Booming offshore windfarm projects and increases in fish farm capacity are spurring demand for access systems, writes ABS’ global offshore director and market sector lead for OSVs Dr Wei Huang
Walk-to-work technology, designed to enable crew and service personnel to move safely between vessels and offshore facilities, is finding new offshore applications.
As development of traditional offshore energy projects evolves into increased demand for renewable energy, the booming offshore windfarm market presents a new opportunity for a safe, flexible and proven means of transferring service personnel.
At the same time, the demand for marine proteins leading to expanding offshore fish farm capacity, particularly in Norway, Scotland, Chile, China and across Asia, is also creating a new market for offshore access gangways.
The construction and maintenance of offshore windfarms calls for a combination of expertise that is comparatively new to the US and Asian markets and requires specialist support tonnage. These include jack-up construction units, survey vessels, service operation vessels, cable laying ships and crew transport craft.
Once in operation, the need for regular maintenance means vessels must safely transfer industrial personnel in often adverse weather conditions. In a fish farm application, worker access may also be in multiple locations and challenging conditions.
Walk-to-work technology started as a safety feature on offshore production platforms to improve on the existing means of worker transfer by basket, ladder or helicopter. Walk-to-work systems generally use a telescoping gangway system that offers a higher degree of safety than traditional methods.
These traditional methods of personnel transfer may not be suitable in all cases due to operational requirements such as limited space, the often severe offshore environmental conditions, and operational costs. The gangway system (which employs a motion-compensation system to keep the gangway in a fixed position relative to the turbine or platform) provides safer crew transfer, can operate in almost any weather conditions and is able to cope with high waves.
Gangway systems require specific safety measures to be taken into account when seeking class approval. A Register for Offshore Access Gangways must be maintained on board, containing all pertinent technical data concerning design, maintenance and certification of the gangway.
The motion-compensation system appraisal for compliance covers both passive and active motion systems. For an active motion-compensation system, safety requirements focus on the adequacy of redundancy design, motion sensing and monitoring, and sufficient structural strength.
A risk assessment of the gangway operation is also submitted for approval. This considers the complexity of the gangway systems (especially for active motion-compensated offshore access gangways) in each phase of operation through a failure mode effects and criticality analysis. This verifies appropriate consideration has been given to critical component failure and sufficient redundancy is available where components are not failsafe.
ABS has carried out several recent approvals for gangway installations from the three main original equipment manufacturers, which were assessed in accordance with the ABS Guide for Building and Classing Offshore Access Gangways.