Reduction in Stresses Shown in Piping Programs in Large Diameter Pipe Branch Connections by Applying Flexibilities Computed by Shell Finite Element Analysis

2004 ◽  
Author(s):  
Robert A. Robleto
Keyword(s):  
Finite Element Analysis ◽  
Large Diameter ◽  
Piping System ◽  
Bending Moments ◽  
Straight Pipe ◽  
Element Analysis ◽  
Large Diameter Pipe ◽  
Diameter Pipe ◽  
Piping Systems ◽  
Shell Finite Element

When designing branch connections in low pressure large diameter piping systems as in Figure 1, thicker is not always better. The flexibility factors in ASME B31.3 1 for branch connections do not assist the designer in taking credit for flexibility that may exist in a large diameter intersection. Since the stress intensification factors (SIFs) are relatively high for large diameter piping, many stub-in branch connections will require a pad to meet the code displacement stress limits. In an ASME B31.3 Piping analysis the stiffness of the branch connections is considered to be as stiff as a straight piece of pipe modeled as a beam. This is a simplifying assumption that can lead to expensive conservatism for the component and possibly non-conservatism for nearby equipment especially when large diameter pipe is considered. Branch connection flexibility is often negligible when compared with piping flexibility of straight pipe perpendicular to the deflection and bends which can ovalize under in-plane bending moments. However, studies at KBR show branch connections in large diameter pipe can contribute significant flexibility to a close coupled piping system.

Development and Application of Large Three-Way Hot Tapping Fittings

2004 ◽  
Author(s):  
William Alfons Jarvis
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
High Pressure ◽  
Large Diameter ◽  
Branch Ratio ◽  
Design Codes ◽  
Element Analysis ◽  
Piping Systems ◽  
Current Design ◽  
Shell Finite Element

Background on the development and application of high pressure “large branch ratio” three way tee style hot tapping and plugging fittings on large diameter (16”–54”) pipelines and pressure piping systems in Canada. Examines the limitations and problems in current design codes, for large ratio branch connections, and the good engineering practiced applied based on simple shell finite element analysis.

Creep Life Simulation and Assessment of High Temperature Piping Systems and Components

2012 ◽  
Author(s):  
Brian Rose ◽  
James Widrig
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
High Temperature ◽  
Creep Behavior ◽  
Material Behavior ◽  
Piping System ◽  
Remaining Life ◽  
Creep Life ◽  
Element Analysis ◽  
Piping Systems

High temperature piping systems and associated components, elbows and bellows in particular, are vulnerable to damage from creep. The creep behavior of the system is simulated using finite element analysis (FEA). Material behavior and damage is characterized using the MPC Omega law, which captures creep embrittlement. Elbow elements provide rapid yet accurate modeling of pinching of piping, which consumes a major portion of the creep life. The simulation is used to estimate the remaining life of the piping system, evaluate the adequacy of existing bellows and spring can supports and explore remediation options.

Simplified Seismic Response Analysis Method Using Reduced Model of Piping System

2018 ◽  
Author(s):  
Michiya Sakai ◽  
Ryuya Shimazu ◽  
Shinichi Matsuura ◽  
Ichiro Tamura
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Seismic Response ◽  
Degrees Of Freedom ◽  
Response Analysis ◽  
Piping System ◽  
Element Analysis ◽  
Mass System ◽  
Piping Systems ◽  
Low Degrees

In the seismic response analysis of piping systems, finite element analysis is performed with analysis method guidelines [1]–[4] established based on benchmark analysis. However, since it takes a great deal of effort to carry out finite element analysis, a simplified method to analyze the seismic response of complex piping systems is required. In this research, we propose a method to reduce an equivalent spring-mass system model with low degrees of freedom, which can take into account the main mode of the complicated piping system. Simplified seismic evaluation is carried out using this spring mass system model with low degrees of freedom, and the accuracy of response evaluation is confirmed by comparison with finite element analysis.

Elastic-Plastic Analysis of Thick-Walled Toroidal Pressure Vessels

2008 ◽  
Author(s):  
R. Adibi-Asl
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Three Dimensional ◽  
Pressure Vessels ◽  
Toroidal Shell ◽  
Piping System ◽  
Straight Pipe ◽  
Element Analysis ◽  
Process Industries ◽  
Piping Systems

Piping systems in process industries and nuclear power plants include straight pipe runs and various fittings such as elbows, miter bends etc. Elbows and bends in piping systems provide additional flexibility to the piping system along with performing the primary function of changing the direction of fluid flow. Distinctive geometry of these toroidal shell components result in a structural behavior different from straight pipe. Hence, it would be useful to predict the behavior of these components with acceptable accuracy for design purposes. Analytical expressions are derived for stresses set up during loading and unloading in a toroidal shell subjected to internal pressure. Residual stresses in the component are also evaluated. The proposed solutions are then compared with three-dimensional finite element analysis at different locations including intrados, extrados and flanks.

Stress Intensification Factor for Large Diameter Welding Tee Connections

2015 ◽  
Author(s):  
Sadjad Ranjbaran ◽  
Akbar Daneshvar Ghalelar
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Large Diameter ◽  
Piping System ◽  
Bending Moments ◽  
Straight Pipe ◽  
Butt Welds ◽  
Beam Elements ◽  
Stress Intensification Factor ◽  
Fatigue Characteristics

Stress Intensification Factors (SIFs) are factors relating to fatigue characteristics of piping components. SIF is fatigue correlation which compares fatigue life of a typical piping component such as a tee and elbow to the reference fatigue life, that is girth butt welds in straight pipe subjected to bending moments. In order to calculate localized stress of such piping component, above mentioned figured out SIF shall be multiplied by nominal stress. ASME B31 contains several formulas for stress intensification factors considering limitation that those formulas are valid only for D/T≤100 (diameter to thickness). Extending the valid range mentioned in ASME B31 this paper is dedicated to SIF calculation for D/T≤100 and also for D/T>100 by utilizing Finite Element Analyzing (FEA) for welding tee. The computed SIF for D/T>100 welding tee can now be placed to typical pipe stressing program which analyzes piping system using beam elements. In addition, this paper investigates the effect of Rx (the magnitude of corner radius of shoulder at branch) on SIF of Welding Tee Connections.

Development of Acceptance Criteria for Mild Ripples in Pipeline Field Bends

2002 ◽  
Author(s):  
M. J. Rosenfeld ◽  
James D. Hart ◽  
Nasir Zulfiqar ◽  
Richard W. Gailing
Keyword(s):  
Oil And Gas ◽  
Large Diameter ◽  
High Yield ◽  
Concentration Effects ◽  
Element Analysis ◽  
Industry Standards ◽  
Diameter Pipe ◽  
The Subject ◽  
Shell Finite Element ◽  
Damage Rule

Field bends in large diameter pipe are routinely used in the construction of oil and gas pipelines. Mild ripples along the intrados are often unavoidable where such bends have a high D/t or high yield strength. Present regulations and industry standards differ in their treatment of mild ripples, consequently, the acceptance of such features has been heretofore inconsistent. A review of prior work on the subject was undertaken. Shell finite element analysis was then used to estimate the effect of ripple magnitude and spacing on stresses due to pressure and bending. Stress concentration effects were used with a suitable fatigue damage rule to estimate the effect of ripple parameters on service life. Results were benchmarked against the available test data.

Dealing With Heavy Loads in Large Diameter Piping

2012 ◽  
Author(s):  
Hector Rojas ◽  
Andrey Gutkovsky
Keyword(s):  
Large Diameter ◽  
Operating Conditions ◽  
Configuration Design ◽  
Piping System ◽  
Flow Conditions ◽  
Element Analysis ◽  
Piping Systems ◽  
Molten Sulfur ◽  
Heavy Loads

It is common in a refinery that some piping systems have to handle several flow conditions. However, when a new proposed condition implies the filling of an existing 68″ (1727 mm) line with molten Sulfur, which was initially designed for gas operation, a well thought engineering case study is required to guarantee that no damage will occur under the new operating conditions. This paper covers the procedures employed to qualify the integrity of a 68″ (1727 mm) piping system, initially designed to carry Sulfur vapors and required to handle occasional filling with molten Sulfur due to operational demands. The procedures of reviewing the initial configuration, design of modifications and reinforcements to the piping system and the use of Finite Element Analysis (FEA) in order to qualify several unique support configurations are explained in this paper.

Stress of Large Diameter Piping System Shoe Support

2017 ◽  
Author(s):  
Sadjad Ranjbaran ◽  
Akbar Daneshvar Ghalelar
Keyword(s):  
Failure Modes ◽  
Large Diameter ◽  
Estimation Method ◽  
Beam Theory ◽  
Local Stress ◽  
Accurate Estimation ◽  
Piping System ◽  
Element Analysis ◽  
Piping Systems ◽  
Applied Design

As codes and standards employ the beam theory to evaluate stress in piping systems, large diameter piping is therefore outside the domain of these codes and standards. To investigate any failure modes in these piping systems, more general codes such as ASME Sec. VIII Div.2 must be used. Research has shown that estimating local stress is important near the shoe support tip especially for large diameter piping systems and aboveground pipelines. To evaluate protection against local failure under an applied design load, a more accurate estimation method of ASME Sec. VIII Div.2, part 5 is applied by using elastic-plastic stress analysis procedures. For this purpose, finite element analysis is carried out along with distributed gravity loading and design pressure. Furthermore, parametric FEA studies are conducted on the effect of the ratio of pipe diameter to thickness, as well as the width and wrap angle of shoe support on the local stress of shoe support. The FEA results have been compared to semi-empirical formula for local stress in shoe support developed by AWWA standard.

Vibration Behavior and Fatigue Strength of Mocked-Up Piping System

1997 ◽  
Vol 119 (3) ◽  
pp. 343-350 ◽  
Author(s):  
M. Hayashi ◽  
I. Tanaka ◽  
K. Iida ◽  
F. Matsuda ◽  
M. Sato
Keyword(s):  
Fatigue Strength ◽  
Welded Joint ◽  
Stress Amplitude ◽  
Large Diameter ◽  
Small Diameter ◽  
Piping System ◽  
Large Diameter Pipe ◽  
Four Point Bending ◽  
Nominal Diameter ◽  
Diameter Pipe

For the purpose of investigating vibration characteristics and fatigue strength of a socket-welded joint, a piping system was mocked-up by assembling a straight pipe of 350 mm nominal diameter and a long pipe of 20 mm nominal diameter consisting of straight pipes and elbows. The one end of the small-diameter piping is connected to the large-diameter pipe at its longitudinal midpoint by socket welding, and the rest is supported at several supporting points, the locations of which are changed as an experimental parameter. The materials of the small-diameter piping are carbon and stainless steels. The small-diameter piping was subjected to nearly resonant vibration with the frequency of about 11 Hz by a sinusoidal vibration load applied to the large-diameter pipe. The vibrating displacement amplitude measured on the actual piping was basically 0.05 mm in resonant condition; but the displacement was changed to obtain an S-N curve for the socket-welded joint in the fatigue life range of 104 to 107 cycles. In the mocked-up specimens, fatigue cracks were initiated from the toe of the socket-fillet welds at higher stress amplitude, but from the fillet root at lower stress amplitude. Comparative fatigue tests of straight shape socket-welded specimens fabricated with 20 mm nominal diameter pipe of the same material as used in the mocked-up specimen were carried out under four-point bending condition. The fatigue strength of the socket-welded joint in the mocked-up specimen was about 15 percent lower than that of the simple specimen fatigued by four-point bending load. The reason for this difference is probably due to the triaxial stress condition and three-dimensional restraint condition. The strain gage measurement showed that the shear stress was about 40 percent of the bending stress in the case of the mockedup specimen. In addition, vibration tests of the piping system showed good agreement between experimental and analytical results of vibration behavior.

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