Pressure Gauges: Hidden Danger or Visible Safety
1332-221CL-FA2018 Process facilities have been tasked with a bigger workload within the past couple years, and have not been provided the resources they need to handle the increased capacity and the on-going equipment maintenance. With the call to produce more with less resources, puts stress on the equipment and the instrumentation. Heavier pressures and vibrations are converting to areas within the process industry, and most importantly, the instrumentation.
Faulty or broken gauges can cause a number of problems, but the main one is safety. The most common results of faulty, or damaged gauges is the leaking of media from the instrumentation. These leaks can cause harmful vapors, corrosive material, or fires within the process. Another problem with defective gauges, is that it can lead to very expensive shut downs. If the malfunctioning gauges cause a serious problem within the process, the unit will have to shut down and this can take anywhere from a day, to a week, or a month, depending on the seriousness of the issue. This can lead to very expensive setbacks.
There are seven categories that unreliable pressure gauges can be looped into, due to the cause of the failure. The first, is mechanical vibration. Any type of equipment can produce vibrations that can damage instrumentation, with pumps being the worst. The second category is pulsation. This is due to the media causing a pressure fluctuation. Temperature is the third category of failure. Process variables can affect the way instrumentation reacts to temperature. A solution to this problem is the place the gauge further down the process, or to install it in a spot that has an increased flow of air. Spikes or overpressure leads to the fourth category. Pumps can cause a violent spike in pressure, which leads to damaging a gauge. Surging or spiking can lead to the cause of the Bourdon tube rupturing. The fifth category is Corrosion. If the gauge is not made to specification of the media running through it, it can corrode the Bourdon tube and leak onto the ground or onto other process equipment. Clogging is another problem and it is the sixth category. Some media can solidify in the gauge and cause the instrumentation to not perform correctly. Viscous materials and hard substances can clog gauges. Mishandling and misapplication is the biggest cause of failure. This is where a gauge was not properly installed, was not serviced correctly, or changes happened in the process that makes this gauge not compatible anymore.
Placek states, “Gauges are often viewed as inexpensive commodities, with management failing to realize that they are very critical parts of the processes.” This is due to the company focusing their investments on larger, more expensive, pieces of equipment. Instrumentation tends to get looked over because they are relatively cheap. Another issue, is the lack of education. In the early years, there were designated workers that would install and service the instrumentation, but plants started letting them go. This caused the responsibility to fall on the pipefitters, but it was not their main job. After the plants started to migrate these workers out, the job fell to the operators and technicians. Operators don’t know the in’s and out’s of instrumentation and have not been trained on the topic.
Companies have started to outsource all trades that they do not believe is at the core of their process, which includes instrumentation. Due to this, if a plant does not want to get the experience and education it needs to service the instrumentation, there is assistance available with WIKA. They have developed a “Full Audit Service Team (FAST)”, which is a group of engineers that go around to the process plants and conduct audits free of charge.
Pressure Gauges: Hidden Danger or Visible Safety from EHS Today and New Equipment Digest: