Reuse of structural steel components from decommissioned offshore structures

Abstract

This thesis presents the theoretical foundation for reusing steel from decommissioned offshore structures in onshore construction projects as a green alternative to new production steel. This would open up a new source of materials in the supply chain of steel components, and contribute to a reduction in the demand of new production steel. Although the conditions and circumstances are different, reuse of offshore steel carry many similarities with onshore steel reuse. This thesis utilizes and modifies already existing guidelines for onshore reuse to determine the feasibility. Included in the feasibility study is one of the most deciding factors of the offshore reuse method, which is the quality check. The thesis proposes a quality check procedure which is based on current guidelines for standards on inspection, testing, and technical delivery conditions. The theory presented in this thesis is put to the test in a case study, where the result indicate that despite significant environmental benefits, reused offshore steel is not yet a viable option in procurement of materials in the onshore construction industry. The feasibility study reveals a reusability index of 51,5%, which is lower than what would constitute a viable reuse operation. However, the reusability index is predicted to increase if the reuse operation is centralized and streamlined by the decommissioning companies.