Stress Redistribution During Local Annealing of a Multi-Pass Butt-Welded Pipe

1986 ◽  
Vol 108 (2) ◽  
pp. 125-130
Author(s):  
B. L. Josefson
Keyword(s):  
Pipe Wall ◽  
Rotational Symmetry ◽  
Stress Fields ◽  
Pipe Material ◽  
Pipe Surface ◽  
Pipe Wall Thickness ◽  
Final Stress ◽  
Welded Pipe ◽  
Hoop Stresses ◽  
Mn Steel

Stress redistributions during local Post Weld Heat Treatments (PWHT) are numerically studied for a multi-pass butt-welded pipe with mechanically unrestrained ends. The pipe material is a micro-alloyed C-Mn steel. Temperature and stress fields developed during welding and PWHT are determined from a FE-analysis where rotational symmetry is assumed. Use of heaters with a total axial width less than four times the pipe wall thickness is found to result in substantially different final stress fields than those obtained after a uniform (furnace) heat treatment. The tensile axial and hoop stresses on the inner pipe surface near the centre section of the weldment are considerably higher after a local PWHT. The differences were found to arise mainly during the cooling periods of the PWHTs.

Experimental Characterization of Flow Induced Vibration in Fully Developed Turbulent Pipe Flow

2009 ◽  
Author(s):  
Andrew S. Thompson ◽  
Daniel Maynes ◽  
Thomas Shurtz ◽  
Jonathan D. Blotter
Keyword(s):  
Wall Thickness ◽  
Pipe Wall ◽  
Wall Pressure ◽  
Surface Velocity ◽  
Pipe Diameter ◽  
Pipe Material ◽  
Pipe Surface ◽  
Pipe Wall Thickness ◽  
Wall Pressure Fluctuations ◽  
Pipe Vibration

In this paper we present results of an experimental investigation that characterizes the wall vibration of a pipe with a fully-developed turbulent flow passing through it. Experiments were conducted in a water flow loop where the influences of average fluid speed, pipe diameter, pipe wall thickness, and pipe material on the overall pipe vibration were investigated. The pipe vibration was characterized by accelerometer instruments mounted on the surface of the pipe at multiple locations and the rms of the pipe wall acceleration, velocity, and displacement were measured. Simultaneous measurements of the local temporal fluctuations in the wall pressure were also obtained. Specifically, experiments were conducted in test sections of internal diameters of 3.81 cm – 10.16 cm, pipe wall thickness to diameter ratio ranging from 0.06 – 0.10, and with PVC, aluminum, and stainless steel pipe materials. The experiments were conducted with average fluid speeds ranging from 0 – 11.5 m/s with an accompanying range in the dynamic pressure from 0 – 1 atm. The results show that the rms of the acceleration is proportional to the average fluid speed raised to the 2.12 power. Also, the rms of the pipe surface velocity and the pipe displacement scale with the average fluid speed to the 1.62 and 1.16 powers respectively. Further, the rms of the pipe acceleration and pipe speed increase with increasing pipe diameter, while the pipe modulus of elasticity appears to exert negligible influence on the magnitude of the measured vibrations. The rms of the wall pressure fluctuations scale with the fluid speed raised to the 2.0 power.

Using MFL Corrosion Signals to Determine Biaxial Stress in Operating Pipelines

2000 ◽  
Author(s):  
Alfred E. Crouch
Keyword(s):  
Magnetic Flux ◽  
Internal Pressure ◽  
Pipe Wall ◽  
Axial Stress ◽  
Wall Stress ◽  
Biaxial Stress ◽  
Metal Loss ◽  
Pipe Surface ◽  
The Difference ◽  
Hoop Stresses

Previous work has shown that a corrosion assessment more accurate than B31.G or RSTRENG can be made if pipeline stresses are considered. A shell analysis can be carried out if both the corrosion profile and local pipe wall stresses are known. The corrosion profile can be approximated from analysis of magnetic flux leakage (MFL) signals acquired by an inline inspection tool (smart pig), but a measure of pipe wall stress has not been available. Approximations have been made based on pipe curvature, but a more direct measurement is desirable. Recent work has produced data that show a correlation between multi-level MFL signals from metal-loss defects and the stress in the pipe wall at the defect location. This paper presents the results of MFL scans of simulated corrosion defects in pipe specimens subjected to simultaneous internal pressure and four-point bending. MFL data were acquired at two different magnetic excitations using an internal scanner. The scanner’s sensor array measured axial, radial and circumferential magnetic flux components on the inner pipe surface adjacent to the defect. Comparison of the signals at high and low magnetization yields an estimate of the difference between axial and hoop stresses. If internal pressure is known, the hoop component can be determined, leaving data proportional to axial stress.

Effect of Including the Bauschinger Phenomenon in the Formula for Collapse Pressure of Thin-Walled Pipes

2020 ◽  
Author(s):  
Alastair Walker ◽  
Ruud Selker ◽  
Ping Liu ◽  
Erich Jurdik
Keyword(s):  
Hydrostatic Pressure ◽  
Wall Thickness ◽  
Bauschinger Effect ◽  
Pipe Wall ◽  
Large Diameter ◽  
Pipe Material ◽  
Pipe Wall Thickness ◽  
Collapse Pressure ◽  
Compressive Stresses ◽  
Thin Walled

Abstract The method presented by DNVGL in DNVGL-ST-F101 [1], “Submarine pipeline systems”, 2017, for calculating the collapse pressure of submerged pipelines is well-known for design of pipes intended to operate in very deep water. Such pipes are regarded as quite thick-walled with diameter to wall thickness ratio in the range of 15 to 30. There is now substantial experience in the practical manufacture, installation and operation of such pipes. Recently there has been a growing use of large diameter pipelines to transport high volumes of gas over great lengths at moderate water depths. The pipes are considered to be thin-walled with ratios of diameter to wall thickness in the range of 30 to 45. This paper assesses the validity of the DNVGL design method when applied to the design of such thin-walled pipes. A particular aspect of the buckling pressure of large diameter pipes is the effect of the Bauschinger phenomenon. The phenomenon occurs when pipes made using the UOE method are subjected to internal pressure, to provide expansion of the pipe during manufacture, thus reducing the out-of-roundness of the pipe wall, and subsequently subjected to external hydrostatic pressure during pipeline operation. To date the Bauschinger phenomenon has been recognised as resulting in a reduction of the circumferential compressive yield of the pipe material. This reduction is accommodated in the DNVGL design formula. Recent research into material properties has shown that the Bauschinger effect also has the effect of reducing the modulus of steel materials over a range of values of applied circumferential compressive stresses. The paper reviews the basis of the Bauschinger phenomenon and presents results from very detailed accurate testing of UOE pipe material. The tests determine the levels of modulus for pipes subject to circumferential compressive stresses. Although results for compressive stress-strain values have previously been available for pipes subject to high levels of hydrostatic pressure it has been considered that the Bauschinger effect is not generally significant for thick-walled pipes. The tests reported here consider the calculation of material modulus levels for low levels of stress that correspond to the buckling stress of thin-walled pipes. The calculated collapse pressure for such pipes is examined in this paper and compared to corresponding results from the DNVGL design formula to provide guidance on the effect of design levels of pipe wall thickness due to inclusion of the Bauschinger effect. The comparisons are for example pipe wall thickness and material conditions. Conclusions are drawn that including the Bauschinger effect in the calculated pipe wall thickness can have a beneficial effect with regard to pipe manufacturing and installation costs for pipe subjected to mild heat treatment.

Uncertainty Quantification of Wall Thickness of Onshore Gas Transmission Pipelines

2020 ◽  
Author(s):  
Wenxing W. Zhou ◽  
Ji Bao
Keyword(s):  
Wall Thickness ◽  
Pipe Wall ◽  
Metal Loss ◽  
Pipeline System ◽  
Pipe Wall Thickness ◽  
Reliability Based Design ◽  
Wide Range ◽  
Pipe Joints ◽  
Welded Pipe ◽  
Transmission Pipelines

The present study quantifies probabilistic characteristics of the wall thickness of welded pipe joints in onshore gas transmission pipelines based on about 5900 field-measured wall thicknesses collected from a pipeline system in Canada. The collected data cover a wide range of the pipe nominal wall thickness, from 3.18 to 16.67 mm. By considering the measurement error involved in the collected wall thickness data, statistical analyses indicate that the actual-over-nominal wall thickness ratio (AONR) follows a normal distribution with a mean of 1.01 and a coefficient of variation (COV) ranging from 1.6 to 2.2% depending on the nominal pipe wall thickness. The implications of the developed AONR statistics for the reliability analysis of corroded pipe joints are investigated. This study provides key input to the reliability-based design and assessment of pipelines with respect to various threats such as metal-loss corrosion and stress corrosion cracking.

Stress Redistribution During Annealing of a Multi-Pass Butt-Welded Pipe

1983 ◽  
Vol 105 (2) ◽  
pp. 165-170 ◽  
Author(s):  
B. L. Josefson
Keyword(s):  
Stress Field ◽  
Stress Reduction ◽  
Rotational Symmetry ◽  
Welding Residual Stress ◽  
Residual Stress Field ◽  
Fe Method ◽  
Transient Stress ◽  
Holding Period ◽  
Welded Pipe ◽  
Mn Steel

The reduction of welding stresses during some standard post-weld heat treatments (PWHT) is numerically determined for a multi-pass butt-welded pipe made of a micro-alloyed C-Mn steel. Most of the stress reduction is found to occur during heating to the holding temperature. The further reduction obtained during the subsequent holding period is significant only for holding temperatures above 550°C. Both welding stresses and stresses during annealing were calculated by use of the FE-method assuming rotational symmetry. Experiments performed on a welded pipe indicate that the assumption of rotational symmetry is justified for the welding residual stress field, but not for the transient stress field present during welding of each pass.

The Eddy Current Method of Alloy Drill Pipes Wall Thickness Evaluation: Impact Analysis

2019 ◽  
Vol 970 ◽  
pp. 336-342
Author(s):  
Aleksandr E. Goldshtein ◽  
Vasily Y. Belyankov
Keyword(s):  
Wall Thickness ◽  
Eddy Current ◽  
Impact Analysis ◽  
Pipe Wall ◽  
Current Method ◽  
Eddy Current Method ◽  
Pipe Surface ◽  
Thickness Change ◽  
Pipe Wall Thickness ◽  
Aluminum Pipe

The dependences of the surface eddy current probe added voltage at the interaction of the probe magnetic field with an aluminum pipe from the following main interference factors are determined: the pipe wall thickness, the gap between the probe and the surface of the pipe, the electrical conductivity of the material, the curvature of the pipe wall, the presence of areas with a smooth thickness change of the wedge character and a local spherical thinning, axis misalignment with respect to the pipe surface, the lateral misalignment of the probe axis. The problem is solved with the help of the finite element method (FEM). These data are consistent with the experimental results.

Development of a mathematical model of the influence of wall thickness on the strain rate when profiling pipes by drawing

2020 ◽  
pp. 49-52
Author(s):  
R.A. Okulov ◽  
N.V. Semenova
Keyword(s):  
Mathematical Model ◽  
Strain Rate ◽  
Wall Thickness ◽  
Pipe Wall ◽  
Strain Intensity ◽  
Thickness Strain ◽  
Pipe Wall Thickness

The change in the intensity of the deformation of the pipe wall during profiling by drawing was studied. The dependence of the strain intensity on the wall thickness of the workpiece is obtained to predict the processing results in the production of shaped pipes with desired properties. Keywords drawing, profile pipe, wall thickness, strain rate. [email protected]

Modified Equation to Predict Leak/Rupture Criteria for Axially Through-Wall Notched X80 and X100 Linepipes Having Higher Charpy Energy

2004 ◽  
Author(s):  
Shinobu Kawaguchi ◽  
Naoto Hagiwara ◽  
Mitsuru Ohata ◽  
Masao Toyoda
Keyword(s):  
Fracture Toughness ◽  
Flow Stress ◽  
Pipe Material ◽  
Test Results ◽  
Absorbed Energy ◽  
Bending Tests ◽  
Full Scale Tests ◽  
Hoop Stresses ◽  
The Relationship ◽  
Modified Equation

A method of predicting the leak/rupture criteria for API 5L X80 and X100 linepipes was evaluated, based on the results of hydrostatic full-scale tests for X60, X65, X80 and X100 linepipes with an axially through-wall (TW) notch. The TW notch test results clarified the leak/rupture criteria, that is, the relationship between the initial notch lengths and the maximum hoop stresses during the TW notch tests. The obtained leak/rupture criteria were then compared to the prediction of the Charpy V-notch (CVN) absorbed energy-based equation, which has been proposed by Kiefner et al. The comparison revealed that the CVN-based equation was not applicable to the pipes having a CVN energy (Cv) greater than 130 J and flow stress greater than X65. In order to predict the leak/rupture criteria for these linepipes, the static absorbed energy for ductile cracking, (Cvs)i, was introduced as representing the fracture toughness of a pipe material. The (Cvs)i value was determined from the microscopic observation of the cut and buffed Charpy V-notch specimens after static 3-point bending tests. The CVN energy in the original CVN-based equation was replaced by an equivalent CVN energy, (Cv)eq’ which was defined as follows: (Cv)eq = 4.5 (Cvs)i. The leak/rupture criteria for the X80 and X100 linepipes with higher CVN energies were reasonably predicted by the modified equation using the (Cvs)i value.

Leak Testing

2021 ◽  
pp. 143-147
Author(s):  
Charles Becht
Keyword(s):  
Wall Thickness ◽  
Pipe Wall ◽  
Piping System ◽  
Pipe Wall Thickness ◽  
Pressure Testing ◽  
Leak Testing ◽  
Piping Systems ◽  
Design Pressure ◽  
Important Test

While the exercise of pressurizing a piping system and checking for leaks is sometimes called pressure testing, the Code refers to it as leak testing. The main purpose of the test is to demonstrate that the piping can confine fluid without leaking. When the piping is leak tested at pressures above the design pressure, the test also demonstrates that the piping is strong enough to withstand the pressure. For large bore piping where the pipe wall thickness is close to the minimum required by the Code, being strong enough to withstand the pressure is an important test. For small bore piping that typically has a significant amount of extra pipe wall thickness, being strong enough is not in question. Making sure that the piping is leak free is important for all piping systems.

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