Methodology to assess pipeline fitness for change of use


The Net Zero Technology Centre (NZTC) has laid out a methodology for assessing the fitness of a pipeline for a change of use.

Publishing the report in early December, the NZTC set out how the UK has over 1,000 oil and gas pipelines, measuring 45,000 kilometres in length, which could potentially be repurposed to transport hydrogen and CO2. However, doing so successfully will call for an accepted methodology to be established, one that can assess the suitability of a particular pipeline for the change of use and a life extension.

The approach it propose is one that considers the pipeline having the potential to be an asset for many years, and one that can be used for a variety of purposes, with changes in fluid, temperatures and pressures all envisaged. At the core of its methodology is a technical integrity assessment carried out in two-parts, the first being a review of the period from design until the present day to determine the current condition of the pipeline, with the second then looking to determine where the end of life may occur.

It highlighted how a critical element of this assessment is the modelling of degradation and the probability of failure. It acknowledged how some of the modelling tools implicit in this approach may not yet be fully developed, so could require further work. It further stressed that technical integrity cannot in isolation and should be seen in the context of a suitable and operational Pipeline Integrity Management System, a managed system of safety-related equipment, and a licence to operate based upon legal compliance and social acceptance.

Its methodology, therefore, proposes six steps to assess the suitability of a pipeline for being repurposed to transport a different fluid, which would also result in an extension to the required life of the pipeline. The first is defining the boundaries of the particular pipeline system and assessment, where all existing data and documentation from the initial design calculations should be reviewed through to the latest available reports to get a clear picture of how the pipe was designed, installed, commissioned, operated, inspected and modified.

Next steps would then involve reviewing the existing Pipeline Integrity Management System and performing a gap analysis to determine what needs to be improved, or introduced, to accommodate future business opportunities; carrying out a performance review of associated safety-related equipment; and conducting a legal compliance review to ensure that the proposed methodology complies with legal requirements, before then using the outcomes from the initial steps as input into a risk assessment to determine the most likely current integrity condition of the pipeline.

Following on from this, it recommends the risk assessment is extended to look forward to determine potential changes in integrity status in future, in relation to different fluids and new business opportunities.