Report on a Second Study of Pipeline Accidents Using the Health and Safety Executive's Risk Assessment Programs Mishap and Pipers

In an earlier work "Health and Safety Executive [HSE] Contract Research Report 294/2000", international literature describing accidents involving major failures of pipelines was studied and comparisons were made between the accident consequences observed and those calculated using the HSE risk assessment program MISHAP98 and its continuing development version PIPERS.

The study focused primarily on MISHAP98 and accidents involving pipelines carrying natural gas.

Such pipelines are especially important to the work of HSE because there are in the UK about 20,000 km of transmission pipelines carrying natural gas at high pressure.

It was found that for such pipelines the fireball model in MISHAP98 generally over-predicts the consequences of rupture, whilst the jet-fire model invariably under-predicts the consequences.

Main recommendations of the study were that the jet-fire model should be improved, and that a larger set of pipeline incident reports, known to be available in the USA and Canada, should be obtained and studied in a similar fashion.