Hanging it all together

One company that has employed open wiring in a recent project in Florida is Air Liquide Process & Construction in Houston. The engineering company builds plants that generate hydrogen, oxygen and argon. According to Daniel Thouin, control system manager, a DeltaV system was chosen with Foundation fieldbus. Since it was a small application with about 20 transmitters, blocks and cables purchased from Turck were an easy-to-install, time-saving solution.. Thouin said that a bigger project with about 500 transmitters is in the offing, which may require a mixed environment of terminal blocks and cables/connectors to cover its longer distances.

There is a big demand for industrial networking systems with hardened cordsets says Masterson. In the process world, Foundation fieldbus is the most prevalent system, much of which uses armored cable for really nasty environments. Most applications call for junction bricks with quick-disconnect options that also must fit into Class I Div 2 environments.

Industrial Tubing and Fittings
For certain applications where nasty fluids need to be moved from point A to point B, metal piping is out. Polymers—better known as plastics—are in. Rockwood Electronic Materials (Riddings, UK) developed a new silicon etchant for its customers in the semiconductor industry. While the conventional chemicals for silicon etching are hydrofluoric acid and nitric acid, the new product improves process stability and surface quality in addition to reducing the amount of post-treatment.

“We have used George Fischer Piping Systems products for the last 20 years, says Andrew Hutchinson, facilities manager. “Over this long period of time, their valves have proven to be the most suitable for our applications. Even though we put them into a harsh chemical environment, they tend to last the longest.” The valve and piping tolerate more than 300 different chemical mixtures in the plant, and work in ambient temperatures from -10° to 50° C and maximum pressures to 6 bar.

Harsh and caustic flows need special piping. Temple-Inland, a pulp and paper producer in Silsbee, Texas, pumps large volumes of green liquor throughout its process. With a pH of 14, green liquor is an aqueous solution of sodium carbonate, sodium sulfide, sodium hydroxide and sodium sulfate. The solution has a tendency to quickly form carbonate scaling in pipes, reducing flow rates. George Pemble, a project engineer-group leader, found that the process was down 50% of the time due to scaling. “We were using basic carbon steel pipe, and were required to shut down our density control system for green liquor every other day and flush it for long periods.”

Working with a Plastic Lined Piping Systems local rep, Pemble made the decision to design the density control system around Halar (ECTFE)-lined pipe for three reasons. First, ECTFE has anti-stick characteristics and a smooth finish. Second, it handles the caustic liquor, and third, it can operate at 180°–190° F. Pemble installed several hundred feet of ECTFE lined pipe and fittings in 1.5 and 3.0 in. line sizes.

Pemble says that since the installation, the scaling problem is basically gone. He flushes the system briefly every other week to remove soft sediment that collects in the pipe.

NeSSI—An Evolving System
Instrumentation systems that take samples and conduct analyses online used to be rather large and often took several months to build. Today, NeSSI systems let engineers put together sampling systems that look like stainless steel versions of Lego blocks. Originally, the system was conceived as a plug-and-play system for valves, sensors, and tubing, but newer versions of it will include built-in fieldbus as well.

Rick Ales, marketing engineer at Swagelok and NeSSI’s secretary, explains, “NeSSI can be thought of as a “two-rail concept.” One rail is the fluid interface and the other rail is the electrical interface. Sample systems that implement the fluid interface or mechanical rail as defined in ANSI/ISA 76.00.02 are considered NeSSI Generation I systems. Adding the electrical rail or the NeSSI Bus interface to a NeSSI Gen I system gives us a NeSSI Generation II system. The latest draft specification for NeSSI Gen II systems is available on the CPAC website.

“Swagelok released the first NeSSI Gen I-compliant platform, MPC, in January of 2003. Since then we have seen industry acceptance building and the proliferation of third-party components. End-users are asking suppliers to deliver completely assembled systems rather than supply individual components as the number of NeSSI systems in service continues to grow. In fact, at many companies where it is in service, NeSSI is beginning to be thought of as a best practice.”

According to Ales, Getting Generation II moving has been a challenge, with the biggest hurdle being settling on the right NeSSI Bus technology. From the beginning, a Controller Area Network (CAN) had been the preferred bus technology, but unfortunately CAN does not meet the NeSSI Gen II requirement for intrinsic safety. Two milestones happened in 2004. First, the NeSSI Gen II spec was adjusted to identify Foundation fieldbus as an acceptable technology for NeSSI Bus. Second, the technical committee for Sensor Technology of the Instrument and Measurement Society (IEEE) sponsored a draft standard, IEEE P1451.6, that would provide a Smart Transducer bus based on CAN technology. One of the goals is to have an intrinsically safe bus option that is designed to meet the NeSSI Bus requirements.

NeSSI is getting the support of major companies, several of which are working together. Parker and Honeywell recently announced an alliance to provide the process industry with an advanced system for sample analysis. The alliance combines the Parker IntraFlow line of surface mount flow control components with Honeywell pressure, temperature, and flow transducers. An early user of the system, Michelle Cohn, senior manager of the advanced characterization area in exploratory and fundamental research for UOP LLC says, “The modular flow system from Parker and Honeywell improved the productivity of our skilled staff responsible for developing and delivering new technologies in our labs and pilot plants.” She adds, “Total project time to install this system was reduced by two-thirds compared to conventional systems and only required half the normal amount of time by our professional staff.”

Faster to set up and the ability to handle nasty environments are the watchwords for modern connector technologies—whether they carry electricity or fluids, and in the case of NeSSI, both. Both can save plant engineers money in the long run.