Differences between on-spec and fit-for-purpose

Process Safety: Understand the Difference Between On-Spec and Fit For Purpose

May 15, 2023
Consider how changes impact the system and process safety

I recently visited South America. I spent a few days in Santiago, Chile, so I planned a small hike in the Andes. This was an ambitious goal, as I am not known for hiking. I had been planning this for a while, so I worked up a gym routine twice a week for over an hour each session. Lots of cardio exercise and every gym session included a vigorous leg workout. I was preparing well for the hike…or so I thought. Everything was going to plan, except my gym sessions were all at sea level. I had not factored in that I would be walking from around 7,555 ft to 8,530 ft. Only 975 ft up, but the starting altitude blew me away. I was fit, but not fit for purpose.

Many years ago, I learned the difference between something being on specification and something being fit for purpose. In 1999, several batches of AvGas were manufactured at the refinery where I worked. They passed every specification test, but they were not fit for purpose. They had a contaminant that was not detected in testing. This contaminant caused deposits to form on the fuel systems of the engines, resulting in engines losing power. No aircraft crashed, but around 5,000 were grounded until they could be cleaned. This was a huge lesson in understanding fit for purpose.

As I struggled walking up the track with my body receiving 25% less oxygen than I was used to, I noted that while I was on specification (I was fit), I was certainly not fit for purpose. So how did I manage to keep going? My guide offered advice on how to adjust, and he helped me manage the change. Like any other management of change, I needed to consider the risks and implement controls: Slow, deep breathing from my diaphragm with my head held high to keep my airway open. Small steps to avoid overusing my leg muscles, so they did not need as much oxygen. A steady, slow rhythm that allowed me to maintain deep breathing. These controls addressed the risk of not getting enough oxygen into my body.

Some days later, on the same vacation, I visited Iguazu Falls in Argentina. The adventure boat ride had a 500-ft steep stairway to climb. I was back in familiar territory now, much closer to sea level. That climb was easier, no rest stops were needed, just a constant pace up the stairs as I ascended from the riverbank. This helped confirm I was fit, as I had doubted myself after the Andes trip.

In any facility, we always need to consider the risks and ensure we are managing them with appropriate controls. Especially when we make changes, we need to ensure that different circumstances are considered. So, the next time you consider changing something in your facility, think about the change and how it impacts the system. Are their circumstances that make the change more or less risky? Was the system fit for purpose at the start? What additional or different controls are needed? How would you know the system remained fit for purpose? Have you considered all the necessary factors? How will the processes around the change interact with each other? Then make sure you implement the necessary controls.

I was so proud of myself for making it to the top of my hike. Once I reached the top, I continued the hike for another two hours at that altitude, before descending. Truly an amazing experience, and an important reminder of what is fit for purpose. 

About the Author

Trish Kerin, Stay Safe columnist | Director, IChemE Safety Centre

Trish Kerin is an award-winning international expert and keynote speaker in process safety and the inaugural director of the IChemE Safety Centre. Trish leverages her years of engineering and varied leadership experience to help organizations improve their process safety outcomes.

She has represented industry to many government bodies and has sat on the board of the Australian National Offshore Petroleum Safety and Environmental Management Authority. She is a Chartered Engineer, registered Professional Process Safety Engineer, Fellow of IChemE and Engineers Australia. Trish also holds a diploma in OHS, a master of leadership and is a graduate of the Australian Institute of Company Directors.

Her expertise has been recognized with the John A Brodie Medal (2015), the Trevor Kletz Merit Award (2018), Women in Safety Network’s Inaugural Leader of the Year (2022) and has been named a Superstar of STEM for 2023-2024 by Science and Technology Australia.