Process Safety

[escveritas]

Defining process safety

The most commonly accepted definition of a process safety is from the Centre for Chemical Process Safety (CCPS). The CCPS define process safety as 'a disciplined framework for managing the integrity of hazardous operating systems and processes by applying good design principles engineering and operating practices. It deals with the prevention and control of incidents that have the potential to release hazardous materials or energy. Such incidents can cause toxic effects, fire or explosion and could ultimately result in serious injuries, property damage, lost production and environmental impact.'1. Dissecting this definition, it is important to note that process safety is about a disciplined framework, with a focus on prevention and control of incidents. This can apply to both actual and potential consequence, or 'near misses'. Another important inclusion in the definition is the extension from potential for release of hazardous materials to also include energy. This brings in an aspect beyond just a loss of containment, recognising that a loss of control of energy can also produce catastrophic consequences.

This article also avoids using the terminology Process Safety Management or PSM, because this has a specific legal definition in some jurisdictions, and the management of process safety is not limited to that legal definition.

It is important to recognise that the management of process safety must extend beyond the management of high inventories only. While high inventories pose a potential risk, lower inventories in sensitive areas may also pose such a risk. Expanding the understanding and focus of the
management of process safety to encompass other aspects will assist in recognising and eventually minimising societal risk.

Incidents and events

A process safety event can be defined as follows, 'an unplanned or uncontrolled LOPC of any material including non-toxic and non-flammable materials (e.g. steam, hot condensate, nitrogen, compressed CO2 or compressed air) from a process, or an undesired event or condition that, under slightly different circumstances, could have resulted in a LOPC of a material.'2 While API RP 754 limits this to a focus on loss of primary containment, applying the broader definition of process safety, above, from the CCPS, it should also include release of energy. In simpler terms, this can be expressed as a requirement for a safety system to have a demand on it, regardless of control effectiveness.

An incident is an event where an actual consequence is realised. This may be an actual loss of control, such as a leak or fire. API RP 754 utilises a tiered ranking, to differentiate consequences. At any facility, there are many more instances of potential consequences rather than actual consequences. Acknowledging and analysing these provides for an opportunity to learn from the near miss, rather than have the consequence realised at some future time.