This document describes processes for managing major accident (MA) hazards during the design of offshore oil and gas production installations. It provides requirements and guidance on the development of strategies both to prevent the occurrence of MAs and to limit the possible consequences. It also contains some requirements and guidance on managing MA hazards in operation. This document is applicable to the design of — fixed offshore structures, and — floating systems for production, storage and offloading for the petroleum and natural gas industries. The scope includes all credible MA hazards with the potential to have a material effect on people, the environment and assets. This document is intended for the larger projects undertaken to develop new offshore installations. However, the principles are also applicable to small or simple projects or design changes to existing facilities and can also be relevant to onshore production facilities. Mobile offshore units as defined in this document are excluded, although many of the principles can be used as guidance. The design of subsea facilities are also excluded, though the effects of mobile and subsea facilities are considered if they can lead to major accidents that affect an offshore installation. This document does not cover the construction, commissioning, abandonment or security risks associated with offshore installations. The decision to apply the requirements and guidance of this document, in full or in part, is intended to be based on an assessment of the likelihood and possible consequences of MA hazards.