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Requirements for high strength structural steels

Since 2014, the Petroleum Safety Authority Norway and HSE UK have cooperated in a forum with the class societies DNV GL, Lloyds Register and ABS on requirements for high strength structural steels. A special publication summarises some of the work.

"Position paper - Material property requirements for high strength steels used in mobile offshore units" summarises some of the work undertaken and has been written in partnership with HSE UK.

Challenges - high strength steel
There have been certain incidents and difficulties involving high strength steel due to its lack of ductility or deficient requirements for testing its fracture toughness. This latter may lead to an inadequate documentary basis for a fracture mechanical evaluation of technical integrity in the operational phase or in connection with a wish to extend a facility's lifetime or presence on the field.

The objective of the work was to identify weaknesses in existing requirements and rules for mobile facilities in respect of high strength steels, and thereby contribute to potential improvements.

Requirements, experiences and proposed improvements
The document briefly presents HSE UK's and the PSA's requirements for mobile and fixed facilities in respect of high strength steels, certain structural experiences, incidents and proposed improvements.

The work has contributed to implementation of requirements for fracture mechanics testing in International Association of Class Societies (IACS) UR W16. These are the class societies' mutually agreed requirements. The change here covers weldments' heat-affected zones as part of the steel mill's qualification criteria.

The work in the forum has also contributed to clarification and discussion of other potential safety challenges in the use of high strength structural steels.

For the PSA, the work was linked to our sectoral focus on the integrity of ageing structures and marine systems. The PSA would like to thank HSE and the ABS, Lloyds and DNV GL class societies for a productive cooperation.