Week 6 (LOPA)

Question 1

what is the main use of LOPA?

Answer 1

LOPA is about barriers in order to mitigate or prevent hazardous events.

Question 2

LOPA structure (what is the order of the different assessment criteria LOPA uses)

Answer 2

The cause
The consequence
Target mitigating likelyhood
Independent Protection Layers

Question 3

what are examples of Independent protection layers (IPL’s)

Answer 3

Control loops / Alarms / Pressure relief valves / Trips / Bursting disc / Bunds

Question 4

What is a recommendation in a LOPA form?

Answer 4

A recommendation is adding an IPL to a process (cannot be more)

Question 5

How is Safety integrity level measured?

Answer 5

SIL 1) 0.1
SIL 2) 0.01
SIL 3) 0.001
SIL 4) 0.0001

Question 6

What are advantages of LOPA?

Answer 6

Simple and quick
Gives quantitative value
Method of identifying IPL’s

Question 7

What does BPCS stand for and what are examples of it/

Answer 7

Nasoc process control system loops = alarms/trips

Question 8

What is an initiating cause (and whats its’ frequency)?

Answer 8

The failure of a BPCS loop.
Depends on the question normally 1.

Question 9

What is the time at risk?

Answer 9

If there is a continuos process - it is how many workers are at risk as its running throughout the year.
If not continuos calculate how many workers are at risk per year.

Question 10

What is TMEL?

Answer 10

Target mitigating event likelyhood - how much level of risk will you accept. (10-7 normally)