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6 32 1 25585Ladkrabang Engineering Journal, Vol. 32, No. 1, March 2015

-Flexibility Factors of Unreinforced Branch Pipe Connections Subjected to In-Plane and Out-of-Plane Bending Moments for Fixed-Simply End Conditions

(d/D, D/T, t/T) 0.333 ( d/D ( 1, 20 ( D/T ( 250 d/D ( t/T ( 3 - - : , , Abstract

Flexibility factors are an important parameter in pipe stress analysis, especially, for branch pipe connections subjected to external moments, in-plane and out-of-plane. Inaccuracy of these can influence to calculated moments which result in inaccurate displacement stress range. The purpose of this paper is to investigate the effects of lengths of the run and branch pipeson flexibility factors and correlation equations for these flexibility factors on geometry parameters (d/D, D/T, t/T) for range 0.333 ( d/D ( 1, 20 ( D/T ( 250 and d/D ( t/T ( 3 subjected to in-plane and out-of-plane bending moments for fixed-simply end conditions are proposed. Finite element method with linear elastic property is employed for stress and flexibility factor evaluation. At first, FEM stress results of run-branch pipe intersection are verified by comparing with the available experimental data, the study on effect of lengths for the run and branch pipes, the determination of flexibility factors and correlation equations for these flexibility factors was carried out, respectively. The simulated result, the stress distribution trend, shows good agreement with the experimental data. Moreover, the FEA simulations of varying lengths of the run and branch pipesand fixed-simply end conditions, were performed and the calculated results indicate that run and branch pipe lengths have an effect on flexibility factors.Key words: Flexibility factorBranch pipe connections, Run-branch pipe intersection1. (Branch connection or unreinforced fabricated) (Branch pipe connection) (Branch pipe) (Bending Moment) (Run pipe) (Flexibility factors) (Displacement stress range) ASME B31.3 319.3 [2] 1 ( D) (Rigid) WRC Bulletin 329 [3]

The ASME Boiler & Pressure Vessel Code, Section 3, NB-3687.5 [6] 2 D/T ( 100 d/D ( 0.5 WRC 297 [4] 59 60 - (Simply -Simply support) d/D ( 0.5 WRC 297 Fujimoto Soh [7] - (Fixed-Fixed support) 50 ( D/T 300, 0.5 ( d/D ( 0.95 0.25 ( t/T ( 0.95 Wais, Rodabaugh Carter [8] (1) - (Fixed-Free support) (2) - (Fixed-Fixed support) 7.50 ( D/T ( 99, 0.125 ( d/D ( 1.0 7.50 ( d/t ( 198 Xue, Widera Sang [1] 20 ( D/T ( 250, 0.333 ( d/D ( 1.0 d/D ( t/T ( 3 - (Fixed-Free support)

- (Fixed-Simply support) 1

(Benchmark study) 3 Solid

Widera [1] 1 d/D = t/T = 0.5, D/T = 99 D = 9.9 (ORNL-1 [13]) 1

2.

1 (Theory of Elasticity) WRC Bulletin 463 [5] (K) [12] 2

(1) E M [10] (1)

(2) , (2) ():

(3)

(4)

(5) A C 1

2 [5] ():

(6)

(7)

(8) B D 1 3.

3.1 (Benchmark Study)

ORNL-1 [13] ORNL-1 [13] 4 - (Fixed-Free support) (2400 -) (600 -)

(FEA) 3 Solid (20-node isoparmetric) (E) 30 x 106 (psi) 0.3

4 ORNL-1 [13] Mesh (Mesh) WRC Bulletin 493 [9] (decay distance region) (Circumferencial direction) 3.75 (Perpendicular direction) 2 (Maximum aspect ratio) 5 4 5

6 (FEA)

3.2 (Effect of the Lengths of the Run and Branch Pipes)

1 d/D = 0.333, 0.5, 0.75 1 D/T =100 t/T = d/D D = 100

(2) 2. 2 3.3 (Flexibility Factors)

43 1 3 (2) 3 3

3.4 (correlation equations)

R [11] 3 4 FEA

(9)

(10)

4 1 FEA Widera [1] 4.

- (d/D, D/T, t/T) d/D (9) (10) 6. [1] Widera, G. E. O., et al, Flexibility Factors for Branch Pipe Connections Subjected to In-Plane and Out-of-Plane Moments, Journal of Pressure Vessel Technology, Vol. 128, pp. 8994, 2006.[2]ASME Code for Pressure Piping, B31.3, Chemical Plant & Refinery Piping, 2012.

[3] Rodabaugh, E. C., Accuracy of Stress Intensity Factors for Branch Connections, WRC Bulletin 329, 1987.

[4] Mershon, J. L., et al, Local Stresses in Cylindrical Shells Due to External Loadings on Nozzles, WRC Bulletin 297, 1984.

[5] Rodabaugh, E. C., and Wais, E. A., Standard Flexibility Factor Method and Piping Burst and Cyclic Moment Tests for Induction Bends and 6061-T6 and SS 304 Transition Joints, Report 1, WRC Bulletin 463, 2001.[6] ASME Sec.3 Div. 1, Rules for Construction of Nuclear Power Plant Components, 2012.[7] Fujimoto, T., and Soh, T., Flexibility Factors and Stress Indices for Piping Components with D/T