Scanner Systems - Corrosion, Erosion, Crack and Thermal Monitoring of Boiler Walls and other High Temperature Plant

These high-accuracy systems have evolved from the well-established electrical resistance technique where thinning of a metal increases its measured electrical resistance. However, this measured resistance is also temperature dependent and the scanner has the ability to simultaneously measure temperatures (click here for our dedicated thermal systems) and resistances to a high precision, allowing this temperature dependency to be effectively nulled out.

Measurements are performed at, and between, adjacent sensor locations in a pre-defined sequence (i.e sensor arrays are 'scanned') to allow full surface maps to be produced. The scanners allow parameters such as metal loss, corrosion rate, remaining thickness and time-to-replacement to be automatically calculated and mapped.

Corrosion of Fireside Tubes (Left) and Resulting Fireside Tube Wall Corrosion Rate Map

A specialised version of the scanner technology was developed for use on Electric Power Research Institute (EPRI) sponsored projects in the USA for detecting crack growth on weld-overlaid boilers tubes. These systems have been installed on two supercritical power generation boilers in Pennsylvania and Texas.

The thermal monitoring hardware can operate independently of electrical resistance measurements to provide thermal mapping on a real time basis, either as surface temperatures or heat flux. Dedicated thermal monitoring systems are available, where plant integrity monitoring is not a requirement.

Fixed systems for long-term continuous monitoring (click for brochure). These have a central data logger and control unit, which can be positioned some distance from the monitoring area(s), and can handle up to four monitoring areas with a total of over 500 sensor locations. These systems were originally developed with the help of UK government funding in the 1990s. Fixed systems have been installed on both conventional and FBC boilers for the monitoring of corrosion and on two super-critical boilers in the USA, for the monitoring of crack growth on weld-overlaid boiler tubes in combination with mapping of the boiler walls’ thermal characteristics.

Portable systems for periodic monitoring (click for brochure). These have been developed for applications where a fixed system may not be the most appropriate or cost-effective means of monitoring. An example may be where there is a requirement for monitoring at a number of areas within a chemical complex or oil refinery. Sensors are permanently fixed at each monitoring location with associated cabling running back to a small local site box. This arrangement is suitable for hazardous areas, as power is only supplied when the portable components are connected, when conditions are safe to do so. There is no limit to the number of monitoring areas that may be monitored with a single set of portable equipment.

Scanners have many possible applications including boilers, incinerators, oil and gas pipelines and nuclear plant.

Direct, on-line monitoring of corrosion rates, metal loss and possible crack propagation
Direct, on-line monitoring/mapping of temperatures and heat flux (fixed systems)
Non-intrusive: no requirements for probes or probe insertion ports
Simple installation: for 2-D mapping, a matrix of simple connections is used
Maintenance free at (remote) monitoring locations
Increased confidence in plant operation and efficiency over extended time periods

Fixed or portable systems
Monitoring and mapping of corrosion/erosion, remaining thickness etc in high and low temperature environments
Real-time thermal mapping (fixed systems - dedicated thermal systems are available)
Can be integrated into plant monitoring systems
Robust yet sensitive instrumentation
Systems adaptable and expandable to suit individual requirements
Measures both short and long term trends
Well proven electrical resistance measurement technology

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		Scanner Systems - Corrosion, Erosion and Crack Monitoring
Boiler Wall Tube Metal Loss Scanner Cabinets - Supercritical Power Generation Boiler Fireside Boiler Wall Temperatures Circumferential Cracking - Supercritical Boiler Tubing Potential Field and Current Flow Lines around Simulated Crack Scanner Electrode Locations take a Variety of Forms		These high-accuracy systems have evolved from the well-established electrical resistance technique where thinning of a metal increases its measured electrical resistance. However, this measured resistance is also temperature dependent and the scanner has the ability to simultaneously measure temperatures (click here for our dedicated thermal systems) and resistances to a high precision, allowing this temperature dependency to be effectively nulled out. Measurements are performed at, and between, adjacent sensor locations in a pre-defined sequence (i.e sensor arrays are 'scanned') to allow full surface maps to be produced. The scanners allow parameters such as metal loss, corrosion rate, remaining thickness and time-to-replacement to be automatically calculated and mapped. Corrosion of Fireside Tubes (Left) and Resulting Fireside Tube Wall Corrosion Rate Map A specialised version of the scanner technology was developed for use on Electric Power Research Institute (EPRI) sponsored projects in the USA for detecting crack growth on weld-overlaid boilers tubes. These systems have been installed on two supercritical power generation boilers in Pennsylvania and Texas. The thermal monitoring hardware can operate independently of electrical resistance measurements to provide thermal mapping on a real time basis, either as surface temperatures or heat flux. Dedicated thermal monitoring systems are available, where plant integrity monitoring is not a requirement. The scanner systems take two forms: Fixed systems for long-term continuous monitoring (click for brochure). These have a central data logger and control unit, which can be positioned some distance from the monitoring area(s), and can handle up to four monitoring areas with a total of over 500 sensor locations. These systems were originally developed with the help of UK government funding in the 1990s. Fixed systems have been installed on both conventional and FBC boilers for the monitoring of corrosion and on two super-critical boilers in the USA, for the monitoring of crack growth on weld-overlaid boiler tubes in combination with mapping of the boiler walls’ thermal characteristics. Portable systems for periodic monitoring (click for brochure). These have been developed for applications where a fixed system may not be the most appropriate or cost-effective means of monitoring. An example may be where there is a requirement for monitoring at a number of areas within a chemical complex or oil refinery. Sensors are permanently fixed at each monitoring location with associated cabling running back to a small local site box. This arrangement is suitable for hazardous areas, as power is only supplied when the portable components are connected, when conditions are safe to do so. There is no limit to the number of monitoring areas that may be monitored with a single set of portable equipment. Scanners have many possible applications including boilers, incinerators, oil and gas pipelines and nuclear plant. Key Benefits Direct, on-line monitoring of corrosion rates, metal loss and possible crack propagation Direct, on-line monitoring/mapping of temperatures and heat flux (fixed systems) Non-intrusive: no requirements for probes or probe insertion ports Simple installation: for 2-D mapping, a matrix of simple connections is used Maintenance free at (remote) monitoring locations Increased confidence in plant operation and efficiency over extended time periods Key Features Fixed or portable systems Monitoring and mapping of corrosion/erosion, remaining thickness etc in high and low temperature environments Real-time thermal mapping (fixed systems - dedicated thermal systems are available) Can be integrated into plant monitoring systems Robust yet sensitive instrumentation Systems adaptable and expandable to suit individual requirements Measures both short and long term trends Well proven electrical resistance measurement technology Further Reading Fixed Scanner System Brochure (PDF File 1.4 MBytes) Portable Scanner System Brochure (PDF File 0.5 MBytes) Power Engineering International Scanner Article - May 2010 (PDF File 1.0 MBytes) On-Line Monitoring and Control of Furnace Wall Corrosion in PF-Fired Boilers D.M.Farrell, B.J.Robbins (RTL), P.Sikka, M.Seaman (Drax Power Ltd), Conference on High Temperature Plant and Life Extension, Cambridge 2004. (PDF File 3.0 MBytes) The Monitoring of Circumferential Fatigue Cracking of Furnace Tubes in Supercritical Boilers B.J. Robbins and D.M. Farrell (RTL), J. Stallings and S. Cardoso (EPRI), HIDA 5 Conference 2010 (PDF File 1.0 MBytes) Crack Growth Monitoring On Industrial Plant Using Established Electrical Resistance 'Scanner' Technology B.J.Robbins, D.M.Farrell (RTL), J. Stallings, S. Cardoso, W. Bakker (EPRI), NDT Conference 2008. (PDF File 1.1MBytes)