Your control system is the nervous system of your plant. It communicates every decision to the
control units in the field. It’s the reason operators know the state of the plant and the process.
Like the body’s nervous system, a plant’s control system is complex, particularly if it has grown
over the years and has changed significantly from its original design.
In this second of four white papers, we’ll show you how to minimize the risk factors in upgrading
your control system to meet the requirements of the new century.
Many plants in North America and elsewhere were built in the past century. For example, the
ExxonMobil plant in Joliet, Illinois, is currently the youngest oil refinery in the United States — and
it was built in the early 1980s. You may work in a plant that is well past its original life expectancy,
but you have somehow kept it working all these years.
Some process plants have done partial DCS upgrades, but others — maybe even yours — are still
operating with large parts of the original control system still in operation. You may have patched
it, upgraded it and coddled it along, but it may be well past its prime.
Worse yet, your control system wasn’t designed for the plant you have today — it was created
specifically for the plant that was built long ago. Think of all the changes that have been made
in that time, all the improvements in quality, throughput and enterprise integration you’ve
made — or would like to make — if only the control system would let you.
Do you have the ability to make rapid changes in product or product mix? Do you have adequate
physical security? Sufficient cyber security for the control system? How well does your safety
instrumented system work with the basic process control system? Is your control room an
operator-friendly workplace? Do you have enough I/O to add new sensors and controllers for .
How does the DCS’ HMI handle alarm management issues? Do you have a history of near-miss
accidents because the alarm management system doesn’t work well in crisis situations?
Do you have the ability to add an historian and an advanced process control package to your
existing DCS without much blood, sweat, tears and cursing?
Do you have adequate spare parts on hand for your control system? Are spare parts even
available anymore? For how much longer will the OEM support your DCS and how much is that
going to cost you?
If you are faced with these issues, you know you need to do a major upgrade on your control
system. You also know it’s a monumental decision — one an engineering team makes only once or
twice in their entire careers. A major mistake on a DCS upgrade is surely a career-limiting move.
The easy option is to rely on whichever OEM supplied the original control system, or did the most
recent upgrade. It’s the easiest option — but is it the right one? To determine the best choice for
your plant, you will need to do some serious pre-planning.
End-users do pre-planning because they know that front-end loading the engineering
requirements and design phase saves remarkable amounts of time, effort and money — and
it can prevent catastrophic mistakes. This reduces the possibility of expensive — and possibly
career-ending — change orders and cost overruns.
So, how do you do the pre-planning required for a DCS upgrade?