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51317--9595-Application of Permasense Real-time Ultrasonic Thickness Monitoring at The Geysers

An automated remote ultrasonic thickness (UT) monitoring system using dry-coupled waveguide ultrasonic transducers at The Geysers. Dry-coupled waveguide UT transducers can provide remote real-time measurement of wall thicknesses on high temperature process piping. 

 

Product Number: 51317--9595-SG
ISBN: 9595 2017 CP
Author: John Farison
Publication Date: 2017
Industry: Energy Generation
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This paper presents a case study of Permasense ultrasonic thickness (UT) sensors and monitoring software installed at The Geysers Geothermal Field. The Permasense sensors and software were installed on steam wellhead tie-in piping in a remote area of the Geysers field to monitor steam piping thicknesses downstream of a corrosion mitigation steam scrubbing system. The Permasense system provides online time graphs of wall thicknesses and early warning that our scrubbing system was not completely mitigating the corrosion rate. The process piping and steam scrubbing equipment were modified and the Permasense UT system confirms that our process modifications were successful.Geothermal steam and hot water piping networks are very extensive and are typically constructed primarily of carbon steel. Geothermal fluids can be very corrosive and undetected internal corrosion can lead to through-wall leaks or even ruptures. Routine periodic ultrasonic thickness (UT) measurements of piping wall thicknesses are therefore required for safety to assuring integrity of pressure piping. Operating wall temperatures under insulation can range from 250 to 450 deg F or higher. UT sensors rapidly degrade when used repeatedly on hot piping and 3-6 month service life for a sensor used for daily spot readings is typical. Removal and reinstallation of insulation is required for each set of UT manual readings.Permasense UT sensors can provide real-time remote measurement of wall thicknesses on hot process piping without the labor intensive removal and reinstallation of insulation. UT readings are taken on a user defined schedule over a network DSL connection and stored in a database. Time graphs of UT data are automatically created by the Permasense software to see wall thickness trends and corrosion rates.Corrosion rates in carbon steel can exceed 1000 mils per year (mpy) in areas with high HCl content steam and acid-dewpoint corrosion. Continuous steam scrubbing of steam from certain wells with sodium hydroxide solutions is required to neutralize the HCl content in steam. The scrubbed steam is rendered non corrosive to miles of carbon steel steam piping downstream. Proving that wall thicknesses are being protected is the measure of success for the scrubbing system. The Permasense UT sensors gave early warning of process upsets and ongoing high corrosion rates without waiting for a hole to develop. This allowed us to redesign our scrubbing system to get better contacting of scrub solution with steam and then test the results.

This paper presents a case study of Permasense ultrasonic thickness (UT) sensors and monitoring software installed at The Geysers Geothermal Field. The Permasense sensors and software were installed on steam wellhead tie-in piping in a remote area of the Geysers field to monitor steam piping thicknesses downstream of a corrosion mitigation steam scrubbing system. The Permasense system provides online time graphs of wall thicknesses and early warning that our scrubbing system was not completely mitigating the corrosion rate. The process piping and steam scrubbing equipment were modified and the Permasense UT system confirms that our process modifications were successful.Geothermal steam and hot water piping networks are very extensive and are typically constructed primarily of carbon steel. Geothermal fluids can be very corrosive and undetected internal corrosion can lead to through-wall leaks or even ruptures. Routine periodic ultrasonic thickness (UT) measurements of piping wall thicknesses are therefore required for safety to assuring integrity of pressure piping. Operating wall temperatures under insulation can range from 250 to 450 deg F or higher. UT sensors rapidly degrade when used repeatedly on hot piping and 3-6 month service life for a sensor used for daily spot readings is typical. Removal and reinstallation of insulation is required for each set of UT manual readings.Permasense UT sensors can provide real-time remote measurement of wall thicknesses on hot process piping without the labor intensive removal and reinstallation of insulation. UT readings are taken on a user defined schedule over a network DSL connection and stored in a database. Time graphs of UT data are automatically created by the Permasense software to see wall thickness trends and corrosion rates.Corrosion rates in carbon steel can exceed 1000 mils per year (mpy) in areas with high HCl content steam and acid-dewpoint corrosion. Continuous steam scrubbing of steam from certain wells with sodium hydroxide solutions is required to neutralize the HCl content in steam. The scrubbed steam is rendered non corrosive to miles of carbon steel steam piping downstream. Proving that wall thicknesses are being protected is the measure of success for the scrubbing system. The Permasense UT sensors gave early warning of process upsets and ongoing high corrosion rates without waiting for a hole to develop. This allowed us to redesign our scrubbing system to get better contacting of scrub solution with steam and then test the results.

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