Safety Moment #5: Management of Change — Defining Change

Management of Change — Defining Change

The information provided here has been extracted from the ebook 52 Process Safety Moments.


Management of Change (MOC) is rightly recognized as being at the core of a successful Process Safety Management (PSM) program. Indeed, it could be argued that all undesirable incidents on an operating facility are due to someone, somewhere making an uncontrolled change.

But, when implementing and running an MOC program, process safety professionals face the challenge of defining the word ‘Change’.

Consider the definition for MOC provided by the Center for Chemical Process Safety (CCPS).

A temporary or permanent substitution, alteration, replacement (not in kind), modification by addition or deletion of critical process equipment, applicable codes, process controls, catalysts or chemicals, feedstocks, mechanical procedures, electrical procedures, safety procedures, emergency response equipment from the present configuration of the critical process equipment, procedures, or operating limits.

Some of the words and phrases used in this definition merit discussion.

  • Not in Kind
    Most MOC programs state that, if a change is “in kind” or “like to like” then there is no need to follow the MOC process. But the term “in kind” is more tricky than it may initially sound. When pushed to the limit all changes can be seen as not being “in kind”. For example, two “identical” equipment item parts will have a different history — they could have been made at different times, or in different factories or by different people, and have been stored in different locations under different conditions. In the great majority of cases such differences will not be significant. But there may be occasions when an item that is treated as being identical to the one that is replacing is different enough that an incident may occur.
  • Critical Process Equipment
    Identifying some equipment items as being “critical” and others as being “non-critical” can lead to question-begging. This critique of the term “criticality” as used in this context is not just theoretical. Examination of actual incidents shows that some of them were triggered by an apparently non-critical change.
  • Operating Limits
    The operating limits of many equipment items are not known (a challenge faced by many hazards analysis teams). In some case the only way that operating limits can be defined is by running that equipment until conditions become unsafe. This is, of course, unacceptable.

With all of these issues there is a danger of falling into the trap of circular logic on the following lines,

  • Is the proposed change critical?
  • We will have to run it through the MOC program to find out.

. . . . .

Additional Information

Further discussion to do with Management of change is provided in the following publications:

You are welcome to use this Safety Moment in your workplace. But there are restrictions — please read Use of Safety Moments.

Copyright © Ian Sutton. 2018. All Rights Reserved.