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.

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.

Buckling Resistance of Large Diameter Spiral Welded Linepipe

2004 ◽  
Author(s):  
Tom Zimmerman ◽  
Chris Timms ◽  
Jueren Xie ◽  
James Asante
Keyword(s):  
Oil And Gas ◽  
Weld Seam ◽  
Large Diameter ◽  
Ground Movement ◽  
Finite Element Analyses ◽  
Line Pipe ◽  
Diameter Pipe ◽  
Buckling Resistance ◽  
Analytical Research ◽  
Full Scale Tests

This paper contains the results of an experimental and analytical research program to determine the compressive buckling resistance of large-diameter, spiral-welded linepipe. Buckling resistance is important for pipe intended for service in Arctic, oil and gas pipeline systems, where pipes may be subjected to high bending strains caused by various ground movement events. The experimental work consisted of four full-scale tests of 30-inch (762 mm) diameter pipe subjected to various combinations of internal pressure, axial force and bending. The pipe specimens were fabricated using two material grades (X70 and X80) and two D/t ratios (82 and 48). Finite element analyses of the four tests were conducted to develop a better understanding of specimen behavior. The results suggest that spiral welded linepipe is as good as longitudinally welded line pipe in terms of buckling capacity. The spiral weld seam was in no way detrimental to the pipe performance.

Modal Reduction Technique for Predicting the Onset of Chaotic Behavior due to Lateral Vibrations in Drillstrings

2015 ◽  
Vol 137 (2) ◽  
Author(s):  
Kathira Mongkolcheep ◽  
Annie Ruimi ◽  
Alan Palazzolo
Keyword(s):  
Finite Element ◽  
Oil And Gas ◽  
Chaotic Behavior ◽  
Large Diameter ◽  
Operating Conditions ◽  
Dynamical Analysis ◽  
Computational Time ◽  
Element Formulation ◽  
Element Analysis ◽  
Lateral Vibrations

Drillstrings used for oil and gas exploration and extraction consist of a drillpipe (slender columns on the order of 3–5 km long), drill collars (DCs) (thick-walled large-diameter pipes), stabilizers (cylindrical elements with short sections and diameter near that of the borehole), and a rock-cutting tool that uses rotational energy to penetrate the soil. Several types of vibrations ensue from these motions and play a major role in added costs resulting from unforeseen events such as abandoning holes, replacing bits, and fishing severed bottom-hole assemblies (BHAs). It is thus of critical importance to understand, predict, and mitigate the severe vibrations experienced by drillstrings and BHA to optimize drilling time while lowering fuel consumption and related emissions of NOX and/or other pollutants. In this paper, we present a dynamical analysis of the behavior of drillstrings due to the violent lateral vibrations (LVs) DCs may experience as a result of rotating drillstrings. The behavior is represented by a system of two coupled nonlinear ordinary equations that are integrated numerically with a finite element analysis based on Timoshenko beam (TB) formulation combined to a modal condensation technique to reduce the computational time. Various nonlinear dynamical analysis tools, such as frequency spectrum, Poincaré maps, bifurcation diagrams, and Lyapunov exponents (LE), are used to characterizing the response. The DC section between two stabilizers is essentially modeled as a Jeffcott rotor with nonlinearity effects included. The model builds on two earlier models for the finite element formulation and the treatment of chaotic vibrations. Nonlinearity appears in the form of drillstring/borehole contact force, friction, and quadratic damping. The DC flexibility is included to allow investigation of bending modes. The analysis takes into account the length of time to steady state, number of subintervals, presence of rigid body modes, number of finite elements, and modal coordinates. Simulations results indicate that by varying operating conditions, a spectrum of behaviors from periodic to chaotic may be observed.

Inner Pressure/Bending Creep Test on Circumferentially Welded Large Diameter Pipe of Grade 122 Steel: Failure Life Prediction

2015 ◽  
Author(s):  
Yukio Takahashi ◽  
Satoshi Nishinoiri ◽  
Masatsugu Yaguchi
Keyword(s):  
Life Prediction ◽  
Power Plants ◽  
Large Scale ◽  
Large Diameter ◽  
Element Analysis ◽  
Circumferential Welds ◽  
Deformation And Failure ◽  
Inner Pressure ◽  
Diameter Pipe ◽  
Failure Life

Estimation of failure lives for welded joints in piping made of creep strength enhanced ferritic steel is of great importance for ensuring safe and sound operation of ultra-supercritical fossil power plants using this type of material. As a part of the various efforts for developing the procedure meeting this need, a large scale pipe test was performed on grade 122 pipe with circumferential welds, in order to grasp its fracture behavior as well as its predictability. Finite element analysis as well as damage calculation were performed on this test. By using creep strain equations, as well as failure criterion newly developed for this material and welded joint, both creep deformation and failure life were successfully predicted with reasonable accuracy.

Use of Finite Element Analysis for Stud Pre-Tension Determination of Large Diameter Integral Flanges With Ring Joint Gaskets

2010 ◽  
Author(s):  
Upali Panapitiya ◽  
Haoyu Wang ◽  
Syed Jafri ◽  
Paul Jukes
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Oil And Gas ◽  
Large Diameter ◽  
Three Dimensional ◽  
Oil And Gas Industry ◽  
Element Analysis ◽  
Axial Forces ◽  
Three Dimensional Finite Element

Large diameter integral steel flanges are widely used in many applications in the oil and gas industry. The flanges of nominal pipe sizes, 26-inch and above with ring-joint gaskets as specified in ASME B 16.47 Standard, are used in the offshore applications for the transportation of oil and gas from production facilities. These pipelines require flanged connections at end terminations, mid-line tie-ins and expansion loops. The conventional design of large diameter steel flanges is based on one-dimensional analytical methods similar to the procedure in ASME VIII Boiler and Pressure Vessel Code, Division 1 Appendix 2. The effects of axial forces and bending moments are approximated by calculating an equivalent pressure. This usually results in conservative designs for the large flanges because it estimates the required stud pre-tension based on the assumption that the gasket will be unloaded entirely to a minimum stress, whereas only a small section of the gasket is subjected to low stress. This technical paper presents the quasi-static, nonlinear, and three-dimensional finite element models of large diameter steel flanged joint for the determination of stud pre-tension and change of stud tension under various loading conditions. The finite element analysis results are compared with the results obtained by using the equivalent pressure method and flange “Joint Diagram”.

Buckling of Ring Stiffened Pontoons of Floating Roofs in Aboveground Oil Storage Tanks

2007 ◽  
Author(s):  
Shoichi Yoshida ◽  
Kazuhiro Kitamura
Keyword(s):  
Large Diameter ◽  
Bending Moment ◽  
Bottom Plate ◽  
Storage Tanks ◽  
Element Analysis ◽  
Linear Elastic ◽  
Structural Problems ◽  
Oil Storage ◽  
Bifurcation Buckling ◽  
Shell Finite Element

The 2003 Tokachi-Oki earthquake caused severe damage to oil storage tanks due to liquid sloshing. Six single-deck floating roofs had experienced structural problems as evidenced by sinking failure in large diameter tanks at the refinery in Tomakomai, Japan. The pontoon of floating roof might be buckled due to circumferential bending moment during the sloshing. The content in the tank was spilled on the floating roof from small failures which might be caused in the lap-welded joints or in the stress concentrated parts of the pontoon bottom plate by the buckling. Then the floating roof began to lose buoyancy and submerged into the content slowly. The failure of the roof expanded gradually in the sinking process. It is presumed that the initial small failures were caused by the elastic buckling of the pontoon due to circumferential bending moment. In this paper, the buckling strength of the pontoon is presented using axisymmetric shell finite element analysis. Linear elastic bifurcation buckling analyses are carried out and the buckling characteristics of ring stiffened pontoons are investigated.

Lower Bound Buckling Load of a Floating Roof Pontoon

2010 ◽  
Author(s):  
Shoichi Yoshida
Keyword(s):  
Finite Element ◽  
Lower Bound ◽  
Large Diameter ◽  
Buckling Load ◽  
Bottom Plate ◽  
Element Analysis ◽  
Oil Storage ◽  
Bending Load ◽  
Stiffness Method ◽  
Shell Finite Element

The 2003 Tokachi-Oki earthquake caused severe damage to oil storage tanks due to liquid sloshing. Seven single-deck floating roofs had experienced sinking failures in large diameter tanks at a refinery in Tomakomai, Japan. The pontoons of the floating roofs might be buckled due to bending load during the sloshing. The content in the tank was spilled on the floating roof from small failures which were caused in the welding joints of pontoon bottom plate by the buckling. Then the floating roof began to lose buoyancy and sank into the content slowly. The elastic buckling of the pontoon is important from the viewpoint of the single-deck floating roof sinking. The authors had reported the buckling strength of the pontoons subjected to bending and compressive loads in the published literatures. The axisymmetric shell finite element method for linear elastic bifurcation buckling was used in the analysis. The buckling characteristics of the pontoon both with and without ring stiffeners were investigated. The initial geometrical imperfection may diminish the buckling load. This paper presents the lower bound buckling load according to the reduced stiffness method proposed by Croll and Yamada. The lower bound buckling loads of the pontoon subjected to circumferential bending load are evaluated from the axisymmetric finite element analysis which includes the reduced stiffness method.

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