Sizing of Remnant Thickness in Pipes and Plates using Cut-off Properties by Widening Excitation Bands of Frequency and Wavelength

Technology: method for detecting a defect in a thickness in pipes and plates using cut-off properties ;

Industry & Application: Oil & Gas, Chemical Industry, NDE/NDT industries;

Market: The global waveguide market is projected to grow at a CAGR of 6.4% during the forecast period (2024-32).

Wall thinning is a major concern in petrochemical & aerospace industries, & corrosion & erosion are a few of main reasons.
Further, major drawbacks are observed in the range of detectable remnant wall thickness.
The main problem discussed in said invention, is how to provide a simplified method of non-destructive evaluation and structural health/integrity monitoring for efficiently determining remnant thickness of a structure/component.
Hence, said invention provides the solution in efficient manner.

Present patent disclosed a method for detecting a defect, in a thickness of an object, occurring due to corrosion and/or erosion.
The cut-off property is used to determine the remnant thickness of structures.
The cut-off thickness of a particular mode is the minimum thickness required for that mode to travel through the guided medium.
For a particular mode, at one specific frequency, the cut-off thickness is constant. When cut-off frequency increases cut-off thickness decreases.
The input excitation is coded to generate a mode in such a way that it contains a range of desired wavelengths & frequencies in it. The cut-off thickness acts as a filter allowing only the frequencies above the cut-off frequency to pass through.
The frequencies below the cut-off frequency undergo reflection to the original thickness & one cut-off frequency value is corresponding to one thickness reduction value. Cutoff frequency can be identified by measuring the lower frequency limit of the particular mode transmitted through the inspection area or by measuring the higher frequency limit reflected from the inspection area.

Facilitates a simplified method of non-destructive evaluation & structural health and integrity monitoring which precisely evaluates/determines remnant thickness of a structure/component in a single testing.
Provide an evaluating method in the areas where the remaining thickness of a structure/component needs to be precisely and quantitatively evaluated.
Implements excitation of a particular mode in a wide range of frequencies and uses cut-off property to determine the remnant thickness of structures.

Input Excitation:

The input excitation is coded in such a way that it contains a range of desired wavelengths and frequencies in it.
The range of wavelengths is achieved by varying the spacing between the excitation sources in comb transduction.
The range of frequencies is obtained using methods such as chirp excitation, spike excitation or low cycle Hanning pulse.

Utility:

Efficiently applicable in the oil & gas industries, NDE/NDT industries and others.

Prof. Krishnan Balasubramanian

Department of Mechanical Engineering

TRL-5

Technology validated in relevant environment

Technology Transfer