Management of Change: Small and Large Changes
In response to yesterday’s post Management of Change: When is a ‘change’ a Change Bruce Kopple noted that ‘just installing a piece of tubing can result in disaster’. Not only is that comment true, it can be expanded as follows.
Large initiated changes that involve numerous modifications to equipment, instrument systems and administrative procedures will almost always receive a full Management of Change review. Small changes, which can often be implemented quickly and easily, are likely to receive fewer checks and reviews. Some of the dismissive terms sometimes used to describe small changes ― terms such as ‘quick and dirty’, ‘one minute change’ and ‘midnight engineering’ ― are indicative of this way of thinking. A moment’s reflection, however, shows that this line of reasoning is disingenuous. Indeed, experience has shown that it is often the small changes that lead to serious accidents.
In a recent post we commented on the Process Safety Beacon Are your P&IDs up to date? The Beacon report was itself based on a Chemical Safety Board (CSB) Investigation: Fatal Equipment Rupture, Explosion, and Fire at the KMCO Chemical Facility. Our discussion was to do with the trapped liquids and the importance of keeping P&IDs up to date. From the CSB report,
. . . the isobutylene release occurred when a piece of equipment called a y-strainer ruptured due to brittle overload fracture. Specifically, the cast iron y-strainer was installed within an area of the piping system that, unlike other portions of KMCO’s isobutylene piping, was not equipped with a pressure-relief device or otherwise protected from potential high-pressure conditions. Therefore, when those conditions developed, most likely due to liquid thermal expansion, the y-strainer was subject to high internal pressure and ruptured releasing isobutylene which formed a vapor cloud.
The CSB report was to do with updating P&IDs and process hazards analysis. (Was the strainer even visible, or was it buried under inches of cruddy insulation?) But one has to wonder if there may also have been a Management of Change (MOC) problem. Was the y-strainer was installed to take care of some operating problem some time in the past? And, if so, was that change formally evaluated? We don’t know, but the accident does reinforce the idea that small changes can be just as risky as large changes.
When does a MOC require?
MOC is regularly seen in the dynamic oil&gas business as a complex paperwork (almost touching bureaucracy), until something happens and everyone invoque MOC as a panacea.
Let’s have a look in this situation: a hydrocom oil reservoir was not provided with a cooling system, which in the really hot summer in the Middle East resulted to be a problem. Oil got hot and trending to Trip the Recycling Gas Compressor of a treating unit.
The remedy was easy: applying external water in the reservoir kept the temperature in the acceptable levels…
The rubber hose with holes was wrapped around the reservoir to ensure water spraying in different areas and it worked.
Does MOC required for this remedy?
Thank you so much for the post. I remember that at one in my career, I heard a comment that modifying a gas-trim pressure relief valve to become a liquid-trim relief device or replacing a gas-trim pressure relief valve incorrectly used on liquid service with a liquid-trim pressure relief valve was a small change which didn't require a Management of Change. In reality, gas-trim ASME Section VIII PSVs are tested on air while the liquid-trim PSVs under the same Code of Construction are tested on water so there is a significant difference between the two applications hence requiring a Management of Change.