scholarly journals Author’s Response to “Letter to the Editor commenting on ‘Maximum Stresses and Flexibility Factors of Smooth Pipe Bends With Tangent Pipe Terminations Under In-Plane Bending’” (1984, ASME J. Pressure Vessel Technol., 106, pp. 219–220)

1984 ◽  
Vol 106 (4) ◽  
pp. 312-313
Author(s):  
G. Thomson
Keyword(s):  
Pressure Vessel ◽  
Letter To The Editor ◽  
Smooth Pipe ◽  
Plane Bending ◽  
Maximum Stresses

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.

Limit Load of Pressurized Cylinder-Nozzle Intersection Using Finite Element Method

2016 ◽  
Vol 853 ◽  
pp. 276-280
Author(s):  
Xiao Hui Chen ◽  
Shi Yuan Liu ◽  
Tao Hu ◽  
Dong Xue Pei
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Stress Concentration ◽  
Pressure Vessel ◽  
Branch Pipe ◽  
Bending Moment ◽  
Plastic Limit ◽  
Plane Bending ◽  
Outside Diameter ◽  
Element Method

Pressure vessel contained with different nozzles which caused geometric discontinuity of the pressure vessel wall, which resulted in stress concentration around the nozzle. There may be the chances of failure of vessel junction, which was attributed to the high stress concentration. Therefore, detail stress distribution analysis need to be done for pressure vessel with the nozzle. Determination of limit pressure at different location on lateral nozzle by using finite element method. Lateral nozzle was subjected to internal pressure and in-plane bending moment. Results found that plastic hinge occurred in the nozzle-vessel junction area shoulder. Plastic limit loading increased with the increasing of outside diameter and wall thickness of branch pipe when the size of primary piping was constant value, whereby the influence of outside diameter of branch pipe was more remarkable. Moreover, engineering estimation formulas of plastic limit in-plane bending moment was obtained based on plastic limit loading database.

Theoretical Analysis of the Stresses in Pipe Bends Subjected to Out-of-Plane Bending

1967 ◽  
Vol 9 (2) ◽  
pp. 115-123 ◽  
Author(s):  
R. T. Smith
Keyword(s):  
Theoretical Analysis ◽  
Digital Computer ◽  
Design Procedure ◽  
Theoretical Work ◽  
Theoretical Treatment ◽  
Bending Moments ◽  
Out Of Plane ◽  
Plane Bending ◽  
Comparison Of The Results ◽  
Maximum Stresses

Most of the experimental and theoretical work on the flexure of pipe bends has concerned bending in the plane of the bend but comparison of the results of some experiments using out-of-plane bending with calculations based on existing theories indicated a need for a more exact theoretical analysis of this form of loading. In this paper a comprehensive theoretical treatment of the elastic flexure of curved tubes already published for in-plane bending has been adapted to deal with out-of-plane bending. The equations for both forms of loading have been programmed for solution by a digital computer and a design procedure is suggested to find the maximum stresses due to combined in-plane, out-of-plane and torsional bending moments.

The Effect of Nozzle Spacing on the Pressure Stresses at the Intersection of Cylindrical Nozzles and Shells

1967 ◽  
Vol 89 (3) ◽  
pp. 360-368 ◽  
Author(s):  
R. M. Stone ◽  
S. Hochschild
Keyword(s):  
Pressure Vessel ◽  
Reactor Vessel ◽  
Stress Indices ◽  
Cylindrical Pressure Vessel ◽  
Maximum Stresses ◽  
Nozzle Spacing

This paper considers the effect of nozzle spacing on the pressure stresses at cylindrical pressure vessel shell and nozzle junctures. This consideration is based on a photoelastic test conducted to determine if the stress indices of Section III of the ASME Boiler and Pressure Vessel Code may be used in analysis of reactor vessel designs containing circumferential nozzle spacings smaller than presently allowed by the Code. The five circumferential spacings used in the test were 109 deg, 34 deg, 30.2 deg, 26.4 deg, and 22.5 deg. The stresses at the locations of interest are presented as a function of nozzle spacing. These results show that the maximum stresses for spacings below the Code minimum are smaller than those at the Code minimum.

Plastic Loads for Piping Branch Junctions Subjected to Combined Pressure and In-Plane Moment Loads

1994 ◽  
Vol 208 (1) ◽  
pp. 31-43 ◽  
Author(s):  
M G Kirkwood ◽  
D G Moffat
Keyword(s):  
Internal Pressure ◽  
Pressure Vessel ◽  
Experimental Results ◽  
Plastic Collapse ◽  
Design Code ◽  
Nominal Diameter ◽  
Plane Bending

Experimental results are presented from plastic collapse tests on a series of 150 mm nominal diameter piping branch junctions. The loads considered are internal pressure and both branch and run pipe in-plane bending. Plastic loads are defined and presented for individual loads followed by combined pressure and moment results in the form of plastic load interaction diagrams. The results are discussed in the light of the ASME III nuclear pressure vessel design code rules.

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