Process automation at Dow: Part 2

By Maggie Walker, Ed Sederlund, Jerry Gipson and Eric Cosman, Dow Chemical Co.

MORE THAN 30 years ago, the Dow Chemical Co. embarked on what ultimately evolved into a global corporate initiative: to develop and broadly leverage a standardized, highly integrated process automation system, incorporating basic process control, process information, and safety-system functionality.

Based on what we wanted to accomplish, and a lack of commercial offerings at that time, we developed several proprietary solutions, including a process control system that came to be known as MOD, which is short for “Manufacturing Operating Discipline.” With its MOD 5 System, Dow was the first company to certify a process automation system with logical separation of the control and safety functions.

Our development approach served us well for many years, but we reached a point where it was no longer cost-effective to develop our own system. Part 2 of this three-part series describes Dow’s transition from our successful, homegrown solution to a commercially developed solution, including what went into the decision process, why we needed to change, and how we grew and nurtured a truly collaborative, technical relationship that will take our operating discipline forward.

From the beginning, continuous improvement has been at the heart of the Dow Chemical Co., and forms the essence of its mission today, “To constantly improve what’s essential to human progress by mastering science and technology.” To achieve this, we’re committed to the principles of Sustainable Development. As we discussed in Part 1 (“The Mod Squad: Process Automaton at Dow,” CONTROL, Feb. ’06), this underlying philosophy has been an instrumental driver in our process control journey.

The roots of Dow’s process-automation philosophy go back to the 1960s, and are based on our operational strategy. Consistency and sustainability are key elements of that strategy. As a global company, it’s important to operate facilities the same way, every time, to achieve consistent high quality, as well as process reliability and repeatability of best practices.

Of course, safety performance also is a key focus for Dow. Protection of people, the community, and the environment have always been non-negotiable priorities in our corporate culture. We must operate our plants safely every time, as well as the same way every time. Our "Vision of Zero" translates to zero incidents, injuries, illnesses, accidents, and zero environmental harm. So our safety practices needed to be repeatable and re-deployable, too. All of these elements made up our Operating Discipline (OD).

Initially, commercially available process automation systems didn’t give us the capability we needed. Technology was available that could be applied to the problem, and we developed several solutions based on general-purpose computers and operating systems. As we gained experience with these systems, it became evident there were significant shortcomings when applied to process automation and customer needs. Over time, we developed the MOD 5 system to meet our needs (See Figure 1 below).

	FIGURE 1: MOD 5
	With its MOD 5 System, Dow was the first company to certify a process automation system with logical separation of the control and safety functions.

For nearly 30 years, and with more than 15 patents related to MOD technology and TUV Safety Integrity Level (SIL) 3 certification, we enjoyed continued success in fulfilling our OD with our proprietary MOD System series. It grew from an analog system at one site in the 1960s to a globally deployed, standard process control system with 1,500 systems installed throughout Dow by the year 2000. Over the years, the MOD series system delivered tremendous productivity benefits to Dow. We reduced the time to develop control strategies by 45%, and reduced support costs by 50%. Process startups were automated and coordinated across multiple-unit operations. Alarms were “intelligent,” reflecting the state of a process, rather than just a deviation from a limit. Batch processes were fully automated, resulting in reduced cycle times. Imbedding the OD concept in the automation system also helped us achieve our Environmental, Health and Safety (EH&S) goals. All of these performance improvements jointly contributed hundreds of millions of dollars in value to our businesses.

Exploring New Sustainability Solutions
In early 2000, however, we realized it wouldn’t be cost-effective to continue to invest in proprietary hardware and software systems. Our efforts to develop the next version of the MOD system, MOD 6, proved to be much more time and cost intensive than we anticipated. MOD 6 development began in 1987, and envisioned a triple-redundant, synchronous architecture built on dual-redundant synchronous architecture learnings from the MOD 5.

The strategic error in MOD 6’s development was building our own computer and communications application-specific integrated circuits (ASICs) and related software and development tools. MOD 6 was successfully demonstrated in 1998. However, rapidly changing computing and automation technologies, such as changes in networking, connectivity, communication protocols, integrated systems, real-time information access, and embedded intelligence made it difficult for us to incorporate all of them into the current development cycle, which became more unwieldy to manage with each passing day. It seemed that we’d come to the crossroads where commercially available technologies were at long last catching up to us.