What would happen if I asked various people in our industry, “Which control valve in your plant will you have to repair in the next turnaround?”
You’d hear “I don’t know” a lot.
Usually in turnarounds, operators pull control valve without knowing if they need corrective maintenance. Once they verify the control valve conditions, they’ll replace items or whole valves, even those in good shape, spending money on unnecessary fixes.
Most valve positioners today provide diagnostics to tell maintenance crews when to take preventive or predictive actions. Sadly, many companies ignore this information and waste money in their turnarounds.
So how can you know which valve to repair in the next turnaround? By controlling the life cycle of your valves and analyzing the diagnostics from your valve positioner. In conventional plants with 4–20 mA communication, how can you use 100 percent of the potential from your SMART field devices?
By using wireless to send all HART data to the plant asset management (PAM) system. Yes, in this scenario, we want to use wireless where we already have cable, cutting the cost of the PAM system.
You can also try a multiplexer or change programmable logic controller (PLC) cards, for example from analog to HART. Sometimes these options can trim costs or make your PAM system run faster. You can install the wireless solution in parallel with 4–20 mA communication. It won’t interfere with or influence the signal, either, which makes installing it easier and decreases costs.
Of course, you’ll need the right software to access all data from your devices. Maybe you didn’t know, but most brands use proprietary software to grant access to the valve positioner. However, you might have a way around that. Getting diagnostics directly from field devices without proprietary software requires a brand that can send all functions and diagnostics directly to the device type manager (DTM) or device description (DD) files.
Even when a company has a digital network like PROFIBUS DP/PA or FOUNDATION Fieldbus, it may still fall short of reaching its potential with the network. Indeed, often plants use their digital field networks as simple analog networks for remote access, losing their diagnostics.
In these cases, the companies must review their maintenance systems. A PAM system provides access to all diagnostics from each field device. And predictive maintenance gives you the key to getting the most value from a PAM system. If you can analyze your diagnostics before your device develops a problem, then you can act to prevent that problem.
Maybe you want to hire an external service to verify your valves with a universal tool throughout your plant. You can do that, but a PAM system will probably serve you better. With it, you’ll receive data from your devices all the time, thereby opening the door to predictive maintenance.
Original publication at Visaya Solutions on medium.com