Procedures govern the world of process automation. While we like to refer to the process industries as being largely "continuous," in actuality, process manufacturing is constantly in flux.
Whether you are doing a startup, shutdown, grade change, or are in the middle of a maintenance turnaround, your plant is governed by procedures and transitional states that can either run smoothly and provide you with nearly seamless grade changes or product changeovers and safe and orderly start-ups and shutdown; or they can cost you in terms of unplanned shutdowns, incidents, lost product, and lost opportunities.
In demand-limited manufacturing industries, the overarching objective is to improve utilisation. Plants cannot achieve this without reducing unplanned downtime.
ARC research shows that the largest reason for unscheduled downtime is operational or human error, which accounts for approximately 42 percent of the unscheduled shutdowns in the process industries.
Of that 42 percent, 16 percent is directly related to procedural error. When researching the role of operators in the refinery of the future, several major operating companies concluded that this can be addressed through a high-level perspective that enables flawless intervention by exception and relieves operators of manual tasks, freeing time for more value added activities.
The same research also identified procedure automation as one of the key process automation system functions (along with alarm management and an operational perspective) that can support this environment of flawless intervention.
The expertise and operating level of experienced operators can be incorporated into automatic sequences and used to standardise operating methods and improve the efficiency of all operators.
An important part ARC's vision for the collaborative process automation system (CPAS) of the 21st century is that, in developing an overall automation strategy, humans should be allowed to do what they do best and automation should be allowed to do what it does best.
Humans are good at ad-hoc intervention and non-linear reasoning. They do best when empowered with an overall production cycle perspective. Machines and automation are good at repetitive functions, steady state operation, and managing transitions.
Automation provides an environment for unbroken, precise execution, linear reasoning, and can consistently implement best practices through automated procedures.
Today, operational procedures can be lumped into three primary categories: manual, prompted, and automated.
In manual procedures, the operator performs the necessary actions required either through personal experience or by following standard operating procedure (SOP) manuals.
The consistency with which manual procedures are performed can vary greatly depending upon the level of experience of those carrying out the procedures. Manual procedures also call for manual record-keeping, which can also vary in consistency and quality.
Electronic records are preferable, but their quality can also vary depending upon the accuracy with which they were entered into the system. There is no way to verify that the manual procedures followed were in fact consistent with printed SOPs.
Prompted operational procedures go one step further. Here, the procedures are implemented in the process automation system and the operator is prompted to acknowledge that each step has been successfully completed in order to continue.
Prompted procedures make it easier to keep electronic records and verify that procedures were followed correctly. They can also decrease both transition times and product variability.
Like prompted operational procedures, automated procedures are implemented in the process automation system.
The difference is that automated procedures will go through the entire operational sequence before stopping, unless either the operator or the system intervene on an exception basis. Automated procedures can further reduce transition times and variability.
Many industries have been using prompted or automated procedures for some time. The batch processing industries such as food and beverages and specialty chemicals have used the ISA-88 standard for years.
This defines a modular approach to batch automation and batch procedures. In refining, petrochemicals and other continuous process industries, the emerging ISA 106 standard, introduced in 2012, is fulfilling the same role.
This is not to say that automated procedures were previously unknown in the continuous process industries. Many companies have implemented sequence logic that allows procedures to be automated.
However, these have been done largely in an ad hoc framework using custom programming methodologies that can become cumbersome when it comes time to upgrade the automation infrastructure. This ad hoc approach also carries a high cost of ownership, since the procedures have to be maintained by the end user.
Changes made to the code over time can create a tangled mass of "spaghetti code" that can be impossible to translate.
Many end user companies in the process industries today are also the result of mergers and acquisitions. Along with that come the many system platforms and unstructured code implementations that have accumulated over the years. Clearly, this is not a sustainable way to do business.
As a result, more and more end users are standardising approaches and many have either already adopted, or are considering automating startups, shutdowns, grade changes adopting procedure automation.
[Dave Woll is vice president, ARC Advisory Group.]