MAY-JUN 2019

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Part 3 38 INTECH MAY/JUNE 2019 WWW.ISA.ORG SPECIAL SECTION and failures. The "big data" collected from the instruments can be used for making decisions about when main - tenance is actually needed. Hence, 70 percent or more of conventional PM tasks for both process instrumenta - tion and equipment could be deleted. Digital transformation will address the major maintenance challenges of aging equipment and the aging work - force, and can highly cut cost, time, and manpower. optimization opportunities and life- cycle costs, and capturing and apply- ing lessons learned across the plant or company. Impact on instrumentation preventive maintenance Digital transformation will change the world of preventive maintenance for instrumentation and equipment to more "predictive analytics," where data is used to predict performance in industry references (figure 3). Doing analysis requires the PM ex- ecuter to write accurate PM findings. The analysis of the compiled find- ings helps identify the PM tasks that add value and eliminate the "value- wasting" PM tasks. Also, it helps to identify repeated failures and to rec- ommend revisiting some system de- signs. Moreover, analyzing PM find- ings helps improve PM tasks by better managing spare parts, highlighting Instrument description PM task performer Online/ turnaround PM interval Task description Vibration measuring devices/switches Maintenance Online • Visually inspect damage, corrosion, cables and connection, enclosure tightness. • For switches, portable vibration measurement tool can be used to verify the installed switch reading. • For vibration circuits with dual voting (2 out of 2), PM shall be conducted during turnaround. • For vibration circuits with no-voting (1 out of 1), the following needs to be performed every year: - Check grounding. - Check extension cable and connector for scratches or damage. • Confirm DC voltage at proximate without probe. • Check vibration probe and extension cable resistance. • Clean dirt and grease from the connector by spraying it with an electrical contact cleaner. • Check diagnostics via online asset condition monitoring system/station). Level gauges Operation Online As needed • Sight glass: - Retorque overhauled sight glass after plant startup. - Drain and flush. - Check for any leakage and examine for glass cracks. • Magnetic level indicator: - Drain to confirm float is not stuck. Maintenance Turnaround • Ensure all isolation and vent/drain valves are functional and not clogged. Replace as needed. Thermowells Maintenance Turnaround • Remove and inspect thermowells for corrosion or cracks. Pressure gauges Operation Online As needed • Check the zero-reading of pressure gauges by isolating and draining/venting. Also, compare the pressure gauge reading to a pressure transmitter or pressure gauge next to it. Pressure gauges can be calibrated during plant shutdown. Process flowmeters Maintenance Online Yearly • PM task for differential pressure flowmeters: - Inspect orifice in question during turnaround. - Check for leaks and check zero. - Check reading using clamp-on flowmeter. • PM task for inline flowmeters (like ultrasonic, Coriolis, vortex, and magnetic flowmeters): - Conduct zero, if possible, by isolating the flowmeter while it is full of liquid. - Conduct electronic verification or check diagnostics to verify performance and reading accuracy. Obtain details from the manufacturer. - Use clamp-on flowmeter to cross-check the reading. Flare flowmeter Operation/ maintenance Online Yearly • Use smart sensor analytics (online diagnostics) or compare to a reference (inser- tion flowmeter, tracer). • Or collect a gas sample and identify the composition and then calculate sound velocity using the manufacturer software and compare to the flowmeter reading. (This option is for ultrasonic flowmeters only.) Recommended preventive maintenance for process instrumentation

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