Plants Pit New Tools Against Corrosion

Real-time measurements lead to better uptime and other benefits.

By Seán Ottewell, Editor at Large

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CorrTran Aqua also is helping in the development of inhibitors themselves. Designers can see very quickly if a new inhibitor is working.

Roxar Flow Measurement, Trondheim, Norway, a unit of Emerson Process Management, which historically has focused on monitoring corrosion in offshore oil production operations, is gaining ground at chemical plants, notes Kjell Wold, commercial manager. The variety of processes used in the chemical industry rules out a single solution, he adds.

Strong demands for improved data quality and more simplified ways of collecting [data] are driving the increasing interest, he says. "… People are happier with wireless these days and it gives you so much flexibility. There's been a definite change in attitude in terms of accepting wireless."

In response, Roxar has launched a new range of CorrLog wireless corrosion transmitters. These provide corrosion data in two formats: either directly to the control room as a metal loss value (due to corrosion or erosion), or as raw data through the company's Fieldwatch software. "This would be the preferred format for corrosion and production engineers but it depends on the business priorities."

The system's data logger comes with a 20-m cable. "This means that you can find the very best place in the plant for the transmitter," says Wold. Such flexibility can eliminate having to erect scaffolding when a battery or probe needs changing, he explains. Also, it can provide a way to avoid areas in shadow in a plant's wireless mesh network.

In mid-September, the company introduced Fieldwatch 3.0 (Figure 3). One of its roles is to reduce the number of false alarms received from erosion probes. During testing on historical data from the North Sea, the smart alarm software suppressed 99% of the false alarms and retained 100% of the genuine ones.

Fieldwatch 3.0 also enables installing virtual erosion sensors within a production system — these are particularly handy for monitoring bends, tees and reducers in areas where it's difficult to deploy physical sensors. Users configure the geometry and input pressure and temperature values that best represent the virtual sensor's position and analyze as they would with physical sensors, although the accuracy isn't as great.

"Using the data analysis features of Fieldwatch 3.0, decisions on optimizing flow velocities can be made… There's a similar use with chemical inhibitors: knowing when and how much to inject, for example. So, it gives much better process control. That's the beauty of the system because you can see and follow the corrosion at a nanoscale, before any damage appears on the pipes. So with continuous monitoring you can correlate corrosion rates with process changes such as, for example, water content and pH," adds Wold.

Seán Ottewell,Editor at Large, can be contacted via


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