Topic: Pof from TTF

Note: the following answers are short and direct, sometimes omitting information that might be helpful for full understanding. Please consult your copy of the book or other resources on this site for more complete answers.

ILI vs DA—The Risk View

A rather common issue these days is decision making involving comparisons between In Line Inspection (ILI) vs Direct Assessment (DA, and, in particular, External Corrosion DA or ECDA).  You may need to research these techniques, if not already familiar to you, since we will assume the reader is fairly familiar with both. Both are acceptable […]

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 […]