Development of Risk Assessment Code Supplements for the UK Pipeline Codes IGE/TD/1 and PD 8010

The United Kingdom Onshore Pipeline Operators Association (UKOPA) was formed by UK pipeline operators to provide a common forum for representing pipeline operators interests in the safe management of pipelines. This includes ensuring that UK pipeline codes include best practice, and that there is a common view in terms of compliance with these codes. Major hazard cross country pipelines are laid on 3rd party land, and in general have an operational life typically greater than 50 years. The land use in the vicinity of any pipeline will change with time, and buildings will be constructed adjacent to the pipeline route. This can result in population density and proximity infringements, and the pipeline becoming non-compliant with the code. Accordingly, a land use planning system is applied so that the safety of, and risk to, developments in the vicinity of major hazard pipelines are assessed at the planning stage. In the UK, the Health & Safety Executive (HSE) are statutory consultees to this process, and they set a quantitative risk-based consultation zone around major hazard pipelines, where the risks to people and developments must be assessed. Quantitative risk assessment (QRA) requires expertise, and the results obtained are dependent upon consequence and failure models, input data, assumptions and criteria. UKOPA has worked to obtain cross-stakeholder agreement on how QRA is applied to land use planning assessments. A major part of the strategy to achieve this was the development of supplements for the UK design codes IGE/TD/1 and PD 8010, to provide authoritative and accepted guidance on the risk analysis of: i) Site specific pipeline details, for example increased wall thickness, pipeline protection (such as slabbing), depth of cover, damage type and failure mode, and ii) The impact of mitigation measures which could be applied as part of the development. The availability of this codified advice would ensure a standard and consistent approach, and reduce the potential for disagreement between stakeholders on the acceptability of proposed developments. This paper describes the guidance given in these code supplements in relation to consequence modelling, prediction of failure frequency, application of risk criteria, implementation of risk mitigation and summaries the assessment example provided.