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Ebook: Inherent Safety



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Ebook: Inherent Safety

Overview

The term 'Safety' as used in the process industries can be divided into three major categories:  


Inherent (the topic of this ebook);
Process Safety
  Passive
  Active
  Procedural
Occupational/Personal


Of these three the most effective is Inherent Safety — the topic of this ebook. The basic idea behind the Inherent Safety concept is simple; process facilities should be built such that, were there to be any type of failure, the system would reach a safe state regardless of the existence and effectiveness of safeguards.

 Inherent Safety can be achieved in one of three ways:
 
1.   Remove the hazard;
2.   Ensure that the consequences of an event have no significant impact;
3.   Remove people from the location so that no one can be injured no matter how serious the event.

The next type of safety in the above list is Process Safety. There are various types of Process Safety — one of which is Passive Safety. A passive safety system is one that brings an out-of-control condition back to a safe state without any action required from equipment, instruments or facility personnel. An example of a passive safeguard is to do with the containment (bund) walls that are typically located around storage tanks, as shown in Figure 1.

 

Figure 1
Bund Wall

Ebook: Inherent Safety

 

The volume of the bund is usually 110% of the volume of the tank. Thus, if the tank fails catastrophically, the spilled liquid will be contained. The wall is totally passive, requiring neither equipment nor human intervention in order to be effective. It will always be there, regardless of what else is going on. 

It can be seen that passive safety and inherent safety have a lot in common. However they are not the same. The bund wall in Figure 1 is not truly inherently safe. For example the wall has a drain valve, as shown. The valve is opened to drain off accumulated rain water. If the valve is inadvertently left open then the passive safety system has been defeated.

 

The third item on the above list is Occupational Safety. This includes issues such as PPE (personal protective equipment) and basic training in safe operations. Although many occupational safety programs are developed to respond to failures in inherent and process safety the principles of Inherent Safety can still be applied, as discussed later in this ebook.

Contents

Introduction
Examples of Inherent Safety
Features of Inherent Safety
  Inherent to Design
  Way of Thinking
  Safety Independent of Response
  Can Help Reduce Costs
Eliminate
  Remove Equipment
  Remove People
  Stop an Activity
Minimize
Substitute
Moderate
  Equipment Modification
  Reliability
  Spacing
  Underground Location
Simplify
Timing and Personnel
Occupational Safety
Unintended Consequences
  Eliminate
  Minimize
  Substitute
  Moderate
  Simplify
Reference Material

Other Materials

We provide a video to do with Inherent Safety in the process and energy industries.

 
At our Process Risk and Reliability Management blog site we provide discussion and updates to do with Inherent Safety.

Purchasing Information

This video comes as part of a package; it includes:

  • The video
  • The ebook
  • The storyboard to go with the video
  • A test

This package can be downloaded here.

About the Author

Ebook: Inherent Safety

Ian Sutton is a chemical engineer with over 40 years experience in the process industries. He has worked on the design and operation of offshore platforms, refineries, chemical plants, pipelines and minerals processing facilities.



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