One approach to detecting corrosion under insulation is to look for moisture. The Hydrotector is designed for rapid determination of water content in insulation on pipes and vessels.
The unit is battery powered and provides a direct readout of moisture content in engineering units. All surveys are stored with readings identified by vessel or pipe and location.
Designed as a screening tool the Hydrotector works well with corrosion measurement techniques by identifying locations where corrosion is likely.
Moisture detection is by the neutron backscatter technique and the unit includes a small, radioactive isotope. The nature of operation means the source is constantly supervised and there is no need for a fixed barricade as for conventional radiography.
Measurements are based on neutron scatter by hydrogen in the water. Other materials also contain hydrogen so the system needs to be set up for a particular insulation system. The procedure is to take readings from reference samples and store them in memory. This allows the operator to determine the location of unacceptable moisture levels.