Online Corrosion Monitor
Suitable for Monitoring General, Galvanic, and Crevice Corrosion, Flow-Accelerated Corrosion, and Cavitation
Corrosion Monitor with a high sensitivity, which allows for direct and rapid on-line measurement of corrosion, flow accelerated corrosion (FAC), and cavitation rates and correlation of corrosion with operating conditions (flow, % moisture, chemistry).  Suitable for pipe IDs and ODs, vessels, soil corrosivity, etc.
Background
In many applications, corrosion of piping components occurs during operation and is difficult to detect except by inspections, coupon removal, or non-destructive testing during outages.  One available option is to install a corrosimeter to monitor corrosion during operation using electrical resistance probes.  These commercially available probes are made from round wire or bar that is bent into a U-shape.  The probe is inserted into a pipe and protrudes out into the flow of water, so the measured corrosion rate is for the bulk fluid, which can be significantly different than the corrosion rate at the surface of the pipe.
The Jonas, Inc. On-line Corrosion Monitor is based on special surface mounted probes developed by Jonas, Inc. as a part of the Department of Defense Small Business Innovative Research project, “Smart Water Piping Corrosion and Scale Monitor” and is capable of measuring the corrosion, FAC, and cavitation rates at the ID and OD surfaces of pipes and other components using the electrical resistance of the sensors.  The electrical resistance method uses a precise measurement of the change of resistance of the metal sensor.  As the cross-sectional area is reduced, its resistance is increased.  The change in resistance is related to the corrosion rate.
Description
The Corrosion Monitor consists of a Probe with Electrical Resistance Sensor(s) which is either surface mounted or inserted into the process pipe bulk flow through a flanged or threaded connection (Figure 1).  When the sensor is placed in a straight piece of pipe, the Monitor (Processing Unit) will measure the corrosion rate at the surface of the pipe.  When installed downstream of a flow disturbance (weld backing ring, elbow, tee, etc.), the flow-accelerated corrosion or cavitation rate will be measured.  For applications where FAC is possible but it is impractical to install the sensor near a flow disturbance, a turbulator can be installed on the sensor to simulate the turbulence that can lead to FAC.  
The Electrical Resistance Sensors of the Probe are periodically or continuously connected to a Monitor with a digital multimeter data acquisition card installed in a Computer.  The Computer controls the data acquisition card using custom software that calculates the corrosion rate at prescribed intervals for continuous monitoring or periodically when connected to the probe.  The Monitor plots the corrosion rate versus time, Sensor (specimen) thickness versus time, and selected operating parameters.  It can store up to one year of data and print graphs and reports.
Schematic of On-line Corrosion Monitor for Pipe ID
Figure 1:  Schematic of On-Line Corrosion Monitor for Pipe ID
Options
Multiple sensors
Multiple monitoring locations
Additional condensation sensor
Additional surface conductivity sensor
Cavitation noise
Turbulator for simulating FAC flow conditions
Wireless data transmission
Specifications
Maximum Temperature:  450 F (232 C)
Maximum Pressure:  450 psia (3.1 MPa) and higher
Corrosion Rates:  Max.  1000 mils/yr; Min. 0.01 mils/yr
Sensors per Monitor:  32
Data Storage:  1 year - graphs and reports
Required Electrical Power:  480 W normal (720 W peak)
Required Ordering Information
Type of Monitoring:  general corrosion, FAC, crevice corrosion, galvanic corrosion,  cavitation
Location of Sensors:  ID, OD, soil, water, other, etc.
Fluid Composition
Fluid Flow Velocity or Mass Flow Rate
Fluid Temperature
Fluid Pressure
Pipe Material and Test Material
Pipe Size (OD, wall thickness)
Number of monitoring locations
Location for Monitor Installation (within 30 ft of monitoring location)
NEMA Requirements for Monitor/Computer
Data Transmission:  None, 0-5 Volts, 4-20 mA, wireless
Availability of Electrical Connection/Voltage