Scale and corrosion monitoring system using ultrasonic guided waves

A nondestructive method of monitoring scale buildup and corrosion in a section of pipe, the method comprising:

• transmitting, from a first transducer at a first location of the pipe, axisymmetric torsional ultrasonic guided waves (UGWs) to propagate along the pipe, the torsional UGWs spanning a frequency band comprising multiple higher order modes;
• receiving, by a second transducer at a second location of the pipe separated from the first location, the propagated torsional UGWs;
• transmitting, from a third transducer at a third location of the pipe, axisymmetric longitudinal UGWs to propagate along the pipe, the longitudinal UGWs spanning a frequency band comprising multiple higher order modes;
• receiving, by a fourth transducer at a fourth location of the pipe separated from the third location, the propagated longitudinal UGWs;
• and
• determining, by a processing circuit, a thickness of the scale buildup in the pipe and a thickness of the wall of the pipe using the received torsional UGWs and the received longitudinal UGWs, comprising:
• measuring attributes from the received torsional UGWs and the received longitudinal UGWs, the attributes being first arrival times or mode cutoff frequencies;
• comparing the measured attributes to sets of computed said attributes, each set representing a different combination of scale buildup thickness and pipe wall thickness;
• selecting the compared set of computed attributes that is closest to the measured attributes;
• and
• outputting the scale buildup thickness and the pipe wall thickness corresponding to the selected set for the section of pipe between the first and second locations.

A system for nondestructively monitoring scale buildup in a section of pipe, the system comprising:

• a first transducer configured to transmit axisymmetric torsional ultrasonic guided waves (UGWs) from a first location of the pipe, to propagate along the pipe, the torsional UGWs spanning a frequency band comprising multiple higher order modes;
• a second transducer configured to receive the propagated torsional UGWs at a second location of the pipe separated from the first location;
• and
• a processing circuit configured to determine a thickness of the scale buildup in the pipe between the first location and the second location using the received torsional UGWs by:
• measuring attributes from the received torsional UGWs, the attributes being first arrival times or mode cutoff frequencies;
• comparing the measured attributes to sets of computed said attributes, each set representing a different scale buildup thickness;
• selecting the compared set of computed attributes that is closest to the measured attributes;
• and
• outputting the scale buildup thickness corresponding to the selected set for the section of pipe between the first and second locations.

A system for nondestructively monitoring scale buildup and corrosion in a section of pipe, the system comprising:

• a first transducer configured to transmit axisymmetric torsional ultrasonic guided waves (UGWs) from a first location of the pipe, to propagate along the pipe, the torsional UGWs spanning a frequency band comprising multiple higher order modes;
• a second transducer configured to receive the propagated torsional UGWs at a second location of the pipe separated from the first location;
• a third transducer configured to transmit axisymmetric longitudinal UGWs from a third location of the pipe, to propagate along the pipe, the longitudinal UGWs spanning a frequency band comprising multiple higher order modes;
• a fourth transducer configured to receive the propagated longitudinal UGWs at a fourth location of the pipe separated from the third location;
• and
• a processing circuit configured to determine a thickness of the scale buildup in the pipe and a thickness of the wall of the pipe using the received torsional UGWs and the received longitudinal UGWs by:
• measuring attributes from the received torsional UGWs and the received longitudinal UGWs, the attributes being first arrival times or mode cutoff frequencies;
• comparing the measured attributes to sets of computed said attributes, each set representing a different combination of scale buildup thickness and pipe wall thickness;
• selecting the compared set of computed attributes that is closest to the measured attributes;
• and
• outputting the scale buildup thickness and the pipe wall thickness corresponding to the selected set for the section of pipe between the first and second locations.