Week 6 Flashcards
Examples of ISD?
Replace a large batch reactor with a smaller continuous reactor.
Reduce storage inventory of raw materials
Use chemicals with higher flash point temperatures, boiling points, and other less
hazardous properties.
Use solvents that are less hazardous, for example using water and detergent
instead of ethanol which is flammable for cleaning greasy parts
Reduce process temperatures and pressure.
Provide barriers to reduce impacts of explosions.
Reduce piping lengths, valves, and fittings.
Select equipment that requires less maintenance.
Methods of implementing ISD
Simplify, minimise, substitute & moderate
Hierarchy of controls
Elimination, Substitution, engineering controls, administrative controls, PPE
Mistakes of Hierarchy control
1- Being Reactive Rather Than Proactive:
2- Starting at the Bottom of the Hierarchy:
3- Always Using the Cheap Fix
4- Applying a Control and Forgetting About It:
5- Too Much Emphasis on Training
8 Layers of LOPA
Layer 1: Process Design (e.g. inherently
safer designs to reduce hazards);
Layer 2: Basic controls, process alarms,
and operator supervision;
Layer 3: Critical alarms, operator
supervision, and manual intervention;
Layer 4: Automatic action (e.g. Safety Instrumentation System (SIS*) or Emergency Shut Down (ESD**));
Layer 5: Physical protection (e.g. relief devices);
Layer 6: Physical protection (e.g. dikes);
Layer 7: Plant emergency response;
Layer 8: Community emergency response (not shown in the figure)
LOPA terminology
Layers of protective analysis; semi-qualitive
Layers of protection THE METHOD (5)
- no single method of mitigation will be used around a significant hazards system
- several methods will be utilised to provide “safety redundancy”
- the greater the risk/consequence the more the levels of protection will be there
- initial layers lower the risk of an incident occurring
- outer layers mitigate the consequences of an incident
When is ISD most impactful
At the early stages eg. Design stage
Types of hazards used for ISD
Process hazards, reaction hazards, operating hazards, inherent hazards with chemicals used
Where to use ISD
Conceptual design, selection of technology, selection of locations
Safety management of processes should be done at both
- Individual hazard level
- Whole system level
Disadvantages of PPE
Need to wear the right equipment for the hazard.
Needs to be fitted to the individual worker.
Training in use is necessary.
Understand equipment limitations is essential.
Not often worn when it should be.
IPL terminology
Independent protection layer
LOPA
A method to capture the main concepts of independent, protective safety systems, without requiring a high degree of quantitative analysis
It is used to understand how a process deviation can lead to a hazardous consequence, if not interrupted by the successful operation of a safeguard called independent protection layer
IPL
is a safeguard that can prevent a scenario from propagating to a consequence of concern without being adversely affected by either the initiating event, or by the action, brackets, or in action) of any other protection later, in the same scenario
