Extreme environmental loading of fixed offshore structures

HSE initiated a study in May 2018 to develop guidance on the assessment of structural failure from extreme environmental loading on fixed offshore platforms. Recent advances in both metocean statistics, and the physical understanding of extreme wave events, have demonstrated that commonly applied methods of assessment can be non-conservative and that wave impact on the deck needs to be accounted for.

The key objectives of the study were to:

The work was undertaken by the Offshore Consulting Group (OCG) and the scope included participation in the LOADS joint industry project, which is a leading industry effort to develop guidance on the 10,000-year event for incorporation into relevant offshore standards, such as the ISO 19900 series.

The scope of work entailed the following components:

Thirteen reports providing recommendations on the assessment of extreme environmental loading of fixed structures are available. These are:

Summaries of the two components of the study are presented in the reports Extreme Environmental Loading of Fixed Offshore Structures: Summary Report, Component 1  and Extreme Environmental Loading of Fixed Offshore Structures: Summary Report, Component 2. Recommendations on the methodology for the assessment of extreme loading based on the findings of the study are provided in the document Extreme Environmental Loading of Fixed Offshore Structures: Guidance .

The study made the following conclusions:

The high-level findings from the study are being incorporated into ISO 19901-1 which is currently being revised.

A risk-ranking of all UKCS fixed platforms for the inundation of the topsides and safety critical equipment at a 10,000-year return period, based on a consistent estimate of extreme total water elevation (the sum of crest, surge and tide) and which included effects beyond second-order and wave breaking, indicated the following:

The results indicate that there is a need to reassess fixed structures for extreme environmental loading using the procedure defined in the study, but it is also recognised that the application of the advanced techniques involved is not straightforward and requires both a further stage of development, including wider validation and calibration of the procedures, and training on their implementation. 

To facilitate this, an offshore industry network on the environmental loading of offshore structures, the Metocean Network, was launched on 30 September 2020 with the support of the Energy Institute and it will convene at regular intervals. The network made a very strong start with a large number of participants from the UK, Europe, North America and Australia. The aims of the Metocean Network are to:

The creation of the Metocean Network will promote better understanding of control of the risk of structural failure from extreme wave loading through reliable structural assessment, and the implementation of suitable mitigation strategies, where appropriate, to ensure the safety of the offshore workforce. It is important to note that the network should enable the development of recommendations on the integrity management of both fixed and mobile offshore installations. The network is open to all stakeholders and it is in the interest of all to participate in it. 

Contact

Stakeholders who have not yet joined the Metocean Network are encouraged to contact Dr Cameron Stewart of the Energy Institute to be added to the participants' list: e-mail: [email protected]

For further information on the Extreme Wave Loading Study and the Metocean Network, please contact Dr Alexander Stacey: e-mail: [email protected]

Updated 2021-04-23