March 2011’s meltdown at Japan’s Fukushima Daiichi nuclear power plant offers a compelling case for carefully selecting and regularly checking pressure gauges to ensure plant safety in any type of facility.
According to press reports, initial readings from gauges inside Daiichi’s reactor one reported a water level of 550 millimeters above the top of the fuel assembly—far below normal safety standards but enough to assure operators that no fuel had melted yet. But, months later, calculations showed the superheated water inside the pressure vessel had dropped below the bottom of the uranium fuel rods, leaving the reactor core completely uncovered. The fuel rods’ protective zirconium cladding began to react with the steam, causing the uranium inside the fuel rods to begin to melt.
Not every facility has the potentially volatile conditions of a nuclear plant, but that doesn’t make careful pressure gauge selection and maintenance any less important. Based on more than 250 Instrument Audits, WIKA has found that almost 25% of gauges in a typical processing plant require corrective action.
Failure to select and monitor the correct pressure gauge can result in significant plant downtime. In a worst case scenario, an improperly maintained pressure gauge can fail to measure pressure during an overpressure event, compromising plant safety and potentially resulting in costly damages.
Phase media compatibility
- If the phase media is not compatible with the wetted parts of the gauge, corrosion most likely will occur.
- Requirements differ from one industry to another, but for most process plants WIKA’s guidelines state that +/- 0.5% accuracy is the norm but +/- 1% is acceptable.
Case style and material
- Ambient temperature, airborne particulates, condensation, humidity, water, and chemicals can affect the overall performance of the pressure gauge.
- The pressure gauge’s plant history in similar scenarios is a good measurement when selecting a particular pressure gauge. Consider lifetime cost, ease of maintenance, and interchangeability.
If you’re concerned about the reliability of gauges in your facility, WIKA’s Full Audit Service Team (FAST) offers a comprehensive array of services, including Instrument Audits, Turnaround Instrument Planning, Instrument Failure Analysis, and Instrument Safety Training.