Domino Theory

Can ISA88 and ISA95 Knock Down the Barriers Between Batch and Continuous Processing?

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Dave Emerson, director of the U.S. Development Center for Yokogawa Corp. of America in Carrolton, Texas, says loss of operator knowledge applies to all processes in general. “Many companies are losing employees or watching their workforce get older, and process knowledge is leaving the company,” he says. “In some cases, processes have been running without problems for years, mainly because of the skilled people involved. When they leave, this information may not be passed on.” Unless the company defines the process in ISA88, that is.

Marc Leroux, marketing manager for ABB’s Collaborative Production Management, agrees. “The issue of skill loss is huge and much more complex than can be addressed by one standard. The continued implementation of standards like ISA88 and ISA95 greatly reduce the impact of the skill loss, but there is no one standard that does it by itself. That said, implementing ISA88-based solutions go a long way to reducing some of these issues.”

Dave Chappell, president of Complete Manufacturing Automation Associates in West Chester, Ohio, has married several continuous processes at Procter & Gamble to ISA88. “At Procter & Gamble, we have successfully created ‘hybrid’ process control applications,” says Chappell. “The results of these adventures exceeded expectations. Using the recipe management and sequencing capabilities of ISA88 improved the operational management and execution of continuous manufacturing, though gaining acceptance was quite difficult.”

ABB’s Leroux says one of the major issues in gaining acceptance is that engineering contractors and end users are focused on capital costs rather than operational excellence. “In many cases, the requirements are quite straightforward and easily implemented at the controller level,” he says. “Moving it up to the unit level improves OpEx, but it comes at a higher cost.”

Chappell says that getting ISA88 accepted by continuous advocates is a challenge. “There are groups that believe strongly in the superiority of continuous manufacturing, and they will go to great lengths to prove it, including rejecting any automation techniques that are shared with batch systems,” he says.

Emerson says one way around this problem is to not call it a “batch solution,” which can kill the idea from the get-go. “If you can address their process problems from a business standpoint—such as how do you handle product changes, or how do you document the process?—then you can introduce ISA88 concepts of modular automation, procedural control and tracking production without calling it batch.”

He also sees more acceptance of ISA88 in continuous processes because engineers with ISA88 experience are changing jobs. “As the pool of engineers familiar with ISA88 has grown and individuals have moved between companies and projects,” he says, “it has been natural for them to use their successful practices in batch in other areas. We are just starting to hear more of this in application papers and case studies.”

Honeywell’s Gaafar agrees and adds wryly, “We never mention the ‘B word’ to continuous control people. Instead, we tell them we have a standard framework for defining process operations, transition management and report generation. If they ask, we tell them it’s based on ISA88, but we never mention the word ‘batch’.”

Leroux also agrees. “Removing ‘batch’ from the descriptions is a start,” he says. “Another way, which ABB supports, is to use the standards internally for our own solutions. For example, ABB uses ISA88 as the mechanism for dynamically configuring analyzers in our Industrial IT for PAT solution.”

ISA95 model
Figure 3: ABB’s factory in Dalmine, Italy, produces medium-voltage switchgear products. The automated factory relies on ISA95 for communication to the business system layer, and uses the models for scheduling, processing, tracking and reporting of materials.
It’s also easier to get ISA88 into a new plant if the company doesn’t have engineers or operators who are biased against batch. Gaafar says one customer is building a new polyolefins plant and has no experienced operators on site. “The customer wants to be able to produce several grades at high rates with minimal off-spec product during transitions,” says Gaafar. “By using the ISA88 framework, we were able to define all the recipes, procedures and transitions for our Experion R300 control system. I am not sure if we could have defined all these transitions in any other way besides ISA88.”

Others are turning to ISA88 because they can’t find similar solutions on the continuous side. Zarichniak of Honeywell explains, “Tracking production runs in a continuous process is a nightmare with standard historian or data acquisition software,” he says, “because it isn’t set up to handle all the various procedures. Programmers can write ‘spaghetti code’ to tie it all together, but it is much easier to generate production reports using ISA88.”

ISA88 Engaged to ISA95

Many people view ISA95 as sitting atop ISA88 in the “missionary position.” Essentially, an ERP or other enterprise function tells ISA95 what to make; ISA95 relays this information to ISA88; and ISA88 tells the control system how to make it. Like many marriages, the problem has been that ISA88 and ISA95 don’t talk to each other very well because they don’t use the same definitions. Tools such as B2MML (Business to Manufacturing Markup Language) and BatchML (Batch Markup Language), developed by WBF, can be used to make the connection. 

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