I always thought that gauge audits were commonplace. I've seen everything from antistatic mats all the way to HVAC systems being audited. There have even been times when production was shut down or had to rent gauges to get through a current audit
As a one time maintenance manager I recall spending considerable time and money to fix or replace a bunch of gauges. Although these were water pressure, air pressure, HVAC, and hydraulic pressure gauges, the effort was to ensure all gauges worked in our plant. One week after completion, I did a quick audit and found several damaged. I never found the person named "I don't know" but he sure had a habit of damaging gauges. It seems that many of the gauges are useful foot steps, hangers for tools or clothes, and grab handles for reaching over piping. So it does not surprise me that many plants, including chemical, have broken or non-functioning gauges.
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.
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.
Rob, as many have pointed out here, correctly working gauges and meters are only as good as the people reading them--or not reading them. The BP disaster was due at least in part to faulty oversight, i.e., lack of/incorrect monitoring.
That's right about BP, Ann. One of the gauges was working and indicating that pressure was building. Instead, BP personnel chose to trust a broken gauge that indicated everything was fine. At least, that's what the book on the accident claimed.
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.
But if the gauge were that important, I doubt it would be permitted to degrade as much as those shown in the images.
One solution is for Wika to build more robust gauges. Most gauges use their port as the structural mount. The process medium (compressed air, chlorine gas) could easily vent if the damage to the gauge includes that port. Beefing up the port can help some of what Wika shows.
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!
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.
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.
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.
One solution is to network and instrument the guages. Today this a very inexpensive proposition. In addition to helping with monitoring the plant, it would help to characterize the guages and systems they measure over time. Just throwing out a measurement instrument in a plant today seems a little archaic. Think about the instrumented composite wings Ann talked about recently.
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.
Rob; One issue about gauges is they are usually direct plumbed into whatever they are monitoring. Thus a broken gauge replacement requires shutting down that entire line and exposing the contents to contamination from outside or vice versa. Putting gauges on shut-offs that permit removal without leaks and making all gauges moveable such that the 'normal' is always in the same orientation. For most processes, gauges are 'trendicators' more than an accurate readout. The percentage of defective gauges is not surprising but what may be surprising is the number of gauges that no longer serve any purpose.
Bob from Maine, I suppose one approach to this is to replace the gauge during scheduled downtime. That would mean some gauges would be inoperative during the wait for downtime, but that may be the most efficiently way to deal with this problem.
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