Measuring ovalisation of corrosion of cylindrical surfaces - by observing electrical signals initiated by fingers touching surface, useful for detecting ovalisation or corrosion of tubes

摘要

An appts. for measuring the precise form of a cylindrical surface comprises a number of fingers joined elastically to a central shaft and disposed at regular intervals around this shaft. The end position of each finger can be measured electrically, each finger being maintained in contact with the cylindrical surface being measured. The fingers can be put in the retracted position and the assembly can be moved along the tube. The electrical means of measurement the end position of each finger is connected to multiplexing and modulation components which are themselves connected to components for demodulation of the modulated signals connected to a recording mechanism by means of a discriminator. The appts. is for measuring the ovalisation or corrosion of the internal or external surfaces of tubes used e.g. in heat exchangers in nuclear reactors and in pipelines in petroleum workings, where the measurement are often made in noxious atmospheres or in places difficult of access. The signals are easily transmitted to the outside.