Rational Limits of High-Low Misalignment in Girth Welds

2020 ◽  
Author(s):  
Banglin Liu ◽  
Yong-Yi Wang ◽  
Dan Jia ◽  
Steve Rapp
Keyword(s):  
Pipe Wall ◽  
Safety Margin ◽  
Bending Stress ◽  
Test Program ◽  
Acceptance Criteria ◽  
Element Analysis ◽  
Wide Range ◽  
Capacity Reduction ◽  
Girth Welds

Abstract High-low misalignment in girth welds introduces local bending stress and thus can potentially have detrimental effects on the stress capacity of girth welds. However, long-term pipeline service experience demonstrates that high levels of high-low misalignment do not always lead to reductions in the safety and integrity of pipelines. This paper discusses a PRCI-funded work that aimed to understand the impacts of misalignment on the integrity of girth welds and develop rational limits for misalignment for incorporation into existing standards. Two sets of recommendations were developed: (1) recommendations on the incorporation of rational limits for misalignment into workmanship criteria, and (2) recommendations on rational limits for misalignment for application in alternative flaw acceptance criteria, such that those in API 1104 Annex A and CSA Z662 Annex K. The recommendations for the workmanship criteria utilize extra weld reinforcement to compensate for stress capacity reduction due to misalignment. The recommendations consist of minimum values for key weld dimensions for a wide range of pipe wall thicknesses. The recommendations were developed based on a cross-weld tensile (CWT) test program and were validated using targeted finite element analysis (FEA). The recommendations for the application of the engineering critical assessment (ECA) procedures provide a maximum permissible misalignment level, up to which the ECA procedures produce sufficiently conservative flaw acceptance criteria without needing to correct for misalignment. The maximum permissible misalignment was based on comparisons between FEA and the API 1104 Annex A ECA procedures. A concept of a safety margin was introduced to quantify the conservatism built into the Annex A procedures and to derive a maximum allowable misalignment value.

Case Studies on ECA-Based Flaw Acceptance Criteria for Pipe Girth Welds Using BS 7910:2005

2007 ◽  
Author(s):  
Mohamad J. Cheaitani
Keyword(s):  
Case Studies ◽  
Pipe Wall ◽  
Single Point ◽  
Welding Residual Stress ◽  
Practical Case ◽  
Acceptance Criteria ◽  
Specific Level ◽  
Failure Assessment ◽  
Girth Welds ◽  
Selection Of

The use of an engineering critical assessment (ECA) approach to derive flaw acceptance criteria for pipe girth welds has become common practice. It allows the maximum tolerable size of weld flaws to be determined on a fitness-for-purpose basis, offering substantial advantages over the conventional workmanship approach. BS 7910:2005 is widely used to derive ECA-based flaw acceptance criteria for pipe girth welds. It offers a flexible assessment framework within the context of the well-established failure assessment diagram (FAD) approach. However, it can be relatively complex to apply and it may lead to assessments that are more conservative than codified pipeline-specific procedures. This paper illustrates, through practical case studies on assessing the significance of circumferential girth weld flaws, some of the options available to the user of BS 7910. The case studies cover the selection of the FAD (generalised or material-specific, with and without yield discontinuity), tensile properties (specified minimum or actual values); fracture toughness properties (single point CTOD values including δ0.2BL and δm, or full CTOD resistance R-curve), and welding residual stress (assumed to be uniform through the pipe wall with a yield strength magnitude, or considered to have a through-wall distribution associated with a specific level of welding heat input).

Stress Analysis of Lifting and Lowering-In Process

2014 ◽  
Author(s):  
Fan Zhang ◽  
Ming Liu ◽  
Yong-Yi Wang ◽  
William A. Bruce
Keyword(s):  
Vertical Plane ◽  
Ground Movement ◽  
Lateral Movement ◽  
Combined Stress ◽  
Acceptance Criteria ◽  
Element Analysis ◽  
Bending Stresses ◽  
Cross Country ◽  
Potential Damage

For typical cross-country pipelines not expected to experience ground movement hazards, the longitudinal stresses experienced during lifting and lowering-in are typically the highest that they experience in their entire service life. Vertical bending stresses are produced by the curvature created from the upward lifting forces of the sidebooms and the downward force of the pipe weight. Horizontal bending stresses are produced due to the lateral movement of the pipe when the pipe string is moved from its support position on the side of trench to the center of the trench. It is critical to limit the stresses during lifting and lowering-in so that potential damage to the pipeline is avoided. For pipelines constructed using an engineering critical assessment (ECA) based flaw acceptance criteria, stresses must be controlled below the limit established during the development of the flaw acceptance criteria. However, there is little in the way of formal guidance in current codes and standards for controlling stresses during the lifting and lowering-in process. This paper is part of a long-term effort being sponsored primarily by Pipeline Research Council International (PRCI) to develop general construction guidelines that can be used to manage lifting and lowering-in stresses during pipeline construction. In this paper, the stresses during lifting and lowering-in on normally flat terrain were studied. The component of stress due to bending in the horizontal plane was determined through an analytical method. The component of stress due to the bending in the vertical plane was studied by finite element analysis (FEA). The FEA determined the stresses under various profiles. Recommended lifting profiles in the format of lifting height ranges were developed. The combined stress was then determined from the two components. In addition, FEA was used to simulate the lifting and lowering-in process of a pipe string including a field side bend. The results show that the side bend produces a very slight increase in the stress level. More work is being performed to investigate various other scenarios of field and pipe string conditions.

scholarly journals Limitations on ACI Code Minimum Thickness Requirements for Flat Slab

2021 ◽  
Vol 7 (11) ◽  
pp. 1918-1932
Author(s):  
Bilal Ismaeel Abd Al-Zahra ◽  
Maitham Alwash ◽  
Ameer Baiee ◽  
Ali A. Shubbar
Keyword(s):  
Compressive Strength ◽  
Slab Thickness ◽  
Minimum Thickness ◽  
Element Analysis ◽  
Flat Slab ◽  
Flat Slabs ◽  
Wide Range ◽  
High Consistency ◽  
Panel Thickness

Reinforced concrete two-way flat slabs are considered one of the most used systems in the construction of commercial buildings due to the ease of construction and suitability for electrical and mechanical paths. Long-term deflection is an essential parameter in controlling the behavior of this slab system, especially with long spans. Therefore, this study is devoted to investigating the validation of the ACI 318-19 Code long-term deflection limitations of a wide range of span lengths of two-way flat slabs with and without drop panels. The first part of the study includes nonlinear finite element analysis of 63 flat slabs without drops and 63 flat slabs with drops using the SAFE commercial software. The investigated parameters consist of the span length (4, 5, 6, 7, 8, 9, and 10m), compressive strength of concrete (21, 35, and 49 MPa), the magnitude of live load (1.5, 3, and 4.5 kN/m2), and the drop thickness (0.25tslab, 0.5tslab, and 0.75tslab). In addition, the maximum crack width at the top and bottom are determined and compared with the limitations of the ACI 224R-08. The second part of this research proposes modifications to the minimum slab thickness that satisfy the permissible deflection. It was found, for flat slabs without drops, the increase in concrete compressive strength from 21MPa to 49MPa decreases the average long-term deflection by (56, 53, 50, 44, 39, 33 and 31%) for spans (4, 5, 6, 7, 8, 9, and 10 m) respectively. In flat slab with drop panel, it was found that varying drop panel thickness t2 from 0.25  to 0.75  decreases the average long-term deflection by (45, 41, 39, 35, 31, 28 and 25%) for span lengths (4, 5, 6, 7, 8, 9 and 10 m) respectively. Limitations of the minimum thickness of flat slab were proposed to vary from Ln/30 to Ln/19.9 for a flat slab without a drop panel and from Ln/33 to Ln/21.2 for a flat slab with drop panel. These limitations demonstrated high consistency with the results of Scanlon and Lee's unified equation for determining the minimum thickness of slab with and without drop panels. Doi: 10.28991/cej-2021-03091769 Full Text: PDF

Design Guideline and Acceptance Criteria for the Sag Bend Compression of Steel Catenary Riser

2009 ◽  
Author(s):  
Wei Ye ◽  
Michelle Zhang
Keyword(s):  
Design Guidelines ◽  
Gas Production ◽  
Outer Diameter ◽  
Bending Stress ◽  
Stress Strain ◽  
Acceptance Criteria ◽  
Design Guideline ◽  
Steel Catenary Riser ◽  
Nonlinear Strain ◽  
Wide Range

Although steel catenary riser (SCR) is an efficient riser concept for the deepwater oil and gas production, SCR on a Semi-submersible is susceptible to compression at the sag bend region that may lead to over stress under extreme environmental conditions such as 100-year and 1000-year return hurricane in Gulf of Mexico (GOM). It is one of the challenges to SCR design. The paper covers a wide range of SCRs, ranging from 6 inch to 20 inch outer diameter and including production and export SCRs, under the 100-year and 1000-year return hurricane conditions in GOM. Both linear and nonlinear analysis is performed. The non-dimensional compression and stress/strain coefficients are proposed, and they reveal excellent correlations between them and the compression force and bending stress/strain despite of the different riser size and weight. These coefficients can be used to determine the level of compression and bending stress/strain before the detailed and lengthy calculations, which are very useful as design guidelines. The acceptance criteria for GOM 100-year and 1000-year return hurricanes are discussed. It is recommended that for the nonlinear strain-based design the collapsed-based strain acceptance criteria are not conservative. More stringent nonlinear strain-based criteria are recommended, such as fracture mechanics analysis and accumulated strain analysis to ensure the integrity of the SCR during its life span.

Effect of shape imperfections on elastic stresses of U-bends subjected to in-plane moment

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
L.A. Krishna ◽  
A.R. Veerappan ◽  
S. Shanmugam
Keyword(s):  
Finite Element ◽  
Structural Integrity ◽  
Elastic Stress ◽  
Circular Cross Section ◽  
Bending Stress ◽  
Membrane Stress ◽  
Element Analysis ◽  
Content Type ◽  
Wide Range ◽  
Stress Components

PurposePrecise assessment of elastic stress is required in the field of fracture mechanics. While bending a straight pipe, the deformation of the circular cross section out of roundness called ovality and thinning are foreseeable. The ovality has a significant effect on the structural integrity of the pipe. The sole objective of this paper is to provide new analytical solutions to predict accurate elastic stress distribution at the median section of the U-bend, with deformities such as ovality and thinning when subjected to in-plane closing moment by using elastic finite element analysis.Design/methodology/approachThe quarter model of the U bend has been analysed by using ABAQUS. The elastic stress components included in this analysis are longitudinal bending stress, longitudinal membrane stress, circumferential bending stress and circumferential membrane stress. Based on finite element results, analytical elastic stress solutions are also provided for both longitudinal and circumferential stresses by using these stress components.FindingsAs the ovality has a significant effect, it is further included in the analytical solution. The thinning is not included since it has very little effect. Analytical stress solutions are provided for a wide range of bend characteristics to include ovality, mean radius and thickness.Originality/valueSignificance of ovality and thinning on elastic stress of U-bend has not been reported in the existing literature.

Precision and bias in quantitative EDS: ASTM results

1992 ◽  
Vol 50 (2) ◽  
pp. 1654-1655
Author(s):  
John J. Friel
Keyword(s):  
Stainless Steel ◽  
Quantitative Analysis ◽  
Mechanical Alloy ◽  
Dead Time ◽  
Test Program ◽  
Round Robin Test ◽  
Wide Range ◽  
American Society ◽  
Takeoff Angle ◽  
Standardless Analysis

Committee E-04 on Metallography of the American Society for Testing and Materials (ASTM) conducted an interlaboratory round robin test program on quantitative energy dispersive spectroscopy (EDS). The test program was designed to produce data on which to base a precision and bias statement for quantitative analysis by EDS. Nine laboratories were sent specimens of two well characterized materials, a type 308 stainless steel, and a complex mechanical alloy from Inco Alloys International, Inconel® MA 6000. The stainless steel was chosen as an example of a straightforward analysis with no special problems. The mechanical alloy was selected because elements were present in a wide range of concentrations; K, L, and M lines were involved; and Ta was severely overlapped with W. The test aimed to establish limits of precision that could be routinely achieved by capable laboratories operating under real world conditions. The participants were first allowed to use their own best procedures, but later were instructed to repeat the analysis using specified conditions: 20 kV accelerating voltage, 200s live time, ∼25% dead time and ∼40° takeoff angle. They were also asked to run a standardless analysis.

Modern prevention and active longevity programs on the basis of disruptive domestic technologies: positive experience and prospects for application

2020 ◽  
pp. 66-73
Author(s):  
A. Simonova ◽  
S. Chudakov ◽  
R. Gorenkov ◽  
V. Egorov ◽  
A. Gostry ◽  
...  
Keyword(s):  
Personalized Medicine ◽  
Early Detection ◽  
Laboratory Diagnostics ◽  
Positive Experience ◽  
Practical Application ◽  
Wide Range ◽  
Integrated Program ◽  
Long Term Experience ◽  
Early Detection And Prevention

The article summarizes the long-term experience of practical application of domestic breakthrough technologies of preventive personalized medicine for laboratory diagnostics of a wide range of socially significant non-infectious diseases. Conceptual approaches to the formation of an integrated program for early detection and prevention of civilization diseases based on these technologies are given. A vision of the prospects for the development of this area in domestic and foreign medicine has been formed.

To the 70th anniversary of World Meteorological Organization. Scientific and technical cooperation of Hydrometeorological Center of the USSR/Russia in the Programs of World Meteorological Organization

2020 ◽  
pp. 117-138
Author(s):  
S.V. Borshch ◽  
◽  
R.M. Vil’fand ◽  
D.B. Kiktev ◽  
V.M. Khan ◽  
...  
Keyword(s):  
Environmental Monitoring ◽  
High Efficiency ◽  
World Meteorological Organization ◽  
70Th Anniversary ◽  
Technical Level ◽  
Technical Cooperation ◽  
Wide Range

The paper presents the summary and results of long-term and multi-faceted experience of international scientific and technical cooperation of Hydrometeorological Center of Russia in the field of hydrometeorology and environmental monitoring within the framework of WMO programs, which indicates its high efficiency in performing a wide range of works at a high scientific and technical level. Keywords: World Meteorological Organization, major WMO programs, representatives of Hydrometeorological Center of Russia in WMO

Research on the Economic Organization Environmental Impact

2017 ◽  
Vol 68 (3) ◽  
pp. 599-601
Author(s):  
Dan Paul Stefanescu ◽  
Oana Roxana Chivu ◽  
Claudiu Babis ◽  
Augustin Semenescu ◽  
Alina Gligor
Keyword(s):  
Economic Activity ◽  
Economic Organization ◽  
Economic Activities ◽  
Environmental Implications ◽  
Minimal Impact ◽  
Wide Range ◽  
Material Environment ◽  
Negative Effect ◽  
Harmful Effects

Any economic activity carried out by an organization, can generate a wide range of environmental implications. Particularly important, must be considered the activities that have a significant negative effect on the environment, meaning those which pollute. Being known the harmful effects of pollution on the human health, the paper presents two models of utmost importance, one of the material environment-economy interactions balance and the other of the material flows between environmental factors and socio-economic activities. The study of these models enable specific conditions that must be satisfied for the economic processes friendly coexist to the environment for long term, meaning to have a minimal impact in that the residues resulting from the economic activity of the organization to be as less harmful to the environment.

Long-term Effects of Triazol Growth Regulators on Stem Elongation of Rhododendron and Kalmia

HortScience ◽  
1997 ◽  
Vol 32 (3) ◽  
pp. 436E-436
Author(s):  
Martin P.N. Gent
Keyword(s):  
Dose Response ◽  
Growth Regulator ◽  
Stem Elongation ◽  
Spray Application ◽  
Long Term Effects ◽  
Potted Plants ◽  
Response Coefficient ◽  
Wide Range ◽  
Second Year

The persistence of effects of paclobutrazol or uniconazol on stem elongation was determined for several years after large-leaf Rhododendron and Kalmia latifolia were treated with a single-spray application of these triazol growth-regulator chemicals. Potted plants were treated in the second year from propagation, and transplanted into the field in the following spring. The elongation of stems was measured in the year of application and in the following 2 to 4 years. Treatments with a wide range of doses were applied in 1991, 1992, or 1995. For all except the most-dilute applications, stem elongation was retarded in the year following application. At the highest doses, stem growth was inhibited 2 years following application. The results could be explained by a model of growth regulator action that assumed stem elongation was inversely related to amount of growth regulator applied. The dose response coefficient for paclobutrazol was less than that for uniconazol. The dose that inhibited stem elongation one-half as much as a saturating dose was about 0.5 and 0.05 mg/plant, for paclobutrazol and uniconazol, respectively. The dose response coefficient decreased exponentially with time after application, with an exponential time constant of about 2/year. The model predicted a dose of growth regulator that inhibited 0.9 of stem elongation immediately after application would continue to inhibit 0.5 of stem elongation in the following year.

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