A hot cutover post from several weeks ago featuring Emerson’s Aaron Crews prompted a question from another Emerson project professional to Aaron. The question described an upcoming hot cutover project and asked Aaron to share any additional thoughts he had. For those unfamiliar with this jargon, a hot cutover is the process of converting to a modern process automation system while the process is still running.
In addition to sharing the detailed step-by-step process developed by The Automation Group (part of the Process Systems and Solutions organization in Emerson), Aaron shared these thoughts with his colleague:
Hot cutover execution is not necessarily too tough of a task as long as you know what you’ve got. The most important thing about a hot cutover is to have all of your information together and organized. You’ll want to have survey information for all of your valves, including whether there are bypasses or hand jacks. If there are not bypasses on the valves, you’ll want to review those cases with operations and the process manufacturer’s engineers to ensure that they can lose that valve for a few minutes (maybe they can fill up a tank before cutting over the inlet valve, for instance.) If they can’t lose valve function, there might be a workaround – you might have cases where the valve is normally at 100% and you can use a mechanical stop to keep it from failing closed, etc. Find an instrumentation expert to help you with any of these situations.
From a software standpoint, it is usually possible to put the I/O point in manual or to bypass logic that uses the point, but it is (as always) paramount to know all of your control references and complex loop functions on both the new and old DCS. Again, as long as you have all of your information you are ok-it’s what you don’t know that can get you in trouble.
The other major planning task is the cutover order. We typically cut over by graphic since the operator will have to be operating off of two DCSs at once. Within the graphic, we cut over indicators first (temperatures and pressures before flows, generally), then control loops then shutdown loops.
Overall, we just try and stay organized and keep all the documentation together. We generate reports at the end of each day that list the proposed points to be cut over the next day. These reports contain any field survey notes (that valve information from earlier), drawing numbers, wiring information and controls references on the old and new DCS for each point. This list is reviewed with operations and the specific order and specific operational concerns or strategies can be discussed during a daily meeting with operations, engineering, construction and safety leads.
We also track cutover progress very carefully to ensure that we are staying on schedule, and we keep a master list of loops as a cutover sign-off document.
The specific cutover procedure per point is typically pretty systematic, except in those problem cases that you will have defined.
I hope you see a few nuggets of wisdom you can use in planning a modernization project which includes a hot cutover at your facility. Also, I hope that I still get cc’ed on emails like these. One never knows when a blogger might add a little visibility to a good email!