Session: DA-02-01 Design & Analysis of Piping and Components - 1

Paper Number: 106810

106810 - A Review of Stress Intensification Factors for Reducers 

Determining an accurate stress intensification factor (SIF) is important for piping stress analysis. This paper reviews the history of SIF guidelines for reducers and the significance of reducer geometry on the calculated B31J SIF value.  

 

ASME B31.3 Appendix D, which specifies a SIF of 1 for reducers, was removed in the 2020 version of B31.3 and now references ASME B31J. This means all the process piping stress qualified with SIF=1 for reducers, may now have stress non-compliance with the new SIF of a value up to 2, resulting in layout or/and material changes in piping systems. This paper reviews the history of the development of SIF for reducers and the effect of this code update on default SIF values for reducers.  

  

Next, the significance of different reducer geometry parameters is investigated. In the initial stages of design, details such as exact reducer geometry are often not available. Initial analysis will therefore use default SIF values. These default SIF values should be conservative. If an area is a problem for stress, more detailed information can be used to refine the analysis. This paper compares SIF values calculated using default B31J values for reducer alpha, r2, and L2 values with SIF values calculated using realistic actual dimensions for alpha, r2 and L2. This comparison can be used to evaluate how conservative the default B31J values are. 

  

Additionally, the effect of different geometric parameters on the calculated B31J SIF value is evaluated. Although some of these parameters such as the L2 distance are not controlled by the ASME B16.9 reducer standard, they can have a significant effect on the SIF. It is suggested which geometry parameter(s) may be beneficial to specify in B16.9 to keep reducer SIF values more predictable. 

Presenting Author: Bhaskar Shitolé Wood

Presenting Author Biography: Bhaskar Shitolé is a mechanical engineer with 30 years of experience in the global EPC industry. He is a professional engineer registered in the province of Alberta. He has worked as a Piping and Mechanical engineer on Oil and Gas upstream, midstream, and downstream projects, as well as Mining and Power projects. He is a member of the ASME PVP CTBJ committee and the ASME codes and standards committee on ASME B31.3, NM-1 and PSD. He currently works as the Senior Piping and Mechanical Lead engineer for Wood PLC, Calgary, Alberta.

Authors:

Bhaskar Shitolé Wood
Cynthia Heinrichs Wood