability, and therefore its safety. An additional benefit is that the chain locker volume can be included in stability calculations, thereby increasing the deck load. The volume can be substantial -Thunder Horse, for example, has 16 such spaces, each measuring 25 m (82 ft) high by 6 m (19.68 ft) in diameter, equivalent to a total of 11,200cu m.
MoorLink recently received an order for this equipment for Exmar’s Opti-Ex production platform which is under construction by Samsung Heavy Industries in Korea, with an optional unit possibly to follow. Hydro has also expressed interest as it prepares for major upgrades on some of its production platforms in the Norwegian sector.
Tether connection
MoorLink’s range of products for drilling rig mooring systems includes ball swivels, connections, and wire clamps. Since starting up 12 years ago, the company has supplied around 500 swivels. It now plans to extend its range to components for floating production installations, taking the approved drilling rig concepts as a basis.
As an engineering company which subcontracts all its manufacturing, MoorLink remains true to its original business idea of developing new products where it sees an opportunity for improvement. For instance, it has developed tether connectors for FPSO moorings. Following initial deliveries to ExxonMobil’s Kizomba A and B projects off Angola, it now has an order from Technip for tether connectors for a Petrobras project in Brazil.
Other products at different stages of the development process include a subsea connector, the M-link polyester rope connector, and the Moorsafe anchor.
The design of the subsea connector, which is intended to be installed on a suction anchor or pile for connection of the anchor chain, has undergone fine tuning following feedback from customers. Its functionality has been improved, says managing director Björn Palmquist. The connector, which is also patented in the US, recently made the final round in the bidding for a major semi project in the GoM.
MoorLink has also applied for a patent for the M-Link, a new product for use with polyester rope. This concept is an improvement on the existing H-Link, resulting in a connector which is easier to install and recover, has a reduced weight, and is more cost-efficient than the traditional connector.
In the Gulf of Mexico, the company is benefiting from hurricane-related upgrades to mobile drilling unit mooring systems. Recently it delivered swivels to 11 Diamond Offshore and five Noble Drilling rigs.
An influx of rigs into the Gulf of Mexico is also helping, according to Palmquist. A forthcoming API mooring guideline with more stringent requirements should also prove beneficial.
The company also has swivel orders for two semisubmersibles working in the Norwegian sector, theTransocean Leader and Odfjell’s Deepsea Delta. In this sector, the chief concern is stricter requirements in the Norwegian Oil Industry Association’s guidelines for safe mooring operations. •
For more information contact Björn Palmquist, MoorLink. Tel +46 31 721 3800, fax +46 31 708 79 00, [email protected], www.moorlink.com
