Plugged Taps and Impulse Lines are no Longer an Issue for Pressure and Differential Pressure Transmitters in Dirty Applications

Presented By

Stan Miller - Clearguard

Conference: Galveston 2016

Every automated industrial process, requires accurate, reliable, continual measurement. The most common method of level and flow measurement is by differential pressure transmitters, (Dp Cells) however, these can be hampered by partial plugging of tapping points and impulse lines. Many processes have services, where the operators know that they cannot rely on the instruments. There are also many other safety critical services. Scale, soot, or crystals build up in the bore of the tapping point over a period of time, this gradually affects the process variable measurement to a point where field instrument data is inaccurate.
The industry standard method of removing this scale is known as rodding out or Blowing out and is typically carried out manually, under permit, once the hole is completely blocked. This exposes a maintenance or process operator, to (often live) process and the obvious HAZOP risks, resulting in the need for strict PPE and onerous safe working procedures. Incorrect Field Instrument installation and purge application have also resulted in false data transmitted from the Dp Cell.
By frequently stroking a scraper through the bore of a tapping point before debris begins to form, you will reduce the potential of blocked tapping’s and unreliable field instrument data. This eliminates the need for obtrusive and potentially unsafe maintenance rodding/blowing out practices, increased purge consumption, dual, triple and quadruple redundancies, oversized tapping points and lack of confidence in data from the field instrument. Rather than use non-contact instruments to treat the symptom, our presentation will focus on reducing the HAZOP risks to personnel, and improving plant process accuracy using proven, reliable, robust and sophisticated Dp Cells and Pressure Transmitters.This presentation will detail:-Functional safety of differential pressure measurement, including compliance with recommended installation specifications and codes.
Historic examples of incidents directly relating to flawed pressure measurement. Risks in unreliable process variable measurements, manual rodding/blowing out and inefficient unit operation. Alternative methods to keep tapping points clear ensuring functional safety, using proven Autorodding technology. Improvement in legacy pressure measurement systems, design and procedures. Ensuring no induced errors are created and dilution is at an absolute minimum. Actual field results where accurate process variable measurement has led to improved site incident figures and unit process throughput. Importance of ensuring correctly installed field instruments provide the accurate data allowing for improved unit efficiencies, eliminate shutdowns and operating “blind” and saving $$$.

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