Systems and methods of detecting pipe defects
Inventors
Federici, John F. • Rizzo, Louis • Gatley, Ian • Gatley, Samuel • Maillia, Joseph
Assignees
Northeast Gas Association • New Jersey Institute of Technology
Publication Number
US-11709139-B2
Publication Date
2023-07-25
Expiration Date
2041-06-22
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Abstract
An example system for detecting pipe defects is provided. The system includes a transmitter, a receiver and a processing device. The transmitter is oriented to transmit Terahertz (THz) waveform pulses towards at least one of an outer surface of a pipe or an inner surface of the pipe. The receiver is oriented to receive reflected Terahertz (THz) waveform pulses from at least one of the outer surface of the pipe or the inner surface of the pipe. The processing device configured is to receive as input the Terahertz (THz) waveform pulses transmitted from the transmitter and the reflected Terahertz (THz) waveform pulses received by the receiver and, based on the received input, determine if a defect in the pipe exists.
Core Innovation
The invention provides systems and methods for non-destructive evaluation (NDE) of pipe defects, particularly in polyethylene (PE) pipes joined by butt weld fusion. It comprises a transmitter to emit Terahertz (THz) waveform pulses and a receiver to capture the reflected pulses from pipe surfaces or joints. A processing device analyzes the transmitted and reflected THz pulses to determine if defects, such as contaminants, improper pressure fusion, or cold fusion joints, are present.
The background identifies a significant problem in the gas industry: defects in butt fusion-welded PE pipes are difficult or nearly impossible to detect, which can lead to hazardous gas leaks and reduce the service lifetime of pipe joints. Issues such as contaminants, improper fusion pressure, and cold fusion create latent defects not readily observable by conventional methods.
The core innovation leverages THz spectroscopy and imaging to detect pipe joint integrity issues, including surface and subsurface defects and stress-induced birefringence changes. The system may use a variety of configurations, including perpendicular and angled orientations, rotatable polarizing filters, beamsplitters, prisms with matching refractive index substances, and stress mapping through photoelastic measurements, enabling testing both before and after field installation.
Claims Coverage
There are three independent claims covering the main inventive features of the system, method, and computer-readable medium for detecting stress-induced pipe defects using Terahertz (THz) waveform pulses and polarization measurements.
System for detecting stress-induced pipe defects using polarized Terahertz (THz) waveform pulses
The system includes: - A transmitter oriented to transmit THz waveform pulses towards the outer or inner surface of a pipe. - A receiver oriented to receive reflected THz waveform pulses from the pipe surfaces. - A first polarizing filter disposed adjacent to the transmitter through which THz pulses are transmitted. - A second polarizing filter disposed adjacent to the receiver through which reflected THz pulses pass before detection. - A processing device configured to receive both parallel and perpendicular polarization measurements from the receiver (relative to the pipe’s central longitudinal axis), determine the equality or difference of the measurements, and thus determine the existence or absence of intrinsic stress-induced pipe defects.
Method of detecting stress-induced pipe defects using polarized THz waveform pulses
The method involves: 1. Transmitting THz waveform pulses through a first polarizing filter towards a pipe surface. 2. Receiving reflected THz pulses through a second polarizing filter. 3. At a processing device, acquiring parallel and perpendicular polarization measurements (relative to a central longitudinal axis of the pipe). 4. Determining whether an intrinsic stress-induced defect exists by comparing the two polarization measurements (equality indicates no defect; difference indicates a defect).
Computer-readable medium for detecting stress-induced pipe defects with THz waveform pulses and polarization measurement
This aspect covers a non-transitory computer-readable medium storing instructions which, when executed by a processing device, cause the processing device to: - Transmit THz waveform pulses with a transmitter through a first polarizing filter. - Receive reflected THz pulses with a receiver through a second polarizing filter. - Receive, as input, both parallel and perpendicular polarization measurements. - Determine the presence or absence of intrinsic stress-induced pipe defects based on the equality or inequality of the polarization measurements.
In summary, the inventive features focus on detecting stress-induced pipe defects using emitted and reflected polarized Terahertz waveform pulses, leveraging parallel and perpendicular polarization measurements to determine stress in pipes. The invention is realized as a system, a method, and as software instructions embodied on a computer-readable medium.
Stated Advantages
Enables non-destructive evaluation for detection of defects in polyethylene (PE) pipes and butt weld fusion joints.
Allows detection of pipe defects immediately after welding and before installation, reducing the need for expensive repairs due to gas leaks.
Capable of detecting various defects including contaminants, over pressure, under pressure, and cold fusion joints.
Utilizes THz imaging and spectroscopy to achieve higher resolution detection of small defects as compared to ultrasound.
Provides more sensitivity than x-rays in differentiating plastics or plastic layers due to THz-range refractive index variation.
Can generate stress maps for pipes using photoelastic (birefringence) measurements, aiding in the identification of residual and intrinsic stress.
Uses low THz power levels, allowing safe usage without special radiation handling training.
Enables quality control verification of internal stresses in pipes prior to fusion, minimizing resulting stress in joints.
Documented Applications
Detection of surface and subsurface defects in polyethylene pipes used for underground gas industry applications.
Quality control verification of pipe joints immediately after welding, prior to field installation.
Post-installation testing of pipes in the field for detection of defects or stresses in butt fusion joints.
Measurement and imaging of intrinsic and residual stresses in pipes and pipe joints via THz birefringence analysis.
Assisting in the selection of pipe sections with matching internal stresses prior to butt weld fusion to reduce stresses in joints.
Detection and imaging of contaminants, air gaps, sand, oil, metal, and other foreign materials in the weld region or pipe.
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