In response to recent research and development work and the industry’s operational experiences with mooring systems, DNV has now released a complete set of Offshore Standards covering systems design, materials, product quality, certification requirements and the fabrication process.

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Astrid Gaarde, head of DNV’s mooring section

Several recent mooring incidents have jolted operators of offshore installations into finding ways to ensure that mooring systems meet acceptable safety requirements. DNV’s new set of Offshore Standards helps industry players to demonstrate their commitment to safety.

Wealth of experience
The new set of standards comprises
o DNV-OS-E301 Position Mooring (issued October 2008), update of previous revision
o DNV-OS-E302 Offshore Mooring Chain (issued October 2008), new standard
o DNV-OS-E303 Offshore Mooring Fibre Ropes (issued April 2008), new standard
o DNV-OS-E304 Offshore Mooring Steel Wire Rope (to be issued April 2009), new standard

The standards take into consideration the wealth of experience in mooring chains that has been gained by the industry over the past few years. Advances in materials and testing that have helped to improve product quality are included in the standards.

“We worked particularly hard to ensure that a more appropriate regime is put in place when it comes to fabricating and testing shackles and components in mooring systems. This will help the industry to overcome challenges involving brittle materials,” says Astri Gaarde, head of DNV’s mooring section.

The new standards are aligned with the DNV certification scheme for mooring systems which again is in compliance with current requirements set out by the International Association of Classification Societies.

Challenging environmental conditions
Further, moorings in various locations around the globe experience many different combinations of wind, wave and current effects. The specification of metocean conditions for mooring design has been improved to better cover this variety, and more examples have been provided for guidance to operators in international waters. The Gulf of Mexico has been covered specifically in the aftermath of recent hurricanes, as has West Africa following squall conditions there.

Industry participation
As a result of the recent mooring incidents, authorities and regulators have focused to an increased extent on following up mooring systems’ design and operation. During the development of the new standards, DNV has been in close dialogue with all interested parties and each standard has been subject to a quite extensive industry consultation process, with all the relevant comments being incorporated into the final revision of the standards.