Research of the Causes of the Defect "Sliver" on the Inner Surface of the Steel Pipe Strength Category Х70

2019 ◽  
Vol 822 ◽  
pp. 16-22
Author(s):  
Pavel Valer'evich Kovalev ◽  
Sergey Vladimirovich Ryaboshuk ◽  
Andrey Igorevich Zhitenev ◽  
Vitaliy Kulikov
Keyword(s):  
Surface Defects ◽  
Steel Pipe ◽  
Strength Category ◽  
Inner Surface

A metallurgical examination of surface defects of pipes made of steel of strength category X70 was carried out. The characteristic microstructural features of defects were determined. The causes of the formation of surface defects of the pipe were established. Comparison of the actual and calculated compositions of the detected satellite inclusions was conducted.

An Experimental and Numerical Methodology to Investigate Crack Growth in a 304L Austenitic Stainless Steel Pipe Under Thermal Fatigue

2010 ◽  
Author(s):  
Pauline Bouin ◽  
Antoine Fissolo ◽  
Ce´dric Gourdin
Keyword(s):  
Finite Element ◽  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Crack Growth ◽  
Thermal Fatigue ◽  
Thermal Loading ◽  
Steel Pipe ◽  
Design Stage ◽  
Inner Surface ◽  
Stainless Steel Pipe

This paper covers work carried out by the French Atomic Energy Commission (CEA) to investigate on mechanisms leading to cracking of piping as a result of thermal loading existing in flow mixing zones. The main purpose of this work is to analyse, with a new experiment and its numerical interpretation, and to understand the mechanism of propagation of cracks in such components. To address this issue, a new specimen has been developed on the basis of the Fat3D experiment. This thermal fatigue test consists in heating a 304L steel pre-cracked tube while cyclically injecting ambient water onto its inner surface. The tube is regularly removed from the furnace for a crack characterisation. Finally, the crack growth is evaluated from the crack length differences between two stops. In parallel, a finite element analysis is developed using the finite element Cast3M code. A pipe with a semi-elliptical crack on its inner surface is modelled. A cyclic thermal loading is imposed on the tube. This loading is in agreement with experimental data. The crack propagates through the thickness. A prediction of the velocity of the crack is finally assessed using a Paris’ law type criteria. Finally, this combined experimental and numerical work on 304L austenitic stainless steel pipes will enable to improve existing methods to accurately predict the crack growth under cyclic thermal loadings in austenitic stainless steel pipe at the design stage.

Influence of Inner Surface Defects on the Fatigue Strength of Pipe Subjected to Cyclic Internal Pressure

1978 ◽  
Vol 100 (4) ◽  
pp. 360-368
Author(s):  
Y. Yazaki ◽  
S. Hashirizaki ◽  
S. Nishida ◽  
C. Urashima
Keyword(s):  
Fatigue Strength ◽  
Internal Pressure ◽  
Test Specimen ◽  
Surface Defects ◽  
Fatigue Crack Initiation ◽  
Internal Surface ◽  
Fatigue Tests ◽  
Inner Surface ◽  
Surface Notch ◽  
Medium Diameter

Cyclic internal oil pressure fatigue tests were carried out on medium-diameter ERW pipes of API 5LX - X60 in an attempt to determine the influence of surface defects on the fatigue strength. Experimental factors investigated were the depth and location of internal surface notch in relation to the axis of pipe. The specimen was subjected to cyclic internal pressure, the cyclic rate being 0.3–0.5 Hz. During the test, Acoustic Emission (AE) techniques were applied to detect the fatigue crack initiation. Along with the aforementioned fatigue tests, pulsating tension fatigue tests were carried out on specimens with the same surface notches as the cyclic internal pressure fatigue test specimen.

Influence of Geometrical Features of Material Defects on the Identification Level by the Eddy Current Method

2015 ◽  
Vol 237 ◽  
pp. 136-141
Author(s):  
Wojciech Jóźwik ◽  
Tomasz Samborski
Keyword(s):  
Eddy Current ◽  
Surface Defects ◽  
Roller Bearing ◽  
Current Method ◽  
Eddy Current Method ◽  
Cross Sectional ◽  
Tapered Roller Bearing ◽  
Geometrical Features ◽  
Inner Surface ◽  
The Face

The article presents the results of the influence of geometrical features of defects in materials on the level of identification by the eddy current method. The study involved the inner ring of the tapered roller bearing. Four test defects, located at a constant distance from the inner surface, and a subsurface marker defect were performed in the treadmill of the tested ring. The test defects had a constant cross-sectional area in a perpendicular direction to the surface of the eddy current head. The geometrical features of each defect were the following: shape, the perimeter of the defect projected onto the surface of the ring, and the width and height of the defect projected on the face of the measuring head. The study involved an inner surface (subsurface defect detection) and external surface (the study of surface defects). It has been shown that the shape of the defect affects the level of detection using the eddy current method.

scholarly journals Fast γ Photon Imaging for Inner Surface Defects Detecting

Sensors ◽  
2021 ◽  
Vol 21 (23) ◽  
pp. 8134
Author(s):  
Min Yao ◽  
Guangdong Luo ◽  
Min Zhao ◽  
Ruipeng Guo ◽  
Jian Liu
Keyword(s):  
Maximum Likelihood ◽  
Surface Defects ◽  
Internal State ◽  
Structural Characteristics ◽  
Expectation Maximization Algorithm ◽  
Emission Computed Tomography ◽  
Detection Accuracy ◽  
Back Projection ◽  
Reconstruction Algorithms ◽  
Inner Surface

Only a few effective methods can detect internal defects and monitor the internal state of complex structural parts. On the basis of the principle of PET (positron emission computed tomography), a new measurement method, using γ photon to detect defects of an inner surface, is proposed. This method has the characteristics of strong penetration, anti-corrosion and anti-interference. With the aim of improving detection accuracy and imaging speed, this study also proposes image reconstruction algorithms, combining the classic FBP (filtered back projection) with MLEM (maximum likelihood expectation Maximization) algorithm. The proposed scheme can reduce the number of iterations required, when imaging, to achieve the same image quality. According to the operational demands of FPGAs (field-programmable gate array), a BPML (back projection maximum likelihood) algorithm is adapted to the structural characteristics of an FPGA, which makes it feasible to test the proposed algorithms therein. Furthermore, edge detection and defect recognition are conducted after reconstructing the inner image. The effectiveness and superiority of the algorithm are verified, and the performance of the FPGA is evaluated by the experiments.

Evaluation of the Effect of Holding the Mandrel in the Extreme Position of the FQM Mill on the Formation of Surface Defects

2021 ◽  
Vol 316 ◽  
pp. 375-379
Author(s):  
Vladimir Toporov ◽  
Alexander Khalezov ◽  
Danis Nukhov
Keyword(s):  
High Performance ◽  
Surface Defects ◽  
Defect Formation ◽  
Stable Process ◽  
Continuous Mill ◽  
Continuous Rolling ◽  
Extreme Position ◽  
Wide Range ◽  
Inner Surface ◽  
Technical Recommendations

Modern continuous mills FQM are high-performance technological units that allow you to get products of a wide range. The paper presents the results of the study of the effect of the time of holding the mandrel in the extreme position of the continuous mill FQM (Fine Quality Mill) on the probability of defect formation of surface defects. The problems of сcomputational simulation of the process of continuous rolling of pipes were set and solved. It is established that the increase in the holding time of the mandrel allows to reduce the sliding of the metal on the surface of the tool, and contributes to a stable process of removing the mandrel without the formation of defects on the inner surface of the draft pipe. The results of solving the problems of сcomputational modeling allowed to formulate technical recommendations aimed at reducing the probability of surface defects in the production of pipes at the FQM mill.

Development of the Microrobot for Indoor Pipeline

2014 ◽  
Vol 658 ◽  
pp. 724-729
Author(s):  
Mihai Olimpiu Tătar ◽  
Dan Mândru ◽  
Vasile Sergiu Jisa
Keyword(s):  
Pipe Wall ◽  
Small Diameter ◽  
Dc Motor ◽  
Steel Pipe ◽  
Inner Surface ◽  
Inner Diameter ◽  
Torsion Springs ◽  
Structure And Design

Generally the in-pipe microrobots can be used for the mobile inspection of small diameter pipes. This paper describes the structure and design of an in-pipe microrobot. The suggested microrobot was built to use wheels for locomotion, and to be able to adapt its structure according to the inner diameter of the inspected pipe. Being powered using wires, the microrobot is not energetically autonomous. The microrobot is able to maintain its balanced state due to the pressure exerted by the wheels onto the inner surface of the pipe and it can adapt to pipe diameters ranged between 30 an 50 mm. The driving is achieved by using a DC motor with integrated gearbox. Motion transmission from the motor to the drive wheels is done by using three geared transmissions and the contact between the wheels and the pipe wall is continuously maintained trough a torsion springs mounted on the rotational joints of the wheel support elements. The testing of the microrobot was performed using a steel pipe with the diameter of 50 mm, placed both horizontally and vertically.

Study on Abrasive Flow Machining Pipe Inner Surface

2011 ◽  
Vol 332-334 ◽  
pp. 2014-2017
Author(s):  
Li Sheng Wu ◽  
Ji Yuan Zhang
Keyword(s):  
Surface Roughness ◽  
Surface Defects ◽  
Small Diameter ◽  
Abrasive Flow Machining ◽  
Inner Surface

For it is difficult to machining inner surface of small diameter pipes, abrasive flow machine (AFM) had been tested to polish the inner surface. Pipe inner surface AFM experiment and AFM defects remove experiment were carried out on MB9211 AFM machine, and conclusions were obtained that AMF is a very effective process to polish pipe inner surface, roughness significantly reduce after processing and can remove certain surface defects.

The Measurement and Modelling of Residual Stresses in a Stainless Steel Pipe Girth Weld

2008 ◽  
Author(s):  
K. Ogawa ◽  
L. O. Chidwick ◽  
E. J. Kingston ◽  
R. Dennis ◽  
D. Bray ◽  
...  
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Residual Stresses ◽  
Outer Surface ◽  
Mixed Mode ◽  
Steel Pipe ◽  
Outer Diameter ◽  
Hardening Model ◽  
Inner Surface ◽  
Stainless Steel Pipe

This paper presents results from a program of residual stress measurements and modelling carried out for a pipe girth weld of 369 mm outer diameter and 40 mm thickness. The component consisted of two 316 stainless steel pipe sections joined together using a “single-V” nickel base alloy (alloy 82) weld. The residual stresses were measured using the Deep-Hole Drilling (DHD) technique and modelled using ABAQUS. Biaxial, through-thickness residual stresses were measured through the weld centreline at a total of 6 different locations around the component. At three of the measurement locations the DHD process was carried out from the outer surface of the component with the remaining three, one of which coinciding with the weld start/stop position, carried out from the inner surface of the component. The differences in DHD process application (i.e. outer-to-inner or inner-to-outer) was carried out as a sub-objective to investigate the sequence of residual stress relaxation and its influence on the measured results. Good measurement repeatability was found between all locations. The hoop residual stresses were tensile at the outer surface, increasing to a maximum of 350 MPa at 10 mm depth, then decreasing to a minimum of −325 MPa at a depth of 34 mm, before increasing again towards the inner surface. The axial residual stresses were found to be similar in profile to the hoop residual stresses albeit lower in absolute magnitude by roughly 100 MPa. For this component it was found that the hoop residual stresses showed an influence of process direction, whereas for the axial residual stresses no influence was found. The modelling of the residual stresses generated was undertaken using a 2D axisymmetric finite element analysis containing 25 discrete weld beads. Each of the 25 weld beads were analysed sequentially using the following stages: heat source modelling, thermal analysis, elastic-plastic mechanical analysis. The sensitivity of the residual stresses generated with respect to the material hardening model used was investigated (i.e. kinematic, isotropic and mixed mode – kinematic/isotropic). Generally, the isotropic hardening model produces the highest predictions, the kinematic hardening model produces the lowest predictions with the mixed mode model lying in-between. Good agreement was found between the measured and modelled residual stresses. The main discrepancy existed in the hoop direction with the modelled residual stresses being the most tensile by roughly 200 MPa at depths within 15 mm of the outer surface of the pipe.

Influence of Case Hardening on Fatigue Resistance of Models of Hollow Shafts with Production Surface Defects

2011 ◽  
Vol 465 ◽  
pp. 243-246
Author(s):  
M. Čipera ◽  
Ivo Černý ◽  
V. Pospíchal ◽  
Dagmar Mikulová ◽  
Ivan Fürbacher
Keyword(s):  
Fatigue Resistance ◽  
Surface Defects ◽  
Hardened Layer ◽  
Point Of View ◽  
Case Hardening ◽  
Bending Tests ◽  
Variable Diameter ◽  
Inner Surface ◽  
Hollow Shafts ◽  
Compressive Residual Stresses

This work analyses an influence of case hardening on fatigue resistance of models of hollow shafts which have a variable diameter ranging from 40 mm to 67 mm, wall thickness of 7 mm and production surface defects on an inner surface layer of the hollow shafts. Case hardened (on both sides) and non case hardened shafts were tested. Both types of shafts were made out of 16MnCrS5 (DIN) steel by cold reduction rolling and were subjected to a flat bending. Tests indicated that the fatigue resistance of the case hardened shafts was significantly higher. The main reason for the lower resistance of the non case hardened shafts was initiation of magistral cracks from the defects on inner surfaces. In case of the case hardened shafts the magistral cracks initiated from the notch on outer surfaces where macroscopic stress was maximal. Different mechanisms of the cracking are discussed from the point of view of compressive residual stresses in the case hardened layer.

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