An Evaluation Procedure for Crack Driving Forces in Mismatched Welds and its Applicability to ECA Analysis of Undermatched Clad Pipe Girth Welds

2014 ◽  
Author(s):  
Rodolfo F. de Souza ◽  
Claudio Ruggieri
Keyword(s):  
Structural Integrity ◽  
Driving Forces ◽  
Evaluation Procedure ◽  
Piping System ◽  
Large Set ◽  
Alloy 625 ◽  
Wide Range ◽  
Bending Load ◽  
Critical Flaw ◽  
Girth Welds

Structural integrity of submarine risers and flow lines transporting corrosive and aggressive hydrocarbons represents a key factor in operational safety of subsea pipelines. Advances in existing technologies favor the use of C-Mn steel pipelines (for example, API X65 grade steel) either clad or mechanically lined with a corrosion resistant alloy (CRA), such as Alloy 625, for the transport of corrosive hydrocarbons. However, while cost effective, specification of critical flaw sizes for their girth welds become more complex due to the dissimilar nature of these materials. In particular, effective fracture assessments of undermatched girth welds remain essential to determine more accurate acceptable flaw sizes for the piping system based upon engineering critical assessment (ECA) procedures. This work focuses on development of an evaluation procedure for the elastic-plastic crack driving force (as characterized by the J-integral) in pipeline girth welds with circumferential surface cracks subjected to bending load for a wide range of crack geometries and weld mismatch levels based upon the GE-EPRI framework. The study also addresses the effects of an undermatching girth weld on critical flaw sizes for a typical clad pipe employed in subsea flowlines having an Alloy 625 girth weld. The extensive 3-D numerical analyses provide a large set of solutions for J in cracked pipes and cylinders with mismatched girth welds while, at the same time, gaining additional understanding of the applicability of ECA procedures in welded cracked structural components.

Fitness-for-Service Fracture Assessments of Dissimilar Pipe Girth Welds Incorporating New Crack Driving Force Solutions

2014 ◽  
Author(s):  
Rodolfo F. de Souza ◽  
Claudio Ruggieri
Keyword(s):  
Driving Force ◽  
Large Scale ◽  
Structural Integrity ◽  
Numerical Solutions ◽  
Driving Forces ◽  
Limit Load ◽  
Assessment Procedure ◽  
Crack Driving Force ◽  
Alloy 625 ◽  
Girth Welds

The increasing demand for energy and natural resources has spurred a flurry of exploration and production activities of oil and natural gas in more hostile environments, including very deep water offshore production. Currently, structural integrity of submarine risers and flowlines conducting corrosive and aggressive hydrocarbons represents a key factor in operational safety of subsea pipelines. Advances in existing technologies favor the use of CMn steel pipelines (for example, API X65 grade steel) clad or mechanically lined with a corrosion resistant alloy (CRA), such as Alloy 625, for the transport of corrosive fluids. This work focuses on a fitness-for-service defect assessment procedure for strength mismatched welded components incorporating new crack driving force and limit load solutions. The study broadens the applicability of current evaluation procedures for J and CTOD which enter directly into structural integrity analyses and flaw tolerance criteria to provide a fairly comprehensive body of numerical solutions for crack driving forces in mismatched girth welds with circumferential surface cracks. This investigation also provides mismatch yield load solutions which are central to accurately predict failure load in strength mismatched structures subjected to large scale plasticity and ductile behavior. An approach is utilized to analyze the potential effects of the undermatching girth weld on critical flaw sizes for a typical lined pipe employed in subsea flowlines having a girth weld made of Alloy 625.

J and CTOD Estimation Procedure for Circumferentially Cracked Pipes Under Combined Bending and Internal Pressure

2011 ◽  
Author(s):  
Lui´s F. S. Parise ◽  
Claudio Ruggieri
Keyword(s):  
Internal Pressure ◽  
Structural Integrity ◽  
Biaxial Loading ◽  
Numerical Solutions ◽  
Driving Forces ◽  
Crack Depth ◽  
Bending Moment ◽  
Estimation Procedure ◽  
Wide Range ◽  
Bending Load

This work provides an estimation procedure to determine the J-integral and CTOD for pipes with circumferential surface cracks subjected to combined bending load and internal pressure for a wide range of crack geometries and material (hardening) based upon fully-plastic solutions. The present investigation broadens the applicability of current evaluation procedures for J and CTOD which enter directly into structural integrity analyses and flaw tolerance criteria. Extensive 3-D nonlinear analyses of circumferentially cracked pipes with surface flaws having different crack depth (a) over pipe wall thickness (t) ratios and varying crack length for different strain hardening properties provide the dimensionless parameters relating the elastic-plastic crack-tip driving forces with the applied (remote) bending moment and internal pressure. The investigation provides a fairly comprehensive body of numerical solutions for J and CTOD in circumferentially cracked pipes subjected to biaxial loading.

Fully-Plastic J and CTOD Solutions for Pipes With Circumferential Surface Cracks Subjected to Combined Bending and Tension

2011 ◽  
Author(s):  
Lui´s F. S. Parise ◽  
Claudio Ruggieri
Keyword(s):  
Material Properties ◽  
Tensile Load ◽  
Estimation Procedure ◽  
Large Set ◽  
J Integral ◽  
Surface Cracks ◽  
Defect Assessment ◽  
Wide Range ◽  
Bending Load ◽  
Assessment Procedures

This work provides an estimation procedure to determine the J-integral and CTOD for pipes with circumferential surface cracks subjected to combined bending and tensile load for a wide range of crack geometries and material (hardening) based upon fully-plastic solutions. A summary of the methodology upon which J and CTOD are derived sets the necessary framework to determine nondimensional functions h1 and h2 applicable to a wide range of crack geometries and material properties characteristic of structural, pressure vessel and pipeline steels. The extensive nonlinear, 3-D numerical analyses provide a large set of solutions for J and CTOD which enters directly into fitness-for-service (FFS) analyses and defect assessment procedures of cracked pipes and cylinders subjected to bending load.

J and CTOD Estimation Procedure for Circumferentially Cracked Pipes Based on Fully-Plastic Solutions

2010 ◽  
Author(s):  
Mario S. G. Chiodo ◽  
Claudio Ruggieri
Keyword(s):  
Pressure Vessel ◽  
Material Properties ◽  
Estimation Procedure ◽  
Large Set ◽  
J Integral ◽  
Surface Cracks ◽  
Defect Assessment ◽  
Wide Range ◽  
Bending Load ◽  
Assessment Procedures

This work provides an estimation procedure to determine the J-integral and CTOD for pipes with circumferential surface cracks subjected to bending load for a wide range of crack geometries and material (hardening) based upon fully-plastic solutions. A summary of the methodology upon which J and CTOD are derived sets the necessary framework to determine nondimensional functions h1 and h2 applicable to a wide range of crack geometries and material properties characteristic of structural, pressure vessel and pipeline steels. The extensive nonlinear, 3-D numerical analyses provide a large set of solutions for J and CTOD which enters directly into fitness-for-service (FFS) analyses and defect assessment procedures of cracked pipes and cylinders subjected to bending load.

Bull Run Fossil Plant Main Steam Piping Creep Evaluation

2007 ◽  
Author(s):  
Darryl A. Rosario ◽  
Blaine W. Roberts ◽  
M. Scott Turnbow ◽  
Salah E. Azzazy
Keyword(s):  
Power Plants ◽  
Structural Integrity ◽  
Piping System ◽  
Fossil Plant ◽  
Contributing Factors ◽  
Engineering Consulting ◽  
Commercial Operation ◽  
Burning Coal ◽  
Girth Welds ◽  
Main Steam

Bull Run Unit 1, rated at 950 MW, is the first of four fossil supercritical power plants at TVA; the unit went into commercial operation in 1967. The boiler, built by Combustion Engineering (CE), has a radiant reheat twin divided furnace with tangential-fired burners for burning coal. The unit’s maximum continuous rating (MCR) is 6,400,000 lbs/hr of main steam flow, with a design temperature of 1003°F and pressure of 3840 psig. Through the end of November 2003, the unit had a total of 589 cumulative starts and 253,343 operating hours. In 1986 TVA located and repaired extensive cracking in the mixing link headers (27 of 32 saddle welds cracked) downstream of the superheater outlet headers. Visible sag was also noted at the mid-span of the mixing headers. Since that time through 2003, additional cracking of girth welds in the mixing link headers was discovered, followed by cracking in the main piping girth welds at the connections to the mixing headers and at one of the connections to the turbine. From 1988 through 2003 several elastic analyses which were performed were unable to explain the observed girth weld cracking and sagging in the piping. In October 2003, TVA contracted with Structural Integrity Associates (SI) and BW Roberts Engineering Consulting to perform elastic and creep analyses of the Bull Run main steam piping system to determine the most likely contributing factors to noticeable creep sagging and cracking problems in the mixing header link piping and main steam piping girth welds, and, to develop recommendations to mitigate additional cracking and creep/sagging. The evaluations concluded that improper hanger sizing along with longer-term hanger operational problems (non-ideal loads/travel, topped/bottomed out hangers) contributed to the observable creep sagging and girth weld cracking. The elastic and creep piping analyses performed to address these issues are described in this paper.

A FAD-Based Procedure for Defect Assessments of Welded Structures Including Effects of Weld Strength Mismatch: Micromechanics Approach and Application to Pipeline Girth Welds

2008 ◽  
Author(s):  
Gustavo H. B. Donato ◽  
Claudio Ruggieri
Keyword(s):  
Structural Integrity ◽  
Driving Forces ◽  
Pipeline Steel ◽  
Crack Tip ◽  
Weld Strength ◽  
Homogeneous Material ◽  
Fracture Parameter ◽  
Integrity Assessment ◽  
Girth Welds ◽  
Assessment Problems

ECA procedures of crack-like defects based upon the FAD philosophy have undergone extensive developments in the past decade to form the basis for industrial codes and guidelines for structural integrity assessments. However, the application of these procedures in welded structural components with mismatch in tensile properties between the weld and base metal remains a potential open issue. Weld strength mismatch may significantly alter the crack-tip driving forces, such as J and CTOD, thereby producing crack-tip stresses quite different than the fields that arise in corresponding homogeneous material. Weld strength mismatch also affects the plastic collapse load for the structural component which further complicates the interplay between fracture and plastic instability before gross yield section takes place. This work describes the development of a microme-chanics-based FAD methodology building upon a local fracture parameter, characterized by the Weibull stress (σw), to incorporate the effects of weld strength mismatch on crack-tip driving forces. As a further refinement, the study also addresses an exploratory application of a limit load analysis including effects of weld strength mismatch to correct the loading trajectory incorporated into the FAD procedure. Fracture testing of girth welds obtained from an API X80 pipeline steel provide the data needed to validate the proposed modified FAD procedure in failure predictions. Such an application serves as a prototype for a wide class of integrity assessment problems involving the effects of weld strength mismatch.

scholarly journals A developmentally descriptive method for quantifying shape in gastropod shells

2020 ◽  
Vol 17 (163) ◽  
pp. 20190721
Author(s):  
J. Larsson ◽  
A. M. Westram ◽  
S. Bengmark ◽  
T. Lundh ◽  
R. K. Butlin
Keyword(s):  
Empirical Studies ◽  
Three Dimensional ◽  
Shell Shape ◽  
Large Set ◽  
Littorina Saxatilis ◽  
Shape Variation ◽  
Gastropod Shell ◽  
Geometric Morphometric ◽  
Wide Range ◽  
Descriptive Method

The growth of snail shells can be described by simple mathematical rules. Variation in a few parameters can explain much of the diversity of shell shapes seen in nature. However, empirical studies of gastropod shell shape variation typically use geometric morphometric approaches, which do not capture this growth pattern. We have developed a way to infer a set of developmentally descriptive shape parameters based on three-dimensional logarithmic helicospiral growth and using landmarks from two-dimensional shell images as input. We demonstrate the utility of this approach, and compare it to the geometric morphometric approach, using a large set of Littorina saxatilis shells in which locally adapted populations differ in shape. Our method can be modified easily to make it applicable to a wide range of shell forms, which would allow for investigations of the similarities and differences between and within many different species of gastropods.

Using CFD to Enhance the Preliminary Design of High-Pressure Steam Turbines

2013 ◽  
Author(s):  
Juri Bellucci ◽  
Federica Sazzini ◽  
Filippo Rubechini ◽  
Andrea Arnone ◽  
Lorenzo Arcangeli ◽  
...  
Keyword(s):  
High Pressure ◽  
Steam Turbine ◽  
Design Tool ◽  
Tip Clearance ◽  
Large Set ◽  
Preliminary Design ◽  
Steam Turbines ◽  
High Pressure Steam ◽  
Wide Range ◽  
Pressure Steam

This paper focuses on the use of the CFD for improving a steam turbine preliminary design tool. Three-dimensional RANS analyses were carried out in order to independently investigate the effects of profile, secondary flow and tip clearance losses, on the efficiency of two high-pressure steam turbine stages. The parametric study included geometrical features such as stagger angle, aspect ratio and radius ratio, and was conducted for a wide range of flow coefficients to cover the whole operating envelope. The results are reported in terms of stage performance curves, enthalpy loss coefficients and span-wise distribution of the blade-to-blade exit angles. A detailed discussion of these results is provided in order to highlight the different aerodynamic behavior of the two geometries. Once the analysis was concluded, the tuning of a preliminary steam turbine design tool was carried out, based on a correlative approach. Due to the lack of a large set of experimental data, the information obtained from the post-processing of the CFD computations were applied to update the current correlations, in order to improve the accuracy of the efficiency evaluation for both stages. Finally, the predictions of the tuned preliminary design tool were compared with the results of the CFD computations, in terms of stage efficiency, in a broad range of flow coefficients and in different real machine layouts.

Performance of a Near Shore Oscillating Wave Surge Converter With Variable Flap Configurations in Various Sea Conditions

2021 ◽  
Author(s):  
Landon Sugar ◽  
Faete Filho ◽  
Tarek Abdel-Salam ◽  
Michael Muglia ◽  
Kurabachew Duba
Keyword(s):  
Wave Energy ◽  
Structural Integrity ◽  
Specific Reference ◽  
Wave Forces ◽  
Extreme Wave ◽  
Wide Range ◽  
Near Shore ◽  
Wave States ◽  
Pass Through ◽  
Survival Mode

Abstract Oscillating Wave Surge Converters (OWSCs) are designed to enter survival mode during extreme wave conditions where they forego the opportunity to extract energy to preserve structural integrity. While this is a good tradeoff, it is important that OWSC technology progresses to a point where energy is constantly extracted as long as waves are present. This work addresses the need for an OWSC that can extract wave energy in a wide range of sea conditions while minimizing structural overloading by regulating the fluid-structure interaction. The OWSC being studied here was conceptually designed and patented by researchers at NREL. It consists of a flap face that resembles household blinds, where the flaps can be opened or closed to accommodate the sea conditions. The performance of this variable geometry OWSC in various, shallow wave states was studied in two numerical modeling programs. Of particular interest were the flap’s hydrodynamic coefficients and potential power generation at a specific reference site. This configuration was predicted to mitigate wave forces by allowing some of the wave energy to pass through the device, thus preserving its structural integrity.

scholarly journals Supplier-initiating risk management behaviour and supply-side resilience: the effects of interpersonal relationships and dependence asymmetry in buyer-supplier relationships

2020 ◽  
Vol 40 (7/8) ◽  
pp. 971-995
Author(s):  
Yiyi Fan ◽  
Mark Stevenson ◽  
Fang Li
Keyword(s):  
Risk Management ◽  
Interpersonal Relationships ◽  
Supply Side ◽  
Large Set ◽  
Supplier Relationships ◽  
Content Type ◽  
Management Behaviour ◽  
Wide Range ◽  
Dependence Asymmetry ◽  
The Relationship

PurposeThe aim of the study is to explore how two dimensions of interpersonal relationships (i.e. size and range of relationships) affect supplier-initiating risk management behaviours (SIRMB) and supply-side resilience. Further, the study aims to explore the moderating role of dependence asymmetry.Design/methodology/approachNine hypotheses are tested based on a moderated mediation analysis of survey data from 247 manufacturing firms in China. The data are validated using a subset of 57 attentive secondary respondents and archival data.FindingsSIRMB positively relates to supply-side resilience. Further, SIRMB mediates the positive relationship between range and supply-side resilience, and this relationship is stronger at lower levels of dependence asymmetry. Yet, although dependence asymmetry positively moderates the relationship between range and SIRMB, it negatively moderates the relationship between size and SIRMB. We did not, however, find evidence that size has a conditional indirect effect on supply-side resilience through SIRMB.Practical implicationsManagers in buying firms can incentivise SIRMB to enhance supply-side resilience by developing a diverse rather than a large set of interpersonal relationships with a supplier. This might include allocating particular employees with a wide range of contacts within a supplier to that relationship, while it may be necessary to adopt different networking strategies for different supplier relationships. Firms in a highly asymmetrical relationship may seek to raise supplier expectations about the necessity to initiate risk management behaviour or look to change the dynamic of the relationship by managing contracts for fairness.Originality/valueNew knowledge on SIRMB as a mediating variable underpinning the relationship between interpersonal relationships and supply-side resilience is provided; and empirical evidence on the opposing moderation effect of dependence asymmetry is presented.

Sign in / Sign up

Export Citation Format

Share Document