Further to my last post where I made some assertions about the frequency of some failure consequences, there is particularly useful information available from European incident data. EGIG is the European Gas pipeline Incident Group and as the name suggests they collect and report on pipeline failure incidents. A new report is published every three years, available here.
They include information on ignition probability, which is very much less than 100%. The latest report (2011) gives the following probabilities:
- 4% – pinhole/crack
- 2% – hole
- 10% – rupture, < DN 400
- 33% – rupture, ≥ DN 400
So for most Australian pipelines, even full bore rupture has only 10% probability of ignition.