Pipe Stress Analysis Research Articles

Residual Stress Distribution in Austenitic Stainless Steel Pipe Butt-Welded Joint Measured by Neutron Diffraction Technique

This paper describes residual stress measurements and analysis of austenitic stainless steel pipe with a butt-welded joint. The measurements were done with neutron diffraction and strain gauge techniques. The measured results had typical characteristics of butt-welded pipe regarding both the decline of stress along the axial direction and the bending distribution of axial stress along the radial direction. The measured residual stress distribution by neutron diffraction was shifted more to the tensile side than that by the finite element method simulation. However, the measured radial and axial strains, except for the hoop strain determined by neutron diffraction, coincided well with analysis strains. The hoop strain was actually equivalent strain converted by a correction method because a different lattice plane had to be used to measure hoop strain. This might be one reason why the difference occurred. Therefore, future study of the correction method would be desirable.

Dynamic analysis of multi-layered filament-wound composite pipes subjected to cyclic internal pressure and cyclic temperature

Based on the three-dimensional anisotropic elasticity, the stress analysis of multi-layered filament-wound composite pipes subjected to cyclic internal pressure and temperature loading is conducted in this article. The time-dependent stress, strain and deformation distributions are numerically obtained by the use of the finite difference technique. The pressure and temperature are considered to be symmetrical about the axis of the cylinder and independent of the axial coordinate. Each layer of the pipes is made of a homogeneous, anisotropic and linearly elastic material and it is assumed that the material properties do not change with increasing the temperature. The shear extension coupling is also considered because of lay-up angles. Numerical results obtained from the present model are compared with other published results and good agreement has been achieved.

Long term hydrostatic resistance of multilayer pipes

This contribution deals with the short term and the long term behaviour of multilayer pipes subjected to internal hydrostatic pressure. A new methodology for prediction of long term behaviour of multilayer pipes under internal hydrostatic pressure taking into account the material differences and the composite pipe construction is presented, which considers the possibility of the composite polymeric pipe having a metallic interlayer. The three dimensional theory of thick walled multilayer pipes together with a combined quadratic/linear regression analysis is used, and the contribution of each component to the long term strength of the composite pipe is quantitatively assessed. This procedure is incorporated in the pipe software ADAP developed by the author that deals with automated design and analysis of pipelines. Short term stress analysis of multilayer pipe consisting of two polymeric facings and a metallic interlayer is carried out with three methods; namely the analytical method of multilayer thick walled tubes, the finite element method, and the computational software ADAP. In addition, an analytical stability analysis was carried out. It has been shown that all three methods produce similar quantitative and qualitative stress results. According to these computations, for multilayer polymers/metal/polymer pipes, higher stress values are predicted for the metallic interlayers. Using the new long term extrapolation procedure, the layer at which the failure under internal pressure would be initiated is identified and the state of stress of each layer is quantitatively assessed. Using this extrapolation methodology for multilayer polymer pipes at elevated temperatures, the theoretical sharp knee predicted by the existing standards is replaced by a transition zone between the ductile and the brittle behaviour of thermoplastic layers. An example of this procedure for a multilayer pipe consisting of two polymeric facings and a metallic interlayer is presented. The proposed methodology can be used as an extrapolative procedure for prediction of the long term resistance of composite and multilayer pipes as well as for optimisation of multilayer plastics and hybrid pipes.

Decision-making on pipe stress analysis enabled by knowledge-based systems

This paper presents engineering decision-making on pipe stress analysis through the application of knowledge-based systems (KBS). Stress analysis, as part of the design and analysis of process pipe...

Stress analysis of pipe bends subjected to internal fluid pressure using the finite element technique

Ovality and thinning are the commonly observed shape irregularities that are introduced during the forming process of pipe bends. Pipe bends with ovality and thinning are subjected to higher stresses than pipe bends with perfectly circular cross-sections. The stresses introduced in pipe bends with different ovality and thinning for a particular internal pressure are calculated using the finite element method. The constant allowable pressure ratio for different ovality and thinning is presented at different bend radii. The allowable pressure ratio increases, attains a maximum, and then decreases as the values of ovality and thinning are increased. A mathematical correlation to determine the allowable pressure in terms of bend ratio, pipe ratio, per cent thinning, and per cent ovality is presented.

Stress analysis of non-conventional composite pipes

In this study stress and failure analyses of polygonal-shaped composite pipes have been performed; five different shapes of circular, triangular, rectangular, pentagonal and hexagonal pipes are considered. The variation of peak hoop stress over different corner fillet radii, fiber orientation under internal pressure, and torsion loading have been investigated. Failure analysis methods utilized maximum principal stress and Tsai–Wu criteria.

New Piping Flexibility Rules in ASME B31.3, Appendix P

Alternative rules for performing flexibility analysis were added, as Appendix P, in ASME B31.3, the Process Piping Code, 2004 edition. These rules are considered to be more comprehensive than before; they were designed around computer flexibility analysis. To determine stress range, the difference in stress states, considering all loads, is computed. This paper describes the new rules, their intent, and provides several example piping stress analyses, comparing the results of an analysis using the Appendix P rules with that using the rules in the base Code.

Pipe-anchor discontinuity analysis utilizing power series solutions, Bessel functions, and Fourier series

One of the paradigmatic classes of problems that frequently arise in piping stress analysis discipline is the effect of local stresses created by supports and restraints attachments. Over the past 20 years, concerns have been identified by both regulatory agencies in the nuclear power industry and others in the process and chemicals industries concerning the effect of various stiff clamping arrangements on the expected life of the pipe and its various piping components. In many of the commonly utilized geometries and arrangements of pipe clamps, the elasticity problem becomes the axisymmetric stress and deformation determination in a hollow cylinder (pipe) subjected to the appropriate boundary conditions and respective loads per se. One of the geometries that serve as a pipe anchor is comprised of two pipe clamps that are bolted tightly to the pipe and affixed to a modified shoe-type arrangement. The shoe is employed for the purpose of providing an immovable base that can be easily attached either by bolting or welding to a structural steel pipe rack. Over the past 50 years, the computational tools available to the piping analyst have changed dramatically and thereby have caused the implementation of solutions to the basic problems of elasticity to change likewise. The need to obtain closed form elasticity solutions, however, has always been a driving force in engineering. The employment of symbolic calculus that is currently available through numerous software packages makes closed form solutions very economical. This paper briefly traces the solutions over the past 50 years to a variety of axisymmetric stress problems involving hollow circular cylinders employing a Fourier series representation. In the present example, a properly chosen Fourier series represent the mathematical simulation of the imposed axial displacements on the outside diametrical surface. A general solution technique is introduced for the axisymmetric discontinuity stresses resulting from an anchor restraint on a selected of pipe geometry. These solutions can be economically implemented on today's symbolic calculus software packages with no loss in solution accuracy when compared to often more expensive techniques such as the finite element method. Verification of the axisymmetric solution technique is illustrated by the comparison of results for the closed form solutions versus those approximated by the finite element technique. Extensions of the general axisymmetric solution technique to other geometries and applied loads are also discussed while the numerical and graphical results are tendered.

Advanced software for stress analysis of composite pipe systems

Conventional FEA is typically too time consuming and cumbersome for an entire GRP pipe system and a specialized pipe stress analysis package should be used. But not all pipe analysis packages handle GRP equally well, so before buying you should investigate the software's ability to handle composite materials with non-isotropic properties advises Alfred L. Newberry of FEMech Engineering.

907 凍結光弾性法及び有限要素法による内圧を受ける海老継ぎ管の応力解析

There are many pipes in nuclear-energy power stations and chemical plant. In there multi-mitred pipes are seen frequently. They need high safety. Accordingly this study aims at stress analysis of pressurized multi-mitred pipe using photoelastic stress freezing method and finite element method. There are many primary factors affecting the distribution of stress. The study aimed at stress analysis of influences of change in crossed axis angle, radius of fillet curvature ρ, thickness, multi-mitered pipe's length L, number of crossings.

Exact yield hyper-surface for thin pipes

A yield hyper-surface for pipe sections subjected to combinations of normal forces, internal and external pressure, twisting moments, biaxial bending moments and biaxial shearing forces is developed. The formulation is based on the fully plastic capacity of the pipe as determined by the maximum distorsional energy density yield criterion. The solution is obtained by maximizing a lower bound analysis and yields a yield hyper-surface that is exact within the limitations of the formulation. The developments are expressed as universal non-dimensional relationships suitable for limit states design of elevated pipes, submerged pipes, offshore platforms and structural tubular steel members. Previously established interaction relations for bending moments, axial forces and internal pressure are recovered as a special case of the general solution. The merits of using the yield hyper-surface to characterize generalized plastic hinge behavior in elasto-plastic pipe stress analysis are presented.

Discussion of “On the Evaluation of Dynamic Stresses in Pipelines Using Limited Vibration Measurements and FEA in the Frequency Domain” (Moussa, W. A., and Abdelhamid, A. N., 1999, ASME J. Pressure Vessel Technol., 121, Aug., pp. 241–245)

Discussion of “On the Evaluation of Dynamic Stresses in Pipelines Using Limited Vibration Measurements and FEA in the Frequency Domain” (Moussa, W. A., and Abdelhamid, A. N., 1999, ASME J. Pressure Vessel Technol., 121, Aug., pp. 241–245)

113 偏肉断面を有する曲がり管の面内曲げ解析(OS1-4 材料・構造体の変形解析)(OS1 材料の力学・疲労・破壊現象)

113 偏肉断面を有する曲がり管の面内曲げ解析(OS1-4 材料・構造体の変形解析)(OS1 材料の力学・疲労・破壊現象)

Running Force in Medium to High-Curvature Wellbores: An Experimental Study and Numerical Simulation of Laboratory and Field Cases

This paper presents a novel approach to measure and estimate running force for various laboratory and field conditions. The experimental and simulation procedures of different rod/pipe sizes running through various laboratory/field conditions are described in detail. Tests were conducted on rods to measure the running force for various laboratory cases obtained from dimensional analysis. The generated experimental results were used to calibrate a typical laboratory finite element model from which calibrated parameters are used to estimate the running force for prescribed field cases. Both the experimental and simulated field results revealed that the running force depends on the radius of curvature, hole clearance, horizontal section, and contact scenario significantly. Stress analysis of pipes running through curved and horizontal sections showed that pipes undergo elastic and plastic deformation, and the nature of deformation depends on the pipe size and radius of curvature.

Analysis of filament-wound sandwich pipe under internal pressure

Using the classical laminated plate theory, a computer model has been developed to investigate stresses and strains of thick-walled sandwich pipes under internal pressure. The sandwich pipe is created using non-reinforced material for the core layer and an alternate-ply material for the skin layers. Considering the complicated material properties of the skin layers reinforced by alternate-ply composites, the analysis is based on treating typical sandwich pipes that are three-dimensional, cylindrical, and orthotropic. The computer model conducts stress and strain analysis of sandwich pipe with different winding angles. The optimum winding angles have been found to be in the 60° range, and the strength of the sandwich pipe has been found to decrease rapidly when the core layer modulus is less than 20 GPa.

Failure Investigation of a Low Chrome Long-Seam Weld in a High-Temperature Refinery Piping System

Abstract The results of an investigation of a long-seam welded low chrome pipe that failed in a high-temperature refinery piping system are presented in this paper. Based upon the results of a metallurgical investigation, which included a creep testing program and a detailed finite element stress analysis, the cause of the failure has been attributed to creep damage at the weld seam. The metallurgical investigation and creep testing program indicated that the 1-1/4 Cr-1/2 Mo pipe material was normalized and exhibited greater than average creep strength and creep ductility. The results of a piping stress analysis indicated that all pressure, weight, and thermal stresses were in compliance with the ASME B31.3 Piping Code (ASME, 1993a). Nonetheless, the pipe failed after only 100,000 h at a nominal hoop stress of 6 ksi (41.4 MPa) with an operating temperature range of 970°F (521°C) to 1000°F (538°C). Results from subsequent detailed finite element stress analyses of the failed pipe indicated that very high localized bending stresses were present in the pipe due to peaking at the long-seam weld. These stresses partially relax by creep, but after 100,000 h they were still approximately 38 percent higher than the nominal hoop stress. The creep strains resulting from stress relaxation and those associated with the long-term value of the sustained stresses cause severe creep damage at the weld seam. As a result of this damage, cracks initiated at the inside of the pipe and primarily grew through the HAZ/fusion line until an 18-in. through-wall crack developed. The pipe was produced to ASTM A691, Grade 1-1/4 Cr, Class 41 (ASTM, 1989), and the peaked geometry was found to satisfy the fabrication tolerances of this standard. The need for the development of an acceptable tolerance for peaking in addition to the outside diameter and out-of-roundness fabrication tolerances currently included in this standard is highlighted for long-seam welded pipe that is to operate in the creep range.

A database to evaluate stress intensity factors of elbows with throughwall flaws under combined internal pressure and bending moment

The advent of the leak-before-break (LBB) concept has widely replaced the traditional design basis event of a double-ended guillotine break (DEGB) in the design of primary heat transport (PHT) piping. The use of the LBB concept requires postulation of the largest credible cracks at highly stressed locations and demonstration of their stability under the maximum credible loading conditions. Stress analysis of PHT piping in nuclear power plants shows that the highly stressed piping components are normally elbows and branch tees. This necessitates detailed fracture mechanics evaluation of such piping connections by computing their stress intensity factors (SIF) and/or J-integral. Simple analytical solutions for evaluation of the SIF and J-integral for cracks in straight pipes are readily available in the literature. However the same type of solution for elbows and tees is limited in the open literature. In the present work a database is generated to evaluate the SIF for throughwall circumferential and longitudinal cracks under combined internal pressure and bending moment. Different parameters used to characterise a cracked elbow are pipe factor ( h), pipe bore radius to thickness ratio ( r t ) and crack length. Another parameter (ϱ) is used to consider the relative magnitude of stresses due to internal pressure and remote bending moment. This database has been used to derive closed-form expressions to evaluate the SIF for elbows with cracks in terms of the aforementioned parameters.

LBB technology application to the primary piping system of the NPP V1 Jaslovske Bohunice

Due to several deficiences of the WWER Model 230 type reactor a leak before break demonstration of this reactor is of primary importance. The complex project for NPP V1 Jaslovske Bohunice includes a static and dynamic stress analysis of the primary piping, a fatique damage analysis, leak rate assessments and an analysis of the stability of the heavy components supports. The material database includes data on fracture mechanics, on assessment of corrosion properties, and on the influence of 100000 hr service exposure on base metal and welds including disimilar welds. The program was supported by large scale experiments on RPV safe-end, pressurizer safe-end, elbow welds with through-wall cracks and leak rate measurements. The results and applications are discussed.

A finite element model for predicting stresses and slip in flexible pipe armouring tendons

An eight degree-of-freedom curved beam element has been developed for the purpose of stress and slip analysis of flexible pipe armouring tendons. The fact that the tendon is forced to slide in the curvilinear plane of the supporting pipe structure is utilized to minimize the number of degrees of freedom. Differential geometry is further used in order to describe the loading and reference system of each tendon during subsequent deformation, thus avoiding a large part of congruence transformations. Numerical examples and comparison with measurements on a real flexible pipe specimen are presented. The test data and the numerical model show very good agreement.

Introduction to Pipe Stress Analysis

Pipe Stress Analysis. Design of Pressure Components. Pipe Span Calculation. ANSI Piping Codes and ASME Codes. Expansion Loops and Expansion Joints. Flanged Joints. Piping Connected to Nonrotating Equipment. Piping Connected to Rotating Equipment. Special Topics. Nuclear Components Code, ASME Section III. Appendixes. Index.