If you talk to a safety engineer in a “boomable” plant, such as an oil refinery, and suggest that the safety systems for critical and dangerous units should depend on the internet, you might not receive a receptive answer. “Are you nuts?” would be the most-polite response you could hope for.
So what is Mark Menezes suggesting in his article, Industrial Internet of Things in Safety Applications, appearing as the web-exclusive for InTech, March/April, 2018? Is he suggesting safety on the Internet? In a word, no, but that doesn’t mean Internet-based applications should not be used to support safety functions.
Manufacturers are still a long way from using IIoT to support safety instrumented functions (SIFs) directly in plants handling hazardous products, but it is practical to use the IIoT to help ensure the SIFs can do their job.
One of the perpetual questions safety engineers ask is, “Will a given SIF do its job in the heat of an incident?” They do their best to make sure the answer is yes, but is it ever possible to be completely sure?
Safety engineers understand how measurements can be extremely safe under laboratory test conditions referenced in typical failure modes, effects and diagnostic analysis (FMEDA) reports, but they can become unsafe when exposed to real-world conditions. Some of the elevated safety risk is due to interface failures.
Mark is making a critical point here. Safety functions should not be dependent on the Internet, that part is clear. But, no system, even a safety system, is infallible. Things can fail for a multitude of reasons, and IIoT-based functions can help keep an eye on the safety system equipment to make sure it is working so it can perform its safety function during an incident. This is important, because if a safety device fails, nobody might know about it until it can’t do its job during an incident.
Unfortunately, while failures of devices needed for physical protection or plant emergency response are common, users typically only discover these failures during occasional manual inspections, or when the equipment does not respond in a true emergency. This is where IIoT can help. Pervasive sensing technology, using secure and reliable wireless communication supported by advanced analytics, can replace manual inspections with continuous online monitoring. The benefits are significantly better process safety and reliability, lower cost, and less risk from manual inspections.
So we can use the IIoT to monitor parts of the SIS to make sure they’re able to do what they need to when the time comes. The article provides a bunch of examples, so it’s well worth a careful reading. Here’s just one example, pressure relief valves, and you probably have lots of them in your plant.
Because PRVs are simple mechanical devices, there are no internal electronic elements capable of providing diagnostic functions. However, new acoustic instruments can be clamped onto the pipe downstream of the PRV to identify a full release immediately, as well as ongoing leaks from incomplete valve seating. PRVs often simmer, releasing small amounts of product before pressure reaches the full release point. An alert operator can use an acoustic instrument to detect simmering, possibly early enough to adjust the process and avoid the release entirely.
Think of it as an extra warning before an incident. Maybe you can adjust the process to reduce pressure in that part of the unit and avoid a full release. This kind of advance action is possible because the acoustic monitoring instrument sends its data via the IIoT. It isn’t the safety device, but it helps you know what the safety device is doing.
There are all kinds of instruments capable of doing these types of monitoring functions for a variety of plant assets. Using them effectively depends on having the infrastructure to capture and analyze the data they produce. This is what the IIoT was made for.
To maximize the safety and reliability benefits, the devices described so far should be monitored continuously from a central location. Ideally, the equipment supplier should provide not just devices, but analytical software to interpret the signals from existing wired and new wireless devices and advise operators and maintenance technicians only if action needs to be taken. The system can even describe the nature of the problem and recommend corrective actions to keep the plant safe and reliable.
Emerson’s Plantweb Insight is exactly what the situation calls for. It provides the kind of specialized analysis needed, without all the overhead and complex configuration of conventional platforms. Plantweb Applications such as Steam Trap Insight, Heat Exchanger Insight, Pump Insight, Pressure Gauge Insight—and more available soon—can be quickly implemented and easily accessed anytime, anywhere to improve your operations.
You can find more information like this and meet with other people looking at the same kinds of situations in the Emerson Exchange365 community. It’s a place where you can communicate and exchange information with experts and peers in all sorts of industries around the world. Look for the WirelessHART and IIoT Groups and other specialty areas for suggestions and answers.