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Research Papers: Design and Analysis

Effect of Load Angle on Limit Load of Polyethylene Miter Pipe Bends 1

[+] Author and Article Information
Tarek M. A. A. EL-Bagory

Assistant Professor in Mechanical
Engineering Department
College of Engineering,
Majmaah University, KSA,
Majmaah, Riyadh 11952, Saudi Arabia
e-mail: telbagory@yahoo.com

Maher Y. A. Younan

Associate Dean
School of Sciences and Engineering,
The American University in Cairo AUC,
Cairo 11835, Egypt
e-mail: myounan@aucegypt.edu

Hossam E. M. Sallam

Professor in Civil Engineering Department
Faculty of Engineering,
Jazan University, KSA,
Jazan 82822-6694, Saudi Arabia
e-mail: hem_sallam@yahoo.com

Lotfi A. Abdel-Latif

Professor in Mechanical Design Department
Faculty of Engineering, El-Mataria,
Helwan University,
Cairo, El-Mataria 11724, Egypt
e-mail: lotlatif2012@gmail.com

Pipes & Plastic Products Company (PPP) in the 10th of Ramadan City-Egypt

1Participated in the Proceedings of the ASME 2010 Pressure Vessels & Piping Division/K-PVP Conference PVP2010 July 18–22, 2010, Bellevue, Washington, Paper Number: PVP2010-25491.

2Participated in the Euro-Mediterranean Innovation Marketplace 26th-28th January, 2010, Cairo-Egypt, “Ranked as the 1st among all the applicants of the contest” For the Invention “Testing Station for Natural Gas Piping Systems.”

3Sabbatical leave from Helwan University, Mechanical Design Department, Faculty of Engineering, El-Mataria, Helwan University, Cairo, El-Mataria 11724, Egypt.

4Sabbatical leave from Zagazig University, Materials Engineering Department, Faculty of Engineering, Zagazig University, Zagazig 44519, Egypt.

Contributed by the Pressure Vessel and Piping Division of ASME for publication in the JOURNAL OF PRESSURE VESSEL TECHNOLOGY. Manuscript received September 6, 2012; final manuscript received May 13, 2013; published online February 19, 2014. Assoc. Editor: Pierre Mertiny.

J. Pressure Vessel Technol 136(3), 031202 (Feb 19, 2014) (10 pages) Paper No: PVT-12-1142; doi: 10.1115/1.4026069 History: Received September 06, 2012; Revised May 13, 2013

The aim of this paper is to investigate the effect of crack depth a/W = 0–0.4 and load angle (30 deg, 45 deg, and 60 deg) on the limit load of miter pipe bends (MPB) under out-of-plane bending moment with a crosshead speed 500 mm/min. The geometry of cracked and un-cracked multi miter pipe bends are: bend angle, α = 90 deg, pipe bend factor, h = 0.844, standard dimension ratio, SDR = 11, and three junctions, m = 3. The material of the investigated pipe is a high-density polyethylene (HDPE), which is applied in natural gas piping systems. Butt-fusion welding is used to produce the welds in the miter pipe bends. An artificial crack is produced by a special cracking device. The crack is located at the crown side of the miter pipe bend, such that the crack is collinear with the direction of the applied load. The crack depth ratio, a/W = 0, 0.1, 0.2, 0.3, and 0.4 for out-of-plane bending moment “i.e., loading angle ϕ = 0 deg”. For each out-of-plane bending moment and all closing and opening load angles the limit load is obtained by the tangent intersection method (TI) from the load deflection curves produced by the specially designed and constructed testing machine at the laboratory (Mechanical Design Department, Faculty of Engineering, Mataria, Helwan University, Cairo/Egypt). For each out-of-plane bending moment case, the experimental results reveals that increasing crack depth leads to a decrease in the stiffness and limit load of MPB. In case of combined load (out-of-plane and in-plane opening; mode) higher load angles lead to an increase in the limit load. The highest limit load value appears at a loading angle equal, ϕ = 60 deg. In case of combined load (out-of-plane and in-plane closing; mode) the limit load decreases upon increasing the load angle. On the other hand, higher limit load values appear at a specific loading angle equal ϕ = 30 deg. For combined load opening case; higher values of limit load are obtained. Contrarily, lower values are obtained in the closing case.

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Figures

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Fig. 1

Schematic illustration of (a) miter pipe bend with attached straight pipe, (b) coordinates of load sign

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Fig. 2

Schematic illustration of loading mode and combined loading (−Fy +Fz, +FyFz)

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Fig. 3

Photographic picture of test rig

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Fig. 4

Load-deflection curves for out of plane bending (+Fz) at a/W = 0

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Fig. 5

Load-deflection curves for out of plane bending (+Fz) at a/W = 0.1

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Fig. 6

Load-deflection curves at load line (δ0) for out of plane loading (+Fz) at different crack depth

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Fig. 7

Trend of variation in collapse load with crack width ratio, a/W for out-of-plane loading (−Fz)

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Fig. 8

Load-deflection curves for combined load (−Fy +Fz) at loading angle 30 deg

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Fig. 9

Load-deflection curves for combined load bending (−Fy +Fz) at loading angle 45 deg

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Fig. 10

Load-deflection curves for combined load bending (−Fy +Fz) at loading angle 60 deg

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Fig. 11

Load-deflection curves at the load line (δ0) for combined load close (−Fy +Fz) at different loading angle

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Fig. 12

Variation of collapse load with loading angle for combined loading (−Fy +Fz)

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Fig. 13

Load-deflection curves for combined load open (−Fy +Fz) at loading angle 30 deg

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Fig. 14

Load-deflection curves for combined load open (+FyFz) at loading angle 45 deg

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Fig. 15

Load-deflection curves for combined load open (+FyFz) at loading angle 60 deg

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Fig. 16

Load-deflection curves at the load line (δ0) for combined load open (+FyFz) at different loading angle

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Fig. 17

Variation of collapse load with loading angle for combined loading (+FyFz)

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Fig. 18

Load-deflection curves at the load line (δ0) for combined loading close (−Fy +Fz) at different loading angle

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Fig. 19

Load-deflection curves at the load line (δ0) for combined loading open (Fy − Fz) at different loading angle

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Fig. 20

Variation of collapse load with loading angle for combined loading open and close

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