June 10 2015
By: Clive Wilby
The Center for Chemical Process Safety (CCPS) defines Management of Change (MOC) as:
"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, feed stocks, mechanical procedures, electrical procedures, safety procedures, emergency response equipment from the present configuration of the critical process equipment, procedures, or operating limits."
Or as stated by the U.S. Chemical Safety and Hazard Investigation Board (CSB):
"In industry, as elsewhere, change often brings progress. But it can also increase risks that, if not properly managed, create conditions that may lead to injuries, property damage or even death."
On June 1, 1974, the Nypro cyclohexane oxidation plant in Flixborough, England was destroyed by an explosion. There was a release of 30 tons of cyclohexane to the atmosphere that formed a vapor cloud ignited by an unknown source about 45 seconds after the release. The resulting explosion destroyed the entire plant, resulting in the death of 28 people and 89 other serious injuries. The number of fatalities would have been much greater had the accident occurred on a weekday when the administrative offices would have been filled with employees. The damage extended beyond the plant to 1,821 nearby houses and 167 shops and factories; total property damage reached $63 million.
The Flixborough explosion was the result of an unwise plant maintenance modification. In short, there was no MOC process in place, and it was as a result of this incident that the regulators such as HSE introduced MOC as part of Plant Safety regulations (i.e. COMAH in the UK). If an MOC system has been in effect at the plant, the explosion might have been prevented. The MOC system would have called for a proper safety review, adequate approval at all stages of the change process, and a design created by trained professionals.
One of the main recommendations of the Flixborough inquiry was:
"Any modification should be designed, constructed, tested, and maintained to the same standards as the original plant."
Many of our safety regulations, analysis methodologies, and technologies that we use today have evolved as a result of incidents such as Flixborough, Piper Alpha, Bhopal, and many more.
Thankfully, not all MOC related incidents are as severe as Flixborough, but these minor day-to-day infractions should be a big red flag, as they nevertheless have an impact on an organization. If not resolved, they are likely to result in far more severe consequences.
MOC and related permit to work activities can be viewed as a burden on Operations and Maintenance personnel who are already working overtime on managing their daily activities of running the facility efficiently. However, MOCs must be implemented in a robust fashion and appropriate resources must be allocated.
The number of MOC a typical plant processes can be summarized in the following statements by Ian Sutton Ref (Process Risk and Reliability Management June 2009 http://www.stb07.com/):
- 250 MOCs per year for a medium-sized site of say 140 employees
- 1,000 MOCs per year for a large site of say 2000 employees
- 1,400 MOCs for a world scale Refinery
How good is your MOC system, and can you safely and efficiently handle the MOCs in your facilities? Take into consideration the following questions:
- Can your MOC system provide the following Key Performance Indicators (KPIs)?
- Percentage of MOCs past due date
- Percentage of MOCs properly executed
- Percentage of audited changes that used MOC prior to making the change
- Number Temporary changes still to be MOC-ed
- Number MOC performed per month, and monthly average
- Percentage of work requests classified as a change
- Percentage or variation in the number of changes processed on an emergency basis
- Average backlog of MOCs/active MOCs
- Average time taken between MOC origination & authorization
- Percentage of work orders/requests that were misclassified as replacement-in-kind (RIK) but should have been MOCs
- Ratio of identified undocumented changes to number of changes processes by MOC
- Percentage of changes that were MOC-ed but reviewed incorrectly
- Percentage of MOCs that were not documented properly
- Percentage of MOCs for which drawings and procedures were not updated
- Percentage of temporary MOCs where the temporary conditions were not corrected/restored to original state by the deadline
- (#MOCs/#MOCs+#changes that by-passed MOC) *100%
- Can you conduct a complete and thorough impact assessment to show all related data and information that needs to be reviewed and re-validated as a result of the proposed MOC (e.g. trip and alarm setting, procedures, LOTO, cause and effect diagrams, etc.)?
If you can confidently answer yes to these questions, you have a robust system in place and are in control. If not, we recommend reevaluating your MOC processes to help ensure your MOC system can effectively and safely process the large volume of MOCs that may flow through your facilities.
