For reliability-based design of pipe bends and elbows, a probabilistic characterization of the primary stress indices (B1 and B2) is essential. This paper aims at the characterization of the fabrication/geometric uncertainty in B2, for thin stainless steel long radius pipe bends, subjected to in-plane opening moment. This characterization is performed in a framework based on Monte Carlo simulation and nonlinear finite element analysis. A revision of the code-based expression for B2 is proposed where a random variable K replaces the constant numerator in this expression. The statistics for K are provided for different pipe nominal dimensions, which indicates that the existing provision gives a very conservative estimate of the plastic collapse moment for pipe bends subjected to in-plane opening flexure.

References

References
1.
Gupta
,
A.
, and
Choi
,
B.
,
2003
, “
Reliability-Based Load and Resistance Factor Design for Piping: An Exploratory Case Study
,”
Nucl. Eng. Des.
,
224
(
2
), pp.
161
178
.10.1016/S0029-5493(03)00133-X
2.
American Society of Mechanical Engineers
,
2004
,
Rules for Construction of Nuclear Facility Components
,
ASME Boiler and Pressure Vessel Code Committee, American Society of Mechanical Engineers
,
New York
.
3.
American Society of Mechanical Engineers
,
2007
,
Development of Reliability-Based Load and Resistance Factor Design (LRFD) Methods for Piping (CRTD-86)
,
ASME Boiler and Pressure Vessel Code Committee, American Society of Mechanical Engineers
,
New York
.
4.
Avrithi
,
K.
, and
Ayyub
,
B. M.
,
2009
, “
A Reliability-Based Approach for the Design of Nuclear Piping for Internal Pressure
,” Trans.
ASME J. Pressure Vessel Technol.
,
131
(
4
), p.
0412011
.10.1115/1.3122017
5.
Avrithi
,
K.
, and
Ayyub
,
B. M.
,
2009
, “
Strength Model Uncertainties of Burst, Yielding, and Excessive Bending of Piping
,” Trans.
ASME J. Pressure Vessel Technol.
,
131
(
3
), p.
0312071
.10.1115/1.3109983
6.
Avrithi
,
K.
, and
Ayyub
,
B. M.
,
2010
, “
Load and Resistance Factor Design (LRFD) of Nuclear Straight Pipes for Loads That Cause Primary Stress
,” Trans.
ASME J. Pressure Vessel Technol.
,
132
(
2
), p.
0211011
.10.1115/1.4000976
7.
Avrithi
,
K.
, and
Ayyub
,
B. M.
,
2010
, “
A Reliability-Based Approach for Low-Cycle Fatigue Design of Class 2 and 3 Nuclear Piping
,” Trans.
ASME J. Pressure Vessel Technol.
,
132
(
5
), p.
0512021
.10.1115/1.4001269
8.
Avrithi
,
K.
, and
Ayyub
,
B. M.
,
2010
, “
A Reliability-Based Expression of ASME B&PV Code Equation (11) for Class 2 and 3 Nuclear Pipes
,” Trans.
ASME J. Pressure Vessel Technol.
,
132
(
5
), p.
0545021
10.1115/1.4002460.
9.
Roy
,
P.
, and
Ghosh
,
S.
,
2012
, “
Statistical Characterisation of B2 for Nuclear Pipe Bends: In-Plane Closing Moment
,”
Nucl. Eng. Des.
,
249
, pp.
268
274
.10.1016/j.nucengdes.2012.04.018
10.
Ghosh
,
S.
, and
Roy
,
P.
,
2012
, “
Quantification of the Uncertainty in Stress Index B2 for Pipe Bends Subjected to Out-of-Plane Bending
,”
Int. J. Pressure Vessels Piping
,
95
, pp.
24
30
.10.1016/j.ijpvp.2012.05.003
11.
Chattopadhyay
,
J.
,
2002
, “
The Effect of Internal Pressure on In-Plane Collapse Moment of Elbows
,”
Nucl. Eng. Des.
,
212
(
1–3
), pp.
133
144
.10.1016/S0029-5493(01)00468-X
12.
Digiteo
,
2009
,
scilab User's Manual, version 5.1, The Scilab Consortium (Digiteo)
,
Le Chesnay Cedex
,
France
.
13.
Matzen
,
V. C.
, and
Yu
,
L.
,
1998
, “
Elbow Stress Indices Using Finite Element Analysis
,”
Nucl. Eng. Des.
,
181
(
1–3
), pp.
257
265
.10.1016/S0029-5493(97)00352-X
14.
Shalaby
,
M. A.
, and
Younan
,
M. Y. A.
,
1998
, “
Nonlinear Analysis and Plastic Deformation of Pipe Elbows Subjected to In-Plane Bending
,”
Int. J. Pressure Vessels Piping
,
75
(
8
), pp.
603
611
.10.1016/S0308-0161(98)00059-3
15.
Shalaby
,
M. A.
, and
Younan
,
M. Y. A.
,
1999
, “
Limit Loads for Pipe Elbows Subjected to In-Plane Opening Moments and Internal Pressure
,”
Trans. ASME J. Pressure Vessel Technol.
,
121
(
1
), pp.
17
23
.10.1115/1.2883661
16.
Simulia
,
2008
,
abaqus FEA User’s Manual, version 6.8, Dassault Systèmes
,
Vélizy-Villacoublay
,
France
.
17.
Tan
,
Y.
,
Wilkins
,
K.
, and
Matzen
,
V.
,
2002
, “
Correlation of Test and FEA Results for Elbows Subjected to Out-of-Plane Loading
,”
Nucl. Eng. Des.
,
217
(
3
), pp.
213
224
.10.1016/S0029-5493(02)00132-2
18.
Mourad
,
H. M.
,
1999
, “
Elastic-Plastic Behavior and Limit Load Analysis of Pipe Bends Under Out-of-Plane Moment Loading and Internal Pressure
,”
M.S. thesis
,
School of Sciences and Engineering Department, The American University in Cairo
,
Egypt
.
You do not currently have access to this content.