At the large manufacturing company where I have worked for 45 years, we have always had instrument calbration labs. Every piece of equipment has a sticker indicating when calibration is next due. Employees are not permitted to use equipment beyond the calibration due date or equipment which has bypassed the calibration lab.
Simply applying this process to gauges (and fitting a shut-off valve in series with each gauge) would solve this problem.
That's right, Chuck. Gauges are usually mechanical, and thus they break. When they break, they don't stop anything. All you lose is your ability to monitor what is happening out of sight. But that could be critical.
I agree, Ann, you have to take the source of this data into consideration. But even if it's half of the 25%, it's significant. Wika also listed a handful of recent plant explosions and speculated they were caused by failed gaugues. Since it's just speculation, I left it out of the story. But it does make you think.
Yes, GTOlover, it's hard to replace a gauge under high pressure -- or, if the gauge is way below the water -- as in the BP spill. I can see the potential human error that happens then the engineer looks at two gauges and one reads that everything is OK. The difficulty of dealing with a problem may lead the engineer to assume -- wrongly -- that the gauge showing building pressure is the broken gauge. If the author of the book on the BP spill is correct, that judgment cost lives.
Good point Naperlou. A simple electronic signal -- setting off an alarm on the control side -- when the measurement goes into its red would seem enough, especially if it's backed up by scheduled visual checks to make sure the gauge is working.
I believe the 25% figure. As much as we at Design News write about modern, networked, electronics technology, we often forget that not every plant is so up to date. Sometimes, if there's no reason to replace something, it gets old, and when it gets old, it often breaks.
25% seems like a relatively huge number, considering what kinds of warnings these gauges provide. That percentage might be high, seeing that it's from a company that makes gauges. OTOH, from what I've read many times, including in the comment sections to various DN articles, gauges in fact don't get monitored often enough, if at all. The BP Horizon example is perhaps the most dramatic recent one.
Rob, I agree with getting rid of gauges that are not used. But the usefulness of many gauges are not apparent until you have to diagnose and fix an issue with a piece of equipment or plant resource. This is also the time that maintneance guys find out that the gauges are broken or not working correctly.
Part of my strategy was to remove the gauges and place a quick-connect fitting in its place. Then when the need to view a gauge arose, pop one onto the fitting. However, I could see that in some enviroments (like chemical gases/liquids) this may not be appropriate. Also, it is really hard to install a hydraulic gauge onto a fitting under high pressure!
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