Effect of bend angle on plastic loads of pipe bends under internal pressure and in-plane bending

2007 ◽  
Vol 49 (12) ◽  
pp. 1413-1424 ◽  
Author(s):  
Yun-Jae Kim ◽  
Kuk-Hee Lee ◽  
Chang-Sik Oh ◽  
Bong Yoo ◽  
Chi-Yong Park
Keyword(s):  
Internal Pressure ◽  
Bend Angle ◽  
Plane Bending

Evaluation of collapse moment of pressurized 30°–180° bend pipes subjected to out-of-plane bending moment

2021 ◽  
pp. 095440622110614
Author(s):  
Manish Kumar ◽  
Pronab Roy ◽  
Kallol Khan
Keyword(s):  
Finite Element ◽  
Internal Pressure ◽  
Plastic Material ◽  
Bending Moment ◽  
Bend Angle ◽  
Pipe Bend ◽  
Geometric Imperfection ◽  
Initial Geometric Imperfection ◽  
Out Of Plane ◽  
Plane Bending

The present paper determines collapse moments of pressurized 30°–180° pipe bends incorporated with initial geometric imperfection under out-of-plane bending moment. Extensive finite element analyses are carried out considering material as well as geometric nonlinearity. The twice-elastic-slope method is used to determine collapse moment. The results show that initial imperfection produces significant change in collapse moment for unpressurized pipe bends and pipe bends applied to higher internal pressure. The application of internal pressure produces stiffening effect to pipe bends which increases collapse moment up to a certain limit and with further increase in pressure, collapse moment decreases. The bend angle effect on collapse moment reduces with the increase in internal pressure and bend radius. Based on finite element results, collapse moment equations are formed as a function of the pipe bend geometry parameters, initial geometric imperfection, bend angle, and internal pressure for elastic-perfectly plastic material models.

Effect of Bend Angle on Gross Plastic Deformation of Pipe Bends for Out-of-Plane Bending: A Study Using Plastic Work Curvature Method

2016 ◽  
Author(s):  
Anindya Bhattacharya ◽  
Sachin Bapat ◽  
Hardik Patel ◽  
Shailan Patel ◽  
Michael P. Cross
Keyword(s):  
Plastic Deformation ◽  
Internal Pressure ◽  
Bending Moment ◽  
Plastic Work ◽  
Bend Angle ◽  
Piping System ◽  
Plastic Collapse ◽  
Pipe Bend ◽  
Out Of Plane ◽  
Plane Bending

Bends are an integral part of a piping system. Because of the ability to ovalize and warp they offer more flexibility when compared to straight pipes. Piping Code ASME B31.3 [1] provides flexibility factors and stress intensification factors for pipe bends. Like any other piping component, one of the failure mechanisms of a pipe bend is gross plastic deformation. In this paper, plastic collapse load of pipe bends have been analyzed for various bend parameters (bend parameter = tRbrm2) under internal pressure and out-of-plane bending moment for various bend angles using both small and large deformation theories. FE code ABAQUS version 6.9EF-1 has been used for the analyses. The goal of the paper is to develop an expression for plastic collapse moment for a bend using plastic work curvature method when the bend is subjected to out-of-plane bending moment and internal pressure as a function of bend angle and bend parameter.

Effect of Bend Angle on Plastic Loads of Pipe Bends Under Internal Pressure and In-Plane Bending

2007 ◽  
Vol 31 (3) ◽  
pp. 322-330
Author(s):  
Kuk-Hee Lee ◽  
Chang-Sik Oh ◽  
Bong Yoo ◽  
Chi-Yong Park ◽  
Yun-Jae Kim
Keyword(s):  
Internal Pressure ◽  
Bend Angle ◽  
Plane Bending

scholarly journals Effect of Ovality in Inlet Pigtail Pipe Bends Under Combined Internal Pressure and In-Plane Bending for Ni-Fe-Cr B407 Material

2017 ◽  
Vol 62 (3) ◽  
pp. 1881-1887
Author(s):  
P. Ramaswami ◽  
P. Senthil Velmurugan ◽  
R. Rajasekar
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Internal Pressure ◽  
Limit Load ◽  
Outer Radius ◽  
Factor H ◽  
Geometrical Shape ◽  
Element Analysis ◽  
Pipe Bend ◽  
Plane Bending

Abstract The present paper makes an attempt to depict the effect of ovality in the inlet pigtail pipe bend of a reformer under combined internal pressure and in-plane bending. Finite element analysis (FEA) and experiments have been used. An incoloy Ni-Fe-Cr B407 alloy material was considered for study and assumed to be elastic-perfectly plastic in behavior. The design of pipe bend is based on ASME B31.3 standard and during manufacturing process, it is challenging to avoid thickening on the inner radius and thinning on the outer radius of pipe bend. This geometrical shape imperfection is known as ovality and its effect needs investigation which is considered for the study. The finite element analysis (ANSYS-workbench) results showed that ovality affects the load carrying capacity of the pipe bend and it was varying with bend factor (h). By data fitting of finite element results, an empirical formula for the limit load of inlet pigtail pipe bend with ovality has been proposed, which is validated by experiments.

Investigation of Smooth Pipe Bends Under the Effect of In-Plane Bending

2017 ◽  
Author(s):  
Diana Abdulhameed ◽  
Michael Martens ◽  
J. J. Roger Cheng ◽  
Samer Adeeb
Keyword(s):  
High Stress ◽  
Circular Cross Section ◽  
Bending Moment ◽  
Bend Angle ◽  
Bending Moments ◽  
Bend Radius ◽  
Pipe Bend ◽  
Cross Sectional ◽  
Smooth Pipe ◽  
Plane Bending

Pipe bends are frequently used to change the direction in pipeline systems and they are considered one of the critical components as well. Bending moments acting on the pipe bends result from the surrounding environment, such as thermal expansions, soil deformations, and external loads. As a result of these bending moments, the initially circular cross-section of the pipe bend deforms into an oval shape. This consequently changes the pipe bend’s flexibility leading to higher stresses compared to straight pipes. Past studies considered the case of a closing in-plane bending moment on 90-degree pipe bends and proposed factors that account for the increased flexibility and high-stress levels. These factors are currently presented in the design codes and known as the flexibility and stress intensification factors (SIF). This paper covers the behaviour of an initially circular cross-sectional smooth pipe bend of uniform thickness subjected to in-plane opening/closing bending moment. ABAQUS FEA software is used in this study to model pipe bends with different nominal pipe sizes, bend angles, and various bend radius to cross-sectional pipe radius ratios. A comparison between the CSA-Z662 code and the FEA results is conducted to investigate the applicability of the currently used SIF factor presented in the design code for different loading cases. The study showed that the in-plane bending moment direction acting on the pipe has a significant effect on the stress distribution and the flexibility of the pipe bend. The variation of bend angle and bend radius showed that it affects the maximum stress drastically and should be considered as a parameter in the flexibility and SIF factors. Moreover, the CSA results are found to be un-conservative in some cases depending on the bend angle and direction of the applied bending moment.

Failure of GRP Pipe Bends Under Out-of-Plane Flexure with and Without Pressure

1993 ◽  
Vol 207 (2) ◽  
pp. 133-141
Author(s):  
R Kitching ◽  
P Myler
Keyword(s):  
Internal Pressure ◽  
Polyester Resin ◽  
Design Procedure ◽  
Out Of Plane ◽  
Failure Loads ◽  
Smooth Pipe ◽  
Plane Bending ◽  
Chopped Strand Mat ◽  
Plane Flexure

Tests to failure have been carried out on six smooth pipe bends constructed by hand lay-up from polyester resin and glass in the form of chopped strand mat. The failure loads under out-of-plane bending only are compared with those where this type of loading is combined with internal pressure. The results are discussed in relation to the design procedure adopted in BS 7159: 1989.

The Assessment of Locally Thinned Areas Subject to a Hoop Stress and an Axial Stress: Background to the Guidance Given in Annex G of BS 7910:2013

2019 ◽  
Author(s):  
Andrew Cosham ◽  
Robert Andrews
Keyword(s):  
Internal Pressure ◽  
Axial Force ◽  
Hoop Stress ◽  
Axial Stress ◽  
Bending Moment ◽  
Full Scale ◽  
Plane Bending

Abstract Annex G Assessment of locally thinned areas (LTAs) in BS 7910:2013 is applicable to LTAs in cylinder, a bend and a sphere or vessel end. It can be used to assess the longitudinally-orientated LTA in a cylinder subject to a hoop stress and a circumferentially-orientated LTA in a cylinder subject to an axial stress (due to axial force, in-plane bending moment and internal pressure), and also to assess an LTA subject to a hoop stress and an axial stress. An outline of the origins of Annex G is given. A comparison with full-scale burst tests of pipes or vessels containing LTAs subject to a hoop stress and an axial stress is presented. It is demonstrated that the method in G.4.3 Hoop stress and axial stress is conservative.

Stress and flexibility factors for multi-mitred pipe bends subjected to internal pressure combined with external loadings

1972 ◽  
Vol 7 (2) ◽  
pp. 97-108 ◽  
Author(s):  
M P Bond ◽  
R Kitching
Keyword(s):  
Internal Pressure ◽  
Large Diameter ◽  
Pipe Bend ◽  
Bending Tests ◽  
Bending Load ◽  
Out Of Plane ◽  
Thin Walled ◽  
Plane Bending ◽  
Internal Pressures ◽  
Stress Patterns

The stress analysis of a multi-mitred pipe bend when subjected to an internal pressure and a simultaneous in-plane or out-of-plane bending load has been developed. Stress patterns and flexibility factors calculated by this analysis are compared with experimental results from a large-diameter, thin-walled, three-weld, 90° multi-mitred bend which was subjected to in-plane bending tests at various internal pressures.

Plastic Collapse Assessment Procedure in P-M Diagram Method for Pipe Bends With a Local Thin Area Under Combined Pressure and Out-of-Plane Bending Moment

2012 ◽  
Author(s):  
Kenji Oyamada ◽  
Shinji Konosu ◽  
Takashi Ohno
Keyword(s):  
Internal Pressure ◽  
Pressure Ratio ◽  
Bending Moment ◽  
Piping System ◽  
Assessment Procedure ◽  
Plastic Collapse ◽  
Diagram Method ◽  
Out Of Plane ◽  
Plane Bending ◽  
Collapse Assessment

Pipe bends are common elements in piping system such as power or process piping, and local thinning are typically occurred on pipe bends due to erosion or corrosion. Therefore, it is important to establish the plastic collapse condition for pipe bends having a local thin area (LTA) under combined internal pressure and external bending moment. In this paper, a simplified plastic collapse assessment procedure in p-M (internal pressure ratio and external bending moment ratio) diagram method for pipe bends with a local thin area simultaneously subjected to internal pressure, p, and external out-of-plane bending moment, M, due to earthquake, etc., is proposed, which is derived from the reference stress. In this paper, only cases of that an LTA is located in the crown of pipe bends are considered. The plastic collapse loads derived from the p-M diagram method are compared with the results of both experiments and FEA for pipe bends of the same size with various configurations of an LTA.

Theory of thin elastic shells applied to pipe bends subjected to bending and internal pressure

1972 ◽  
Vol 7 (4) ◽  
pp. 285-293 ◽  
Author(s):  
J A Blomfield ◽  
C E Turner
Keyword(s):  
Internal Pressure ◽  
Shell Theory ◽  
Coupling Effect ◽  
Governing Equations ◽  
Elastic Shells ◽  
Out Of Plane ◽  
Plane Bending

A consistent set of equations for the in-plane and out-of-plane bending of pipe bends is derived from the equations of shell theory with a correction for the coupling effect of internal pressure. The resulting governing equations are solved numerically and compared with other experimental and theoretical solutions.

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