Layer of Protection Analysis (LOPA) is an analytical procedure which uses the outputs from Hazard Identification methods such as Hazard and Operability Study to quantitatively estimate the frequency/likelihood of an identified consequence occurring. The occurrence of the consequence is assessed and a ‘tolerable’ frequency target is assigned. The more severe the identified consequence is, the lower the target frequency needs to be. The technique takes account of the effect of the initiating events which could be control system or equipment failure or human error all the way through ‘modifiers’ such as time at risk, probability of ignition and explosion, to protective barriers such as alarms and trips. The outcome indicates if the target tolerable frequency is achieved and if not, what further risk reduction is required. This may result in the deployment of Safety Instrument Systems. LOPA is one of the most popular risk assessment methods described in the International Electrotechnical Commission standard IEC 61511.
Course Level: Skill / Advanced Instructor: Richard Gowland
Designed for you, if you are...
A production engineer
A process control engineer
An instrumentation system designer
A process safety engineer
How we build your confidence
This comprehensive course gives a complete description of the method from assigning tolerable target frequencies in line with company and regulator requirements through all steps of the method. In many cases LOPA discovers gaps in protection or cases of common cause failure. When these occur, risk reduction measures such as Safety Instrumented Systems (SIS) need to be incorporated into the operating system.
The provided course materials include a manual in paper and electronic form and the necessary software for carrying out LOPA studies.
The benefits from attending
The course aims to provide you with the ability to conduct the LOPA study and to train others using the provided material including study software.
The whole LOPA method
Setting the target tolerable frequency for defined scenarios and consequences
Identifying initiating events and assigning event frequencies
Accounting for enabling factors such as time at risk
Accounting for ‘conditional modifiers’ such as probability of ignition, weather conditions
Accounting for any alarms or safety trips incorporated in the normal process control system
Accounting for other safety related protection systems such as pressure safety valves
Accounting for any Safety Instrumented Systems existing or added as part of the study
Analysing the outcome for sensitivity and uncertainty
Assessing if the outcome is in the range of tolerability - using a cost/benefit assessment for further risk reduction (the ALARP principle)
Fitting the LOPA process into a Process Safety Management System
Audit and Inspection and regulatory authority expectations