Defects In Pipes Research Articles

DESTRUCTION OF LARGE-DIAMETER STEEL PIPES AT ROLLED BURNTON DEFECT

In the domestic pipelines the large-diameter pipes of different methods of manufacturing are used − the straight-line-seam welded pipes, the one- and double-seam welded pipes and the spiral-seam welded pipes. The diameters of pipes are up to 1420 mm, the strength class of pipes is up to K65 per the API standard. The world’s latest innovative technologies for the production of the large-diameter straight-line-seam single-joint welded pipes (the diameters are 1020 mm, 1220 mm and 1420 mm, the grade strengths of steel are K38 − K65 and X42 − X80, the wall thickness is up to 52 mm, the length is up to 18 m and the working pressure is up to 22.15 MPa) are the processes developed by the German company SMS Meer and based on the step-by-step process of press forming according to the scheme JCOE. The SMS Meer technologies are widely used by the Russian pipe plants − JSC “Vyksa Steel Works”, JSC “Izhora Pipe Mill”, PJSC “Chelyabinsk Pipe-Rolling Plant”, as well as the plants in Germany, China and India. However, the accident statistics of Russian pipelines shows that the stress corrosion of metal of the pipe’s wall occurs mainly on the pipelines with the large diameter 700 − 1420 mm. With more than 80 % of the destruction of pipelines with the signs of stress corrosion are observed on the pipelines with the diameters of 1020 – 1420 mm. The main cause of the corrosion-mechanical cracking of metal of pipe’s wall is the combined effect of three factors: 1) low steel-smelting quality of metal and the manufacturing defects of pipes (the large residual stresses, the microcracks and microexfoliation of metal after the pipe blanks’ forming, the corrugation and hairlines defects, the rolled burnt-on defects, the faulty fusion of weld seam and so on); 2) presence of corrosive-active environment and its access to the metal surface; 3) high-cycle fatigue and fracture of metal due to the pulsations of the in-tube working pressures and hydroblows. On the domestic pipelines pipes’ ruptures are almost two times more frequent than in the United States and Europe due to the manufacturing defects and the construction-installation defects. Therefore, it is necessary to study carefully the causes of the known cases of pipelines’ rupture due to the manufacturing defects. In this work, the pipe with the rolled burnt-on and the hairline defect on the outer surface of pipe is considered. The mathematical criterion for determining the critical in-tube pressure at which the elastic-plastic rupture of the pipe’s wall is taken place is obtained. The results of the investigation can be used in the diagnostics of the rupture’s causes of the steel major- and medium-diameter pipes on the main and interfield pipelines.

Augmented reality application for training in pipe defects ultrasonic investigation

The paper presents the development process of an Augmented Reality (AR) application used for training operators in using ultrasonic equipment for non-destructive testing (NDT) of pipework. The application provides workers useful information regarding the process steps, the main components of ultrasonic equipment and the proper modality of placing, aligning and moving it on pipe and weld. Using tablet or mobile phone device, an operator can see on screen written details and images on standardized working method, thus offering assistance during the training process. Allowing 3D augmented visualization of ultrasonic equipment overlaid on the real-world environment consisting in pipes and welds, the AR application makes the NDT process easier to understand and learn, as the initial evaluation results showed.

Suggestion of the Domestic CCTV Inspection Sewer Pipe Defect Codeby Sewer Defect Frequency Analysis

Suggestion of the Domestic CCTV Inspection Sewer Pipe Defect Codeby Sewer Defect Frequency Analysis

Sizing of defects in special shaped coolant pipe of Tokamak magnet based on eddy current testing signals

In this study, quantitative evaluation of defects in an outer-square-inner-round (OSIR), aluminum pipe, which is used as the coolant pipe of Tokamak superconducting magnet, is conducted based on the eddy current testing (ECT) technique. First, numerical simulations to predict ECT signal due to defe cts in OSIR pipes are performed using a code of Ar method; Second, ECT signal is detected using an Eddyfi ECT instrument with an absolute pancake ECT probe; Finally, the defect profile in OSIR pipe is reconstructed from the experimental ECT signals with the help of a fast-forward ECT solver, the developed multiple databases strategy and the deterministic inversion algorithm.

Flux-focusing eddy current sensor with magnetic saturation for detection of water pipe defects

Flux-focusing eddy current sensor with magnetic saturation for detection of water pipe defects

Probability of rupture model for corroded pipelines

A log-logistic model is developed to predict the probability of rupture (POR) given burst of a pressurized steel pipeline at a naturally-occurring part-through wall corrosion defect. The predictors of the model are the defect depth normalized by the pipe wall thickness and defect length normalized by the square root of the product of the pipe diameter and wall thickness. A set of 140 full-scale burst tests of corroded thin-walled pipes are collected from the open literature to calibrate and validate the proposed POR model. The parameters of the POR model are evaluated using the maximum likelihood method. To facilitate deterministic defect assessments, a threshold POR of 0.35 is proposed such that defects with POR greater than or equal to 0.35 are designated as potential ruptures. The impact on the proposed POR model due to the measurement errors associated with defect sizes reported by the inspection tool is examined through sensitivity analyses.

Approach for removing ghost-images in remote field eddy current testing of ferromagnetic pipes.

In the non-destructive testing of ferromagnetic pipes based on remote field eddy currents, an array of sensing coils is often used to detect local defects. While testing, the image that is obtained by sensing coils exhibits a ghost-image, which originates from both the transmitter and sensing coils passing over the same defects in pipes. Ghost-images are caused by transmitters and lead to undesirable assessments of defects. In order to remove ghost-images, two pickup coils are coaxially set to each other in remote field. Due to the time delay between differential signals tested by the two pickup coils, a Wiener deconvolution filter is used to identify the artificial peaks that lead to ghost-images. Because the sensing coils and two pickup coils all receive the same signal from one transmitter, they all contain the same artificial peaks. By subtracting the artificial peak values obtained by the two pickup coils from the imaging data, the ghost-image caused by the transmitter is eliminated. Finally, a relatively highly accurate image of local defects is obtained by these sensing coils. With proposed method, there is no need to subtract the average value of the sensing coils, and it is sensitive to ringed defects.

Modeling the scattering of elastic waves from defects in buried pipes

Long Range Ultrasonic Testing (LRUT) is a popular non-destructive evaluation technique for identifying defects in pipelines. The method sends an elastic wave down the walls of a pipe and then monitors echoes that arise if the wave is scattered by a defect. The technical challenge of LRUT lies in separating out, and interpreting from coherent and random background noise, those signals that belong to a defect. This becomes particularly challenging when a pipe is buried, because energy in an elastic wave is known to leak out of the pipe walls when it is surrounded by materials such as soil, concrete, or sand. To address this problem it is necessary to develop a better understanding of how elastic waves propagate in buried structures, and so, a finite element based model is introduced here that seeks to analyze the scattering from a defect in a buried pipe in both the frequency and time domain. Results from the implementation of this numerical model for the torsional T(0,1) mode are presented, and the effects of the burying material on the LRUT time domain response are discussed.

첩릿변환을 이용한 배관 축방향 결함검출

첩릿변환을 이용한 배관 축방향 결함검출

Sewer pipe defects diagnosis assessment using multivariate analysis on CCTV video imagery

Closed circuit television (CCTV) technology has been commonly used to inspect underground pipe defects, and high CCTV image quality is a prerequisite for accurate defect diagnosis. An acceptance criterion for CCTV inspection videos is critical for ensuring accurate diagnosis and preventing disputes between employers and contractors. This paper used multivariate statistical methods to evaluate the overall quality of CCTV images and to define an acceptance criterion for CCTV videos. Numerous CCTV images from a sewer inspection project were assessed and their quality, consisting of similarity in luminance and contrast distortions, was calculated by comparing a set of ideal images. Principal component analysis (PCA) and redundancy analysis (RDA) grouped the CCTV videos into homogeneous segments with similar image quality and provided a visual acceptance criterion for CCTV inspection videos. Furthermore, RDA triplot indicated that the contrast improvement of CCTV images can effectively enhance image quality and increase the diagnosis efficiency.

Ovalization Defect in Energy Pipes Caused by Concentrated Load

Steel pipes are used to build pipelines that carry gas and oil across a country or a continent. The majority of onshore pipelines run underground; hence, they are called buried pipelines. These buried pipelines must endure external interferences and complex loading that result from geotechnical causes, aggressive environments, and operational requirements. Many segments of an underground pipeline may rest on rock tips and other localized hard surfaces, resulting in concentrated reaction load acting on small area of the outer wall of the operating pipeline. As a result, permanent inward deformations in the pipe wall, known as dent defect, can form. In addition, a resulting cross-sectional irregularity, known as an ovalization defect, can also occur. Pipe ovalization defects are a concern of pipeline operating companies, as the defect may challenge a pipeline's operation and/or structural integrity and safety. This research was completed by the Centre of Engineering Research in Pipelines located at the University of Windsor to examine the effects that rock tip shape, operating (internal) pressure, and a pipe's diameter-to-thickness ratio (D/t) have on an NPS30 X70-grade pipe's ovalization defect when it is subjected to such a concentrated load. This article discusses the lab-based full-scale examinations, finite element analysis (FEA) simulations, results, and discussions.

Defect detection of pipes using Lyapunov dimension of Duffing oscillator based on ultrasonic guided waves

This study proposes a novel small defect detection approach for steel pipes using the Lyapunov dimension (D) of the Duffing chaotic system based on ultrasonic guided waves. In this paper, inspection model is constructed by inputting the measured guided wave signal into the Duffing equation as the external turbulent driving force term and thenDis calculated. The properties of the Duffing system's noise immunity are first demonstrated theoretically based on the Lyapunov exponents. By comparingDof the Duffing inspection system between the conditions of the inputted pure noise and the guided wave signal, the amplitude of the periodic force (F), the important parameter of the Duffing inspection system, could be determined. The values of other parameters of the Duffing inspection system are subsequently determined according to the numerical investigation. Furthermore, a time-moving window function is constructed to scan along the measured signal to locate the defect. And the small defect echo signal polluted by the noise is illustrated to prove the availability of the proposed method. Both numerical and experimental results show that the proposed approach can be used to improve the sensitivity of small defect detection and locate the small defect in pipes.

Analysis of shape and location effects of closely spaced metal loss defects in pressurised pipes

Metal loss due to corrosion is a serious threat to the integrity of pressurised oil and gas transmission pipes. Pipe metal loss defects are found in either single form or in groups (clusters). One of the critical situations arises when two or more defects are spaced close enough to act as a single lengthier defect with respect to the axial direction, causing pipe ruptures rather than leaks, and impacting on the pressure containing capacity of a pipe. There have been few studies conducted to determine the distance needed for defects to interact leading to a failure pressure lower than that when the defects are treated as single defects and not interacting. Despite such efforts, there is no universally agreed defect interaction rule and pipe operators around the world have various rules to pick and choose from. In this work, the effects of defect shape and location on closely spaced defects are analysed using finite element analysis. The numerical results showed that defect shapes and locations have a great influence on the peak stress and its location as well as the failure pressure of pipes containing interacting defects.

Pressurized line pipe wall thinning detection using a distributed fiber-optic sensing system

Wall thinning defects in steel pipes are usually localized and are difficult to detect using traditional sensors that have a small coverage and limited measuring range. A distributed fiber sensor, based on the Brillouin backscattering sensing system, has been demonstrated to be able to measure the strain and detect the defect in a pipe accurately. A 1.8 m pipe segment that contains artificial thinning from 13 to 60% of wall thickness at various positions was subjected to an internal pressure of 350 kgf/cm2. Hoop strain distribution along the whole pipe segment was monitored by a single optical fiber. The measured strains compared favorably with strain gauge results. The method proposed in this study shows promising results for the detection of the existence and location of wall thinning defects in long distance pressurized pipe.

A qualitative analysis of early defects present in PVC-U sewers but not observed in rigid pipes

The objective of the study was to analyze early defects in PVC-U sewer pipes that are not observed in rigid pipes. Field investigations were conducted on newly laid PVC-U sewer pipes in more than a dozen cities in Poland using CCTV equipment and a special device for measuring deflections. The analysis focused on qualitative data concerning defects observed in PVC-U sewers. Three types of defects, i.e. dents, deflections and buckling, were thoroughly analyzed to determine whether trenchless rehabilitation of such pipes is possible and to improve the existing sewer deterioration models. The major conclusions concern the types, sizes and frequencies of defects in PVC-U pipes, their causes, and the possibility of future rehabilitation as well as the improvement in the deterioration models.

Giant Magnetoresistance Sensors: A Review on Structures and Non-Destructive Eddy Current Testing Applications.

Non-destructive eddy current testing (ECT) is widely used to examine structural defects in ferromagnetic pipe in the oil and gas industry. Implementation of giant magnetoresistance (GMR) sensors as magnetic field sensors to detect the changes of magnetic field continuity have increased the sensitivity of eddy current techniques in detecting the material defect profile. However, not many researchers have described in detail the structure and issues of GMR sensors and their application in eddy current techniques for nondestructive testing. This paper will describe the implementation of GMR sensors in non-destructive testing eddy current testing. The first part of this paper will describe the structure and principles of GMR sensors. The second part outlines the principles and types of eddy current testing probe that have been studied and developed by previous researchers. The influence of various parameters on the GMR measurement and a factor affecting in eddy current testing will be described in detail in the third part of this paper. Finally, this paper will discuss the limitations of coil probe and compensation techniques that researchers have applied in eddy current testing probes. A comprehensive review of previous studies on the application of GMR sensors in non-destructive eddy current testing also be given at the end of this paper.

Investigation on transverse defect and cavitation depth in ferrous pipe using melt spun FeSiB ribbon as magnetostrictive sensing element

The investigation addresses the scope of rapidly quenched Fe80Si8B12 ribbons as magnetostrictive sensor (MsS) material to generate guided waves in galvanised iron pipe and evaluation of defects with different geometries and dimensions. Enhancement in the effective defect size (EDS) of transverse and pit type defects increased the MsS signal. However, the backwall echo showed opposing trend (transverse: reduced and pit: increased) with increase in dimensions of these defects. Such behaviour of backwall intensities has been correlated to different type of guided wave strain field distributions around these defects and reflection coefficients.

Optimizing the production of steel with reduction by aluminum, in casting and rolling systems

Data on the metallurgical defects in pipe show that they may be due to nonmetallic oxide inclusions. Analysis of the formation of oxide inclusions from smelting to the continuous casting of steel shows that, in order to reduce the incidence of such defects, additional measures must be taken in the smelting and ladle treatment of the steel. Such measures reduce the content of oxide inclusions in the steel by half. The benefits of this approach are confirmed by the reduced rejection rate of the pipe on account of defects associated with the presence of nonmetallic inclusions.

Quantitative Evaluation of Defect Based on Ultrasonic Guided Wave and CHMM

The axial length of pipe defects is not linear with the reflection coefficient, which is difficult to identify the axial length of the defect by the reflection coefficient method. Continuous Hidden Markov Model (CHMM) is proposed to accurately classify the axial length of defects, achieving the objective of preliminary quantitative evaluation. Firstly, wavelet packet decomposition method is used to extract the characteristic information of the guided wave signal, and Kernel Sliced Inverse Regression (KSIR) method is used to reduce the dimension of feature set. Then, a variety of CHMM models are trained for classification. Finally, the trained models are used to identify the artificial corrosion defects on the outer surface of the pipe. The results show that the CHMM model has better robustness and can accurately identify the axial defects.

Longitudinal mode magnetostrictive patch transducer array employing a multi-splitting meander coil for pipe inspection

Recently, a magnetostrictive patch transducer (MPT) by means of the highly magnetostrictive (such as nickel or iron–cobalt alloy) patch attached on the specimen has been applied in nondestructive ultrasonic testing in waveguides. In the study, we proposed a new MPTs array employing a multi-splitting meander coil (MSMC) for generating and receiving longitudinal guided waves in pipes. In the suggested configuration, the directions of the static magnetic field produced by the permanent magnets and the dynamic magnetic field produced by the MSMC are in the axial direction of the pipe. Two finite element models were established to simulate the distribution of the static and dynamic magnetic fields in the patch, respectively. The proposed MSMC was made of flexible printed circuit (FPC), so it could be easily installed on pipe surface. The performance of the proposed MPTs array was experimentally studied. Firstly, it was experimentally verified that the axisymmetric longitudinal guided wave mode, L(0,2), could be effectively generated and received in pipes with the developed MSMC-MPTs array. Secondly, the frequency response characteristics of the developed MSMC-MPTs array were related to D (the distance between adjacent belts of the MSMC). Thirdly, we demonstrated the ability of the developed MSMC-MPTs array for the identification and location of a crack defect in pipes. Finally, we compared the performances of the MSMC-MPTs array and conventional meander coil-MPTs and proved that the signals of the longitudinal guided wave mode could be enhanced by using the developed MSMC-MPTs array.