This International Standard specifies the functional requirements and principles for design, operation and requalification of pipelines in the petroleum and natural gas industries using reliability-based limit state methods as permitted by ISO 13623. Reliability-based limit state methods provide a systematic way to predict pipeline safety in design and operation. This International Standard supplements ISO 13623 and can be used in cases where ISO 13623 does not provide specific guidance and where limit states methods can be applied, such as, but not limited to, ? qualification of new concepts, e.g. when new technology is applied or for design scenarios where industry experience is limited, ? re-qualification of the pipeline due to a changed design basis, such as service-life extension, which can include reduced uncertainties due to improved integrity monitoring and operational experience, ? collapse under external pressure in deep water, ? extreme loads, such as seismic loads (e.g. at a fault crossing), ice loads (e.g. by impact from ice keels), ? situations where strain-based criteria can be appropriate. This document applies to rigid metallic pipelines on-land and offshore used in the petroleum and natural gas industries.