A CYA culture and fear of failure are poor reasons not to imagineer an all-digital plant.
If you watched the "extras" on your "Wreck-It Ralph" Blu-ray disk, you might have found an animated sequence of significant length that was never seen in the released movie. The story and the plot were changed in the midst of production. Disney executives, one supposes, have learned over the years that creative people will spawn brilliant ideas throughout a project, and they'll take a gamble with budgets and schedules if a good one comes up in the midst of execution. The notion of a "P&ID freeze," or whatever its analog is in the movie business, just isn't there.
Process plant executives have more staid investors, and their tolerance for "creativity," especially late in a project, wears fairly thin. But in 1998, when plausible fieldbus solutions had credible support across multiple platforms, it seemed to me a sad compromise to forgo an open, all-digital solution for decades-old analog technology or limited proprietary solutions.
We were fortunate when our primary field device supplier also became the DCS supplier for the project, and expressed its conviction, commitment and support for selecting fieldbus. In large part, its becoming effectively the main automation vendor is a big part of why the plant in question rolled the dice as an early adopter, and has enjoyed 14 years of operation with all regulatory control using Foundation fieldbus. The plant manager says he's never worked in a plant where personnel had so much confidence in their measurement and control system.
How often is it that project priorities align favorably with those of the operate-and-maintain organization that's expected to run the plant safely, reliably and profitably? Many engineers and designers have been in the throes of detailed engineering, where the piping and instrumentation diagram (P&ID) is frozen, while the operations group grows in its understanding of the challenges of operating the plant. If another spare pump is desired, another measurement or valve is needed, it becomes increasingly expensive and complicated the further the job progresses. No project manager wants to be called before the finance guys to explain why the budget and schedule they approved has been tattered. This isn't Disney.
If you've been in our profession for awhile, it's possible your appetite for creativity and imagination has become similarly constipated. The stresses, perils and, in some cases, the madness of project execution, can foster a risk-averse CYA culture that grasps for guarantees, certainty and diluted accountability. Indulging in this culture may help you survive the battles, provided you're happy waking up in the same foxhole.
You can help projects seem more like the "happiest place on earth" by choosing an intelligent device management strategy early in the design—if possible, before the first instrument index is derived. That way, the project team and the client can not only budget for any increased cost and effort in the project, but also plan roles and staffing, so they're exploited throughout construction, commissioning and routine operation of the plant. Such investments can pay for themselves through faster and more reliable commissioning and start-up, and minimize the impact on the budget by bundling intelligent device management licenses and training with host procurement.
While the hundreds of registered fieldbus products, including nearly 20 host systems from 11 different suppliers, may tempt the creative to mix-and-match, it's wise to limit bidders to a select few. A pre-procurement effort is worthwhile to lock down a short bid list or even select a main automation vendor.
It's not necessary to stifle your imagination and creativity to efficiently execute a project, and selecting a main automation vendor doesn't mean you have to settle for proprietary solutions. But before the plot thickens, dare to imagine an all-digital plant where the capabilities of intelligent devices are fully exploited.