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Safety Moment #54: The Process Safety Carousel

The Process Safety Carousel

This post is taken from the corresponding post at the Sutton Technical Books site

One of the challenges to do with process safety management (PSM) is circular reasoning or logic. Many of the PSM elements tend to become self-referential. Process hazards analyses can illustrate this conundrum with discussions on the following lines.

  1. Could high temperature in this vessel lead to a serious incident?
  2. What is high temperature?
  3. It’s that temperature that could cause a serious incident.

Similar difficulties can be seen when deciding on how to manage a proposed change to the facility. This time the question/answer sequence can go as follows.

  1. Does this proposed change require implementation of the Management of Change (MOC) program?
  2. We don’t know — we will have to run it through the MOC system to find out.

The use of risk-based analysis tools can create a related set of problems. For example, many facilities use the concept of ALARP (As Low As Reasonably Practical Risk), say when deciding on whether to use a new material of construction.

But the use of the word “reasonable” in the definition of ALARP requires its own definition, otherwise, once more, a circular discussion is created.

In situations such as these a fundamental problem is that the values being used are qualitative, and often quite subjective — a level of risk that is acceptable to one person may be totally unacceptable to another. There is no right or wrong in situations such as these — merely different opinions.

The only way of breaking the circular logic is to use to use numbers — to move toward quantification. So, for example, it may be decided that “high temperature” is 250C. This means that, if the temperature in the vessel reaches that value, then it action must be taken to reduce the temperature — otherwise there could be a release of flammable or toxic materials from it.

With regard to risk it is much difficult to assign numerical values due to the inherent subjectivity of the topic, as just discussed. Moreover, there is a public relationships aspect to think about. If a manager states that the target value for fatalities is say one in a thousand years, then that manager has said that fatalities, even at a very low level, are acceptable. This is something that he or she probably wishes to avoid doing.

There is no definitive answer to the difficulties just raised. Risk is fundamentally a subjective matter. All that can be said is that, wherever possible, quantitative limits and goals need to be defined.

Chemical Safety Board Changes

Hamlet: Lose the Name of Action

The Chemical Safety Board (CSB) continues to undergo unsettling changes, as described in the C&EN article Changes on tap at U.S. Chemical Safety Board, and in the PEER report Outgoing Chemical Safety Chair Fires Managing Director.

The following is a comment on the C&EN article made by Ian Sutton.

As a process safety professional I have two responses to this article.

The first is that clients reasonably expect to receive reports from incident investigations and hazard analyses promptly. Delays lead to justified frustration for the client, and the sense of urgency and opportunity is lost. In particular, if there has been a serious event at a process facility, senior management is shaken up and is usually willing to spend the money and do whatever it takes to prevent something similar from happening again.
When I read, “six reports were incomplete, one of which stretched back six years”, my mind jumped to Hamlet’s words to do with delay (in his case, procrastination),

. . . enterprises of great pith and moment . . . their currents turn awry, And lose the name of action.

After six years, any sense of urgency is long gone. The “name of action” has disappeared.

The Chemical Safety Board want their investigations to be thorough. But that goal has to be traded against the importance of timeliness.

In the immediate follow-up to a serious incident, site management will often issue “Immediate Temporary Controls (ITC)”  — generally within 24 hours. They don’t know the root causes of the event but that can identify immediate causes.

Let’s say that a leak was caused by corrosion under insulation; the ITC could be to “Check the integrity of all piping under insulation”. Later on, the incident investigators may identify a root cause, say to do with not properly following engineering standards.

Maybe the CSB could do something similar, i.e., issue recommendations very quickly based not on root causes, but on immediate causes.

The second thought is that process safety management (PSM) is now well-established and mature. After all, the first standards were issued in the early 1990s. This means that managers are used to looking at incidents in terms of the elements of PSM such Management of Change, or Operating Procedures, or Prestartup Safety Reviews. It would be helpful if the CSB could organize its analysis and finding around those well-established elements.


Revised BSEE Drilling Rules

BSEE (the Bureau of Safety and Environmental Enforcement) is proposing to roll back some of the offshore safety rules that were promulgated following the Deepwater Horizon/Macondo catastrophe. Specifically, they have published a Revised Well Control Rule for comment. Their justification is,

. . . after thoroughly reexamining the original Blowout Preventer Systems and Well Control final rule (WCR), experiences from the implementation process, and BSEE policy, BSEE proposes to amend, revise, or remove current regulatory provisions that create unnecessary burdens on stakeholders while ensuring safety and environmental protection.

Many reviewers are concerned that this rollback is not justified and that it could increase the chance of another major event. This article in the online journal The Hill is representative.

Further discussion is provided in the article White Whales and Black Swans.

Safety Moment #45: Inherent Safety

This week’s Safety Moment (Safety Moment #45: Inherent Safety) draws a distinction between the following types of safety:

  1. Inherent;
  2. Passive;
  3. Active; and
  4. Procedural

Of the four, the most effective is Inherent Safety because, no matter what happens, the system will always remain in a safe condition.

The Fundamentals of Process Safety Management


This week’s Safety Moment describes the basics of Process Safety Management (PSM) at

The article describes:

  • How PSM programs developed in the late 1980s in response to a number of catastrophic events that occurred at that time.
  • The successful decision to make PSM non-prescriptive and performance-based.
  • The fact that PSM is about process safety — and why that is such a challenge.

The article then discusses the three words that make up the phrase ‘Process Safety Management’, i.e., ‘Process’, ‘Safety’ and ‘Management’.

The PSM Report: Welcome

Sutton Technical Books

Welcome to the PSM Report — where the letters PSM stand for ‘Process Safety Management’. We post information, news and opinions to do with the management of safety in the process industries, including chemical plants, oil refineries, pipelines and offshore oil and gas.

Much of the material at this site is based on the following books: