To calculate the risks associated with major accident hazard pipelines in the UK a computer code, MISHAP01 (Model for the estimation of Individual and Societal risk from HAzards of Pipelines), is used. The aim was to rewrite MISHAP01 and PipelineRiskAT within a single program to facilitate the implementation of future improvements to the model.
This report summarises all three aspects of the model updates (solution method, science changes
and data updates) and provides an overview of the results obtained compared to the original
version of PIPIN.
The objectives of this project were to investigate the impact on the calculated failure rates as a
result of changes to the data within PIPIN. These changes were required to ensure that the input
data was representative of UK pipelines by ensuring that all of the latest available information
was being used.
The aims of this project were to investigate the impact on the calculated failure rates as a
result of changes to the science within PIPIN. The changes had been suggested after the model
was independently reviewed.
HSE uses a fracture mechanics model, PIPIN (PIPeline INtegrity model), to predict the likelihood of failure if a buried pipeline is struck by machinery. The existing model fails to produce results for some scenarios. The Health and Safety Laboratory were asked to rewrite PIPIN replacing the methodology with a Monte Carlo solution method.
HSE uses a model, MCPIPIN (Monte Carlo PIPeline INtegrity), to determine failure frequencies for major hazard pipelines. It uses two models; one based on operational experience data and a predictive model. The historical failure rates used in the operational model are over 10 years old. A review took place to update this data.
RR1034 – Review of the event tree structure and ignition probabilities used in HSE’s pipeline risk assessment code MISHAP
HSE uses the MISHAP (Model for the estimation of Individual and Societal risk from HAzards of Pipelines) model to calculate risks associated with major hazard pipelines in GB. The review took place in response to the UK Onshore Pipeline Operators Association (UKOPA) challenging some of the assumptions and methods currently used within the tool.
RR1072 – Investigations into the immediate and underlying causes of failures of offshore riser emergency shutdown valves
Riser emergency shutdown valve (RESDV) failures, whether arising from a test or a real demand, are reportable to HSE under RIDDOR and a preliminary survey found approximately 180 cases of failure. Given the criticality of RESDVs to offshore safety, it was determined that the reasons for these occurrences should be investigated.
One of the UKs biggest gas distributers was sentenced today after admitting safety failings in relation to the death of a young boy.