Event Title

Special Sensors for Generating Lamb Waves in Pipes

Location

Snowbird, UT, USA

Start Date

1-1-1999 12:00 AM

Description

The pipeline is a strategically important technology to any modern nation. It is used for transporting water, sewage, natural gas, crude oil, refined petroleum products, hazardous chemicals, grain and hundreds of other products. Pipeline assessment is often expensive and disruptive. Efficient inspection of pipelines for internal damages is a challenging task. It becomes even harder when pipes are coated with insulating materials. Under traditional ultrasonic methods insulation coatings are removed at selected places. Then wall thickness at those spots are measured by ultrasonic transducers. Sudden drop in the pipe wall thickness indicates possibility of corrosion damage. This is a time-consuming and expensive operation. The Lamb wave inspection technique, proposed in this paper, is a much more efficient technique because by this technique long pipes can be inspected by removing the insulation coating at a relatively fewer locations. In this technique the Lamb wave propagates along the length of the pipe, this is also known as cylindrical guided waves. For efficient generation of Lamb modes in the pipe wall special sensors are to be fabricated. Several arrangements of transmitter, receiver and specimen have been tried out. Some arrangements require the presence of a coupling fluid between the transducer and the pipe wall. These arrangements can be used for inspecting horizontal pipes only. Other arrangements do not need any coupling fluid and can be used equally well for inspecting horizontal, inclined, and vertical pipes. Experimental results, presented in this paper, show that for efficient inspection of a pipe it should be excited by multiple transducers. Transducers should be positioned at an inclination relative to the pipe axis.

Book Title

Review of Progress in Quantitative Nondestructive Evaluation

Volume

18A

Chapter

Chapter 4: UT Transducers and Fields, Sensors

Section

NDE Sensors

Pages

1155-1162

DOI

10.1007/978-1-4615-4791-4_147

Language

en

File Format

application/pdf

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Jan 1st, 12:00 AM

Special Sensors for Generating Lamb Waves in Pipes

Snowbird, UT, USA

The pipeline is a strategically important technology to any modern nation. It is used for transporting water, sewage, natural gas, crude oil, refined petroleum products, hazardous chemicals, grain and hundreds of other products. Pipeline assessment is often expensive and disruptive. Efficient inspection of pipelines for internal damages is a challenging task. It becomes even harder when pipes are coated with insulating materials. Under traditional ultrasonic methods insulation coatings are removed at selected places. Then wall thickness at those spots are measured by ultrasonic transducers. Sudden drop in the pipe wall thickness indicates possibility of corrosion damage. This is a time-consuming and expensive operation. The Lamb wave inspection technique, proposed in this paper, is a much more efficient technique because by this technique long pipes can be inspected by removing the insulation coating at a relatively fewer locations. In this technique the Lamb wave propagates along the length of the pipe, this is also known as cylindrical guided waves. For efficient generation of Lamb modes in the pipe wall special sensors are to be fabricated. Several arrangements of transmitter, receiver and specimen have been tried out. Some arrangements require the presence of a coupling fluid between the transducer and the pipe wall. These arrangements can be used for inspecting horizontal pipes only. Other arrangements do not need any coupling fluid and can be used equally well for inspecting horizontal, inclined, and vertical pipes. Experimental results, presented in this paper, show that for efficient inspection of a pipe it should be excited by multiple transducers. Transducers should be positioned at an inclination relative to the pipe axis.