I like LOPA as well as the next person; I'm one of the two co-originators as you likely know. But all of the quantitative methods use "statistical" values (but not as statistical as most think) that have in fact been "voted" upon by "experts", so you can either let LOPA or QRA analyst use factors [...]
The main benefit to a business (set aside any "government regulator" issues for now, since that should not be very important) in implementing SIS standards is the consistency in understanding the safeguard level for an instrumented safety system. But, there are disadvantages to following "only" IEC 61508/61511. One disadvantage is that the PFDavg calculated for [...]
Since I'm one of the two originators of LOPA in 1995 and one of the two primary authors of the CCPS books on LOPA (2001 and 2012), I (and many others) believe we are doing Too Many analysis. A well-structured and well led PHA team does 95% of the risk analysis and 99% of the [...]
Double-jeopardy is NOT a discussion of (or failure of) multiple layers of protection. Nearly every scenario should have multiple layers of protection against the ultimate (unmitigated) consequence. Double jeopardy is also NOT a deviation combined with failure of a safeguard that then "lies in wait." Double jeopardy is the occurrence of two deviations or two [...]
Trouble-Shooting guides is the term many folks use to for the list of steps and decisions necessary to tale when a deviation from the normal opertion occurs. It is what an operator does to prevent a deviation from leading to an emergency shutdown or worse. (Trouble-Shooting guides are significant extensions of waht some call Operating [...]
