On the Mechanics of Residual Stresses in Girth Welds

2006 ◽  
Vol 129 (3) ◽  
pp. 345-354 ◽  
Author(s):  
P. Dong
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Relative Importance ◽  
Stress Distributions ◽  
Unified Framework ◽  
Joint Geometry ◽  
Weld Residual Stress ◽  
Girth Welds ◽  
Welding Procedure

In this paper, some of the important controlling parameters governing weld residual stress distributions are presented for girth welds in pipe and vessel components, based on a large number of residual stress solutions available to date. The focus is placed upon the understanding of some of the overall characteristics in through-wall residual stress distributions and their generalization for vessel and pipe girth welds. In doing so, a unified framework for prescribing residual stress distributions is outlined for fitness-for-service assessment of vessel and pipe girth welds. The effects of various joint geometry and welding procedure parameters on through thickness residual stress distributions are also demonstrated in the order of their relative importance.

On the Mechanics of Residual Stresses in Girth Welds

2004 ◽  
Author(s):  
P. Dong
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Relative Importance ◽  
Stress Distributions ◽  
Unified Framework ◽  
Joint Geometry ◽  
Weld Residual Stress ◽  
Girth Welds ◽  
Welding Procedure

In this paper, some of the important controlling parameters in governing weld residual stress distributions are presented for girth welds in pipe and vessel components, based on a large number of residual stress solutions available to date. The focus is placed upon the understanding of some of the overall characteristics in through-wall residual stress distributions and their generalization for vessel and pipe girth welds. In doing so, a unified framework for prescribing residual stress distributions is then outlined for fitness-for-service assessment of vessel and pipe girth welds. The effects of various joint geometry and welding procedure parameters on through thickness residual stress distributions are also demonstrated in the order of their relative importance.

Effect of Reeling Installation on Weld Residual Stress in Pipeline Girth Welds

2013 ◽  
Author(s):  
T. Sriskandarajah ◽  
Graeme Roberts ◽  
Daowu Zhou
Keyword(s):  
Residual Stress ◽  
Plastic Deformation ◽  
Residual Stresses ◽  
Axial Strain ◽  
Saddle Points ◽  
Parent Material ◽  
Welding Residual Stress ◽  
Residual Stress Field ◽  
Weld Residual Stress ◽  
Girth Welds

A characteristic of pipeline installation by the reeling technique is the generation of high plastic strain around the majority of the pipeline’s circumference as it is spooled onto a drum, under displacement controlled conditions. It is well-known that the application of sufficiently high amounts of mechanical or thermal energy will “anneal” (relax) weld residual stresses and, therefore, under the gross plasticity experienced during reeling it should be expected that initial girth weld residual stresses will be entirely relaxed during the first reel cycle. The residual stress state needs to be taken into account in Engineering Critical Assessment (ECA) procedures of girth welds when predicting allowable defect dimensions. ECA codes such as DNV-OS-F101 and BS7910 assume the welding residual stress to be equal to the yield strength of the parent material and relaxation of welding residual stress under overload is allowed. However, the treatment specified in DNV is established from load-controlled scenarios and may result in un-realistic allowable defect dimensions in displacement-controlled situations such as reeling. Welding residual stress in reeling ECA is concerning to the subsea pipeline industry. By performing reeling simulations with 3D finite element analyses (FEA), this paper examines the welding residual stress before and after reeling and assesses the extent of residual stress relaxation. It was found that reeling axial strain causes significant relaxation of the weld residual stress at the pipe intrados and extrados. At the saddle points there is a slight disruption to the residual stress field. The full weld residual stress is relaxed from a value equal to the material yield stress, and is replaced by a plastic deformation induced stress of much lower magnitude, typically in the order of 100 MPa or less. The plastic deformation stress is of equal magnitude whether or not the pipe section contains initial weld residual stress and, therefore, it is concluded that weld residual stress can be ignored following the first reel cycle.

Measurement of Welding Residual Stress in Reactor Components

2011 ◽  
Author(s):  
Adrian T. DeWald ◽  
Michael R. Hill
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Stress Measurement ◽  
The United States ◽  
Welding Residual Stress ◽  
Contour Method ◽  
Two Dimensional ◽  
Stress Distributions ◽  
Weld Residual Stress ◽  
Metal Weld

Welding residual stresses can significantly impact the performance of structural components. Tensile residual stresses are of particular concern due to their ability to cause significant degradation to the PWSCC resistance of structural materials. The contour method is a residual stress measurement technique capable of generating two dimensional maps of residual stress, which is particularly useful when applied to welds due to the complex residual stress distributions that generally result. The two-dimensional capability of the contour method enables detailed visualization of complex weld residual stress fields. This data can be used to identify locations and magnitude of tensile residual stress hot-spots. This paper provides a summary of the contour method and presents detailed results of contour method measurements made on the dissimilar metal weld region of pressurizer relief nozzles removed from the cancelled WNP-3 plant in the United States as part of the NRC/EPRI weld residual stress (WRS) program [1].

Consistent Treatment of Weld Residual Stresses in Fracture Assessment

2002 ◽  
Author(s):  
P. Dong ◽  
J. K. Hong
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Crack Size ◽  
Stress Distributions ◽  
Stress Effects ◽  
Large Size ◽  
Fracture Assessment ◽  
Girth Welds ◽  
Consistent Treatment

Over the last decade, as more in-depth understanding of weld residual stresses is being achieved, particularly of their characteristic distributions in pressure vessel and piping components, the residual stress effects on stress intensities at welds are becoming better understood. In this paper, some of the important residual stress characteristics are first identified in the form of either “bending” dominated or “self-equilibrating” dominated types for girth welds. The applicability in other joint configurations in welded structures is then discussed, with a collection of validated residual stress distributions. The characterization of both “bending” and “self-equilibrating” types in residual stress distributions provides a consistent framework for stress intensity factor considerations in either fracture and fatigue assessment. The contribution of weld residual stresses to stress intensities at welds are shown to be in the form of K solutions under displacement controlled conditions. The “bending” type residual stresses provide a longer range of influence than “self-equilibrating” type in K solutions. The contribution of “self-equilibrating” type residual stresses to stress intensities is shown to be dominant when crack size is small, while the contribution of the “bending” type dominant for crack size up to a much large size with respect to wall thickness.

Measurement of Welding Residual Stress in Dissimilar Metal Welds Using the Contour Method

2011 ◽  
Author(s):  
Adrian T. DeWald ◽  
Michael R. Hill ◽  
Eric Willis
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Stress Measurement ◽  
The United States ◽  
Welding Residual Stress ◽  
Contour Method ◽  
Two Dimensional ◽  
Stress Distributions ◽  
Dissimilar Metal ◽  
Weld Residual Stress

Welding residual stresses can significantly impact the performance of structural components. Tensile residual stresses are of particular concern due to their ability to cause significant degradation to the PWSCC resistance of structural materials. The contour method is a residual stress measurement technique capable of generating two dimensional maps of residual stress, which is particularly useful when applied to welds due to the complex residual stress distributions that generally result. The two-dimensional capability of the contour method enables detailed visualization of complex weld residual stress fields. This data can be used to identify locations and magnitude of tensile residual stress hot-spots. This paper provides a summary of the contour method and presents detailed results of contour method measurements made on the dissimilar metal weld region of pressurizer relief nozzles removed from the cancelled WNP-3 plant in the United States as part of the NRC/EPRI weld residual stress (WRS) program [1].

The Effect of Pipe Thickness on Residual Stresses due to Girth Welds

1982 ◽  
Vol 104 (3) ◽  
pp. 204-209 ◽  
Author(s):  
E. F. Rybicki ◽  
P. A. McGuire ◽  
E. Merrick ◽  
J. Wert
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Residual Stresses ◽  
304 Stainless Steel ◽  
Stress Distributions ◽  
Intergranular Stress Corrosion ◽  
Steel Pipes ◽  
Inner Surface ◽  
Girth Welds ◽  
Intergranular Stress Corrosion Cracking

This paper addresses the question of what effect the pipe thickness has on weld residual stresses in 304 stainless steel piping. Two diameters are considered. These are nominal 4-in. and 10-in. diameters. Four pipe wall thicknesses corresponding to schedules 10, 40, 80, and 160 are examined for each pipe. The focus is on residual stress distributions on the pipe inner surface because this is a primary site for intergranular stress corrosion cracking in 304 stainless steel pipes. The trends in residual stress values are toward more compressive stresses at the pipe inner surface for thicker pipes with the same nominal diameter. Residual axial stresses for the thick 10-in. schedule 160 pipe were found to be compressive while those for the thinner schedule 80 pipe were tensile. X-ray residual stress data for a 6-in-dia schedule 160 pipe fall between the results for the 4-in. and 10-in. schedule 160 pipes and support the findings of the study.

Revised Guidance on Residual Stresses in BS7910

2011 ◽  
Author(s):  
John Sharples ◽  
Peter Gill ◽  
Liwu Wei ◽  
Steve Bate
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Welded Joints ◽  
Stress Distributions ◽  
Metallic Structures ◽  
British Standard ◽  
Major Revision ◽  
Weld Residual Stress ◽  
Stress Profiles

A major revision of the British Standard BS7910 on “Guide to Methods for Assessing the Acceptability of Flaws in Metallic Structures” is being planned for issue in 2012. This paper provides an overview of the proposed revised guidance in relation to recommended weld residual stress profiles. As such, the paper is focussed on the proposed revised Annex Q of BS7910 which deals with residual stress distributions in as-welded joints.

Weld Residual Stresses and Their Treatment in Fracture and Fatigue Assessment

2004 ◽  
Author(s):  
P. Dong
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Crack Size ◽  
Stress Distributions ◽  
Fatigue Assessment ◽  
Stress Effects ◽  
Large Size ◽  
Girth Welds ◽  
Range Of Influence

Over the last decade, as more in-depth understanding of weld residual stresses is being achieved, particularly of their characteristic distributions in pressure vessel and piping components, the residual stress effects on stress intensities at welds are becoming better understood. In this paper, some of the important residual stress characteristics are first identified in the form of either “bending” dominated or “self-equilibrating” dominated types for girth welds. The applicability in other joint configurations in welded structures is then discussed, with a collection of validated residual stress distributions. The characterization of both “bending” and “self-equilibrating” types in residual stress distributions provides a consistent framework for stress intensity factor considerations in either fracture and fatigue assessment. The contribution of weld residual stresses to stress intensities at welds are shown to be in the form of K solutions under displacement controlled conditions. The “bending” type residual stresses provide a longer range of influence than “self-equilibrating” type in K solutions. The contribution of “self-equilibrating” type residual stresses to stress intensities is shown to be dominant when crack size is small, while the contribution of the “bending” type dominant for crack size up to a much large size with respect to wall thickness.

scholarly journals Residual Stress State of X65 Pipeline Girth Welds Before and After Local and Furnace Post Weld Heat Treatment

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Yao Ren ◽  
Anna Paradowska ◽  
Bin Wang ◽  
Elvin Eren ◽  
Yin Jin Janin
Keyword(s):  
Heat Treatment ◽  
Residual Stress ◽  
Residual Stresses ◽  
Outer Surface ◽  
Post Weld Heat Treatment ◽  
Pipe Length ◽  
Stress Profiles ◽  
Girth Welds ◽  
Welded Pipe ◽  
Weld Heat

This research investigated the effects of global (in other words, furnace-based) and local post weld heat treatment (PWHT) on residual stress (RS) relaxation in API 5L X65 pipe girth welds. All pipe spools were fabricated using identical pipeline production procedures for manufacturing multipass narrow gap welds. Nondestructive neutron diffraction (ND) strain scanning was carried out on girth welded pipe spools and strain-free comb samples for the determination of the lattice spacing. All residual stress measurements were carried out at the KOWARI strain scanning instrument at the Australian Nuclear Science and Technology Organization (ANSTO). Residual stresses were measured on two pipe spools in as-welded condition and two pipe spools after local and furnace PWHT. Measurements were conducted through the thickness in the weld material and adjacent parent metal starting from the weld toes. Besides, three line-scans along pipe length were made 3 mm below outer surface, at pipe wall midthickness, and 3 mm above the inner surface. PWHT was carried out for stress relief; one pipe was conventionally heat treated entirely in an enclosed furnace, and the other was locally heated by a flexible ceramic heating pad. Residual stresses measured after PWHT were at exactly the same locations as those in as-welded condition. Residual stress states of the pipe spools in as-welded condition and after PWHT were compared, and the results were presented in full stress maps. Additionally, through-thickness residual stress profiles and the results of one line scan (3 mm below outer surface) were compared with the respective residual stress profiles advised in British Standard BS 7910 “Guide to methods for assessing the acceptability of flaws in metallic structures” and the UK nuclear industry's R6 procedure. The residual stress profiles in as-welded condition were similar. With the given parameters, local PWHT has effectively reduced residual stresses in the pipe spool to such a level that it prompted the thought that local PWHT can be considered a substitute for global PWHT.

scholarly journals Predicting How Crack Tip Residual Stresses Influence Brittle Fracture

2002 ◽  
Author(s):  
Saeid Hadidimoud ◽  
Ali Mirzaee-Sisan ◽  
Chris E. Truman ◽  
David J. Smith
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Experimental Studies ◽  
Crack Tip ◽  
Distribution Model ◽  
Relative Importance ◽  
Local Approach ◽  
Weibull Parameters ◽  
Experimental Scatter ◽  
Crack Tip Blunting

A probability distribution model, based on the local approach to fracture, has been developed and used for estimating cleavage fracture following prior loading (or warm pre-stressing) in two ferritic steels. Although there are many experimental studies it is not clear from these studies whether the generation of local residual stress and/or crack tip blunting as a result of prior loading contribute to the enhancement in toughness. We first identify the Weibull parameters required to match the experimental scatter in lower shelf toughness of the candidate steels. Second we use these parameters in finite element simulations of prior loading on the upper shelf followed by unloading and cooling to lower shelf temperatures to determine the probability of failure. The predictions are consistent with experimental scatter in toughness following WPS and provide a means of determining the relative importance of the crack tip residual stresses and crack tip blunting. We demonstrate that for our steels the crack tip residual stress is the pivotal feature in improving the fracture toughness following WPS. The paper finally discusses these results in the context of the non-uniqueness and the sensitivity of the Weibull parameters.

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