Geohazards and Weather-Related Outside Force The threat category ‘Outside Force’ in a risk assessment typically includes forces such as ground/earth movement, flooding, cold weather, and lightning. When buried pipelines cross sloping terrain, there is a danger that soil movement (down the slope) will impose an excessive load on the pipe that could lead to failure. […]
Results for time dependent failure mechanism
Ok, so how do I convert from TTF to PoF?
This is one of the more challenging aspects of modern risk assessment. One of the keys is to select the future date for which the PoF is being estimated. This is often ‘next year’ but can really be 5 years, 10 years, 20 years, etc into the future. Another key is to ensure that both likely and […]
Why do I need a PoF for time-dependent failure mechanisms? The TTF is more relevant since it drives integrity re-assessment schedules and other risk mgmt. efforts.
TTF is indeed the more useful metric for many applications. However, the TTF has a probabilistic aspect that must be understood before its use in, for example, setting an integrity reassessment interval. The TTF calculation uses segment lengths since degradation mechanisms are usually related to surface areas. A probabilistic TTF per mile is an intermediate calculation […]