Residual Stress in Girth Welds: Seeing Measurement Data Differently

2019 ◽  
Author(s):  
Ali Mirzaee-Sisan ◽  
Guiyi Wu
Keyword(s):  
Residual Stress ◽  
Statistical Analysis ◽  
Statistical Approach ◽  
Stress Measurement ◽  
Measurement Data ◽  
Outer Zone ◽  
Middle Zone ◽  
Data Points ◽  
Girth Welds

Abstract This paper studies some of the recent residual stress measurement data on pipeline girth welds, which are available in the open literature, using a statistical approach. The measurement data points from residual stresses profiles are separated into three different zones, ie, outer zone, inner zone and middle zone, to study their distributions statistically. This statistical analysis indicates that for the region close to the outer surface, where welding is most likely to produce critical flaws, most of the reported measurement data points lie below the yield strength of the base metal. The paper concludes by presenting a case study using deterministic and probabilistic fracture analyses and providing some recommendations for further improvement of the relevant codes and standards.

Residual Stress Profiles of Pipe Girth Weld Using a Stress Decomposition Method

2014 ◽  
Author(s):  
Huaguo Teng ◽  
Steve Bate
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Stress Measurement ◽  
Heuristic Method ◽  
Measurement Data ◽  
Stress Profile ◽  
Residual Stress Profile ◽  
Stress Components ◽  
Stress Profiles ◽  
Girth Welds

The application of procedures such as R6 or BS7910 for the structural assessment of defects in pressurised components containing residual stresses requires knowledge of the through-wall residual stress profile. Currently there is much interest in improving the residual stress profiles that are provided in the procedures. In this paper we present an improved analysis of residual stresses of the pipe girth welds by applying the developed heuristic method to one set of extended residual stress measurement data. The through-thickness residual stress is decomposed into three stress components: membrane, bending and self-equilibrating. The heuristic method was applied to the three components separately, so that the residual stress profile was a combination of the three stress components. This form provides not only a clear physical basis for the residual stress profile, but is also convenient for defect assessment where only the membrane and bending stress components are important.

scholarly journals Statistical analysis of the reproducibility of residual stress measurements in cold extruded parts

2021 ◽  
Author(s):  
Fabian Jaeger ◽  
Alessandro Franceschi ◽  
Holger Hoche ◽  
Peter Groche ◽  
Matthias Oechsner
Keyword(s):  
Residual Stress ◽  
Statistical Analysis ◽  
Stress Measurement ◽  
Industrial Applications ◽  
Cold Extrusion ◽  
X Ray Diffraction ◽  
Forming Process ◽  
X Ray ◽  
Stress States ◽  
Key Aspects

AbstractCold extruded components are characterized by residual stresses, which originate from the experienced manufacturing process. For industrial applications, reproducibility and homogeneity of the final components are key aspects for an optimized quality control. Although striving to obtain identical deformation and surface conditions, fluctuation in the manufacturing parameters and contact shear conditions during the forming process may lead to variations of the spatial residual stress distribution in the final product. This could lead to a dependency of the residual stress measurement results on the relative axial and circumferential position on the sample. An attempt to examine this problem is made by the employment of design of experiments (DoE) methods. A statistical analysis of the residual stress results generated through X-Ray diffraction is performed. Additionally, the ability of cold extrusion processes to generate uniform stress states is analyzed on specimens of austenitic stainless steel 1.4404 and possible correlations with the pre-deformed condition are statistically examined. Moreover, the influence of the coating, consisting of oxalate and a MoS2 based lubricant, on the X-Ray diffraction measurements of the surface is investigated.

scholarly journals Relasi Antara Investor Pariwisata Dengan Masyarakat Lokal Di Desa Pakraman Laplapan Desa Petulu Kecamatan Ubud

2018 ◽  
Vol 5 (1) ◽  
pp. 51
Author(s):  
I Ketut Agus Gita Suprapta ◽  
I Gusti Agung Oka Mahagangga
Keyword(s):  
Social Conflict ◽  
Outer Zone ◽  
Limited Resources ◽  
Middle Zone ◽  
Literature Study ◽  
Tourist Destination ◽  
Economic Resource ◽  
Good Relationship ◽  
The Relationship

The research titled is "relationship between tourism investors and lokal communities in Desa Pakraman Laplapan Petulu Village (Case Study Social Conflict)", purpose to understand the relationship undertaken by tourism investors with lokal communities that happened in the Ubud tourist destination. Data were collected through observation, interview and literature study. Infoman taken by purposive, which determine the informan with a certain considerations that are considered able to provide data to the maximum in accordance with the criteria of the research objectives. The collected data were analyzed descriptively qualitative. An important concept in the study include the concept of Typology Relations Styling in 3 Zone which consists of the outer zone, the middle zone and center zone. The results of this study indicate that, Desa Pakraman Laplapan as a region lies in the outer zone. Relationships that lived between tourism investors and lokal communities in Desa Pakraman Laplapan patterned conflictual. This pattern is shown by the regulation provided by the lokal community to tourism investors who are less rational. As for the view of the conflict is a way to snatch for limited resources. And one of them is the economic resource owned by the investor. Styling tourism investor relations with the lokal community in Desa Pakraman Laplapan has been sticking to the surface of the endless conflict. In this case, the farmer must make good relationship with tourism investors because it would help to farmers.   Keywords: Relationship, Investors, Lokal Communities, Conflict

The Mechanics Basis of Residual Stress Profiles in Proposed API 579 Appendix E

2006 ◽  
Author(s):  
P. Dong ◽  
Z. Cao
Keyword(s):  
Residual Stress ◽  
Heat Input ◽  
Stress Measurement ◽  
Measurement Data ◽  
Stress Profile ◽  
Continuous Change ◽  
Parametric Function ◽  
Residual Stress Profile ◽  
Stress Profiles ◽  
Pipe Geometry

In this paper, the mechanics basis underlying the parametric through-thickness residual stress profiles proposed for the revised API 579 Appendix E are presented. The proposed residual stress profiles are governed to a large extent by a unified parametric function form valid for a broad spectrum of pipe and vessel welds. The functional relationship is established based on the comprehensive knowledge base developed within a recent major international joint industry project (JIP) under the auspice of Pressure Vessel Research Council (PVRC) and a large amount of residuals stress measurement data from recent literature. One of the most important features associated with the proposed revision is that residual stress profile is uniquely determined by two important sets of governing parameters: (1) parameters relevant to pipe geometry, i.e., r/t and t; (2) a parameter related to welding linear heat input Q (J/mm), referred to as the characteristic heat input Qˆ which has a dimension of J/mm3. As a result, the corresponding through-wall residual stress distribution exhibits a continuous change as a function of r/t, t, and Qˆ, instead of falling into a few discrete and unrelated profiles, as seen in the current Codes and Standards.

Errors in Residual Stress Measurements due to Random Counting Statistics

1970 ◽  
Vol 14 ◽  
pp. 377-388 ◽  
Author(s):  
C. J. Kelly ◽  
M. A. Short
Keyword(s):  
Residual Stress ◽  
Standard Deviation ◽  
Stress Measurement ◽  
Mathematical Expression ◽  
X Ray Diffraction ◽  
Intensity Maximum ◽  
X Ray ◽  
Diffraction Angle ◽  
Data Points ◽  
Counting Statistics

AbstractThe measurement of residual stress, using X-ray diffraction techniques, is based on the change in diffraction angle determined for the Intensity maximum of some suitable reflection from the sample when this is placed consecutively with its surface at two different angles to the diffracting planes. These diffraction angles may be obtained in a variety of ways, but are most often calculated from measurements of three X-ray diffraction intensities at angles selected in the immediate vicinity of the peak maximum at each sample angle and fitting each set of data to a parabolic curve. A simple mathematical expression may be derived relating the diffraction angles, and hence the residual stress, to the measured X-ray intensities; there will, however, be statistical errors in the calculated diffraction angles due to random counting errors in the measurement of the X-ray diffraction intensities. From the expression relating the residual stress to the X-ray intensities an equation has been derived giving the standard deviation in the residual stress due to random counting errors. In addition, a simple approximation has been obtained from this equation showing that the standard deviation is decreased by increasing the number of counts accumulated for each X-ray intensity measurement and by increasing the size of the angular increments between the data points. It will also be shown that, using the approximation, it is possible to estimate in advance the number of accumulated counts at each point necessary to attain a desired standard deviation in a residual stress measurement.

Problems in the Averaging of Neutron Diffraction Stress Data from Round-Robin Campaigns

2008 ◽  
Vol 571-572 ◽  
pp. 283-288 ◽  
Author(s):  
Robert C. Wimpory ◽  
Carsten Ohms ◽  
Michael Hofmann ◽  
Rainer Schneider ◽  
A.G. Youtsos
Keyword(s):  
Residual Stress ◽  
Neutron Diffraction ◽  
Measurement Techniques ◽  
Measurement Data ◽  
Systematic Errors ◽  
Round Robin ◽  
Error Bar ◽  
Data Points ◽  
Outlier Data ◽  
Few Data

In recent years the use of a special Bayesian approach on averaging ‘round-robin’ residual stress data has been implemented. This averaging approach is useful in that it copes with the situation where systematic errors have occurred in one or more of the measurements and thus diminishes the influence of these particular ‘wrong value’ outlier data points. The analyses not only take into account the measurand value, but also the uncertainties associated with each measurand. It should deal with data that may contain individual members with uncertainties larger than the stated error and assumes that the quoted error bar is only a lower bound on the uncertainty. This work shows what could happen when there is a ‘strong mismatch’ in uncertainties when averaging over a limited amount of data. It has been observed that in a case where there are few data points (for example 5 or less), a strong bias can occur towards data points with a relatively small quoted uncertainty compared to other data points with larger quoted uncertainties. A ‘mismatch’ in uncertainty quotation can arise when averaging very good data with poorer data or when averaging with data obtained from other measurement techniques. This effect is demonstrated in this work by using fictitious data and also based on the example of real measurement data obtained by neutron diffraction.

Determination of Residual Stress Profiles of Pipe Girth Weld Using a Unified Parametric Function Form

2009 ◽  
Author(s):  
Huaguo Teng ◽  
Steve K. Bate ◽  
David W. Beardsmore
Keyword(s):  
Residual Stress ◽  
Stress Measurement ◽  
Heuristic Method ◽  
Measurement Data ◽  
Stress Profile ◽  
Function Form ◽  
Parametric Function ◽  
Residual Stress Profile ◽  
Stress Profiles ◽  
Pipe Geometry

In this paper we present an improved analysis of residual stress data of a pipe girth weld by applying the developed heuristic method to one set of high-quality residual stress measurement data. The through-thickness residual stress is expressed as a parametric function form which is a combination of three stress components: membrane, bending and self-equilibrating. This parametric function form provides not only a clear physical basis for the residual stress profile, but is also closely related to two important governing parameters, i.e. the pipe geometry and the welding heat input. The residual stress profiles obtained are also compared with results predicted by the Bayesian method as well as the profiles from the UK R6 procedure and the US API 579 code.

Statistical Analysis of X-ray Residual Stress Measurement Using the Half-Width Method

1982 ◽  
Vol 10 (2) ◽  
pp. 38 ◽  
Author(s):  
R Horstman ◽  
KA Peters ◽  
BM Schindler ◽  
RL Meltzer ◽  
M Bruce Vieth ◽  
...  
Keyword(s):  
Residual Stress ◽  
Statistical Analysis ◽  
Stress Measurement ◽  
Half Width ◽  
Residual Stress Measurement ◽  
X Ray

Statistical Analysis of Residual Stress Profiles Using a Heuristic Method

2008 ◽  
Author(s):  
H. Teng ◽  
S. K. Bate ◽  
D. W. Beardsmore
Keyword(s):  
Residual Stress ◽  
Statistical Analysis ◽  
Least Squares ◽  
Least Squares Method ◽  
Expert Knowledge ◽  
Heuristic Method ◽  
Measurement Data ◽  
Expert Judgement ◽  
Stress Profile ◽  
Residual Stress Profile

In this paper we present a recently developed heuristic method for statistical analysis of residual stress that is based on a combination of the weighted least-squares method and the application of expert judgement. The least-squares method allows a model of the best residual stress profile to be determined as a linear combination of basis functions; the expert knowledge gives the flexibility of applying expert judgement to determine the weights from the observed scatter in the residual stress data. The heuristic method has been applied to a set of measurement data of a Welded Bead-on-Plate specimen. The results show that with the heuristic method, it is possible to obtain less conservative residual stress profile to a known confidence level.

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