HART Forums  |  Login  


Home > HART Applications > How Comanies Use HART


BP Cooper River Uses HART Diagnostics to Save on Maintenance and Increase Productivity


PROJECT OBJECTIVES

  • Gain diagnostic data on hundreds of control valves to pinpoint problems during scheduled shutdowns
  • Migrate to new technology with minimal production downtime for installation
  • Make use of existing wiring and be compatible with existing valves and transmitters

2004

SOLUTION

RESULTS

“We are saving hundreds of thousands of dollars per year in maintenance and production costs,” reports a specialist at BP Cooper River, which supplies one-third of the world’s supply of a vital ingredient in plastics. HART technology improves communication from valves to analog and digital controls as well as maintenance

A. J. Lambert, an instrument and electrical reliability specialist at the BP Cooper River Plant in Wando, South Carolina, sought to balance two important goals: increasing plant availability without incurring additional maintenance costs. He achieved his goals, thanks to the application of engineering expertise, hard work and HART Communication technology.

The latter, he notes, played a key role. “We know of no other activity that can provide the kind of savings and plant availability that we are achieving using HART diagnostic data. We are saving hundreds of thousands of dollars per year in maintenance and production costs,” he says.

Located approximately 20 miles from Charlestown, the BP Cooper River Plant manufactures purified terephthalic acid (PTA), which is used in making polyesters, plastic bottles, and other items. Thus, while the plant doesn’t make plastic it does manufacture a vital plastic precursor.

There are two units on the site, one built in 1977 and the other in 1997. Between them they produce over 2.7 billion pounds of PTA annually, the largest amount of the product from any single location in the world. The plant accounts for nearly a third of the total global PTA production, with hundreds of employees and contractors on site. The Cooper River Plant runs 24 hours a day, seven days a week.

However, it doesn’t run all the time. Periodically, BP has a planned shutdown so that needed maintenance can be done. These scheduled shutdowns cost millions of dollars a day per unit. Before 2001, the plant would undergo a shutdown for maintenance purposes every couple of years.

During those times, the plant’s maintenance and engineering staff would pull 35 to 50 control valves out of a total of few hundred in both units. They selected the valves to pull based on various criteria, including past history and an assessment of wear and use from the manufacturing process. They didn’t have specific information pinpointing, which, if any, valves were causing problems.

As part of a plant-wide drive to lower expenses and increase availability, Lambert started looking at items that had the highest maintenance cost. After going over records for the unit built in 1997, Lambert “… identified 50 of the more critical control valves.”

Getting information on the health of those valves could be vital in meeting the overall goals of the Cooper River Plant. That meant intelligence had to be added to the valves, which in turn required the use of new technology. Any upgrade, though, had to meet certain criteria. Migration had to be easy and not interrupt current operations for any significant length of time.

The investment needed to be minor and benefits readily attainable. Those parameters implied that any solution would have to run over existing wiring and be compatible with the mix of valves and transmitters already in place, a combination that varied by plant unit. For instance, at the time the 1997 unit had smart transmitters but no smart positioners and an analog control system. The 1977 unit had a different blend of technologies.

Getting Smart

Around 2000, BP had spent thousands of dollars installing diagnostic software. At the time the project had been justified in order to get information from a single valve. That installation introduced the HART Communication protocol into the plant, and Lambert started looking into getting valve diagnostics from other locations using the HART signal. After a bit of investigation, Lambert and others were convinced that not only could this be done but that it could be done using the wiring already in place.

Therefore, they proposed a HART-centered upgrade, which plant management approved. The project was completed over the next few years without a problem. “The upgrade to intelligent positioners was phased in over time with no major disruptions to the operation,” says Lambert.

Because of differences between the units, various hurdles had to be overcome. One was the analog control system in the 1997 unit. The BP team solved this through the use of a converter, which transformed digital HART data from the positioner into 4-20mA signals that the analog control system could understand.

That same data, sans conversion, eventually also had to go into an asset management system that would eventually provide intelligence, data for analysis, and other benefits. For that, they used a multiplexer, sending digital data to the asset management system while allowing the analog signal to go to the control system.

Another hurdle involved handling valve position feedback. For that, the Cooper River Plant staff selected interface instruments to extract process, status and diagnostic data from the HART transmitters and valves. These provided actual valve position feedback and acted as position switches for the control system. They also eliminated the need for extra field devices and wiring.

By mid 2004 all of the positioners in the 1997 unit had been upgraded, while 10 percent of those in the 1977 unit were smart. While far from complete, the figure for the older unit includes the most critical control valves. Also at that time, some 150 transmitters and 125 valves were connected to the AMS.

Benefiting from Brains

The payback for this work, notes Lambert, shows up in a number of areas. For one thing, there’s been a reduction in valve maintenance costs. Whereas before, some 35 to 50 valves would be pulled during a planned plant shutdown that number has now been cut to only five or six. The maintenance and engineering groups know also why the valves should be yanked out of production before they’re pulled. The annual cost savings for this more accurate maintenance is in the hundreds of thousands of dollars.

Through the use of HART monitoring, the plant’s staff is able to monitor the health of half a dozen critical valves. They’re notified if those valves show signs of either freezing or overheating, allowing preventive measures to be scheduled and taken. This prevents those valves from causing unscheduled shutdowns, which can be very costly.

As a result of the upgrade, plant availability has increased to about 96 percent. One consequence is an increase in output. The installed capacity of the two units was originally 2.2 billion pounds a year. Through these and other improvements, that production has now risen to 2.76 billion pounds a year, an increase of more than 25 percent.

In the future, additional benefits are expected. Plans call for both engineering and operations personnel to begin using the data collected by the smart instrumentation to pin down problems and spot trends. By taking action based on this ongoing analysis, availability should go up and costs come down even more.

So the smart control valves, transmitters and HART Communication have led to both more paper, in the form of monetary savings, and more plastic, due to the increased plant output. The lesson for Lambert is that the payoff of the right solution to a problem could be large. “Get control of the items that touch the product and you can save some big money,” he says.