Large Diameter Repad 1

[murk3]

Can anyone provide me with some guidance for designing repads for large diameter nozzles? Bednar indicates that nozzles 24" and larger with external loads may need intermediate welds to prevent buckling.

I have a vessel with a 48" diamter nozzle with loads that can be handled through the use of 20" wide repad. (Based on WRC107 analysis.) Should I be considering intermediate welds, stacked repads, gussets, etc. How would I go about proving these designs.

 

[SnTMan]

murk3, my guess is that FEA is the only way to verify such a design.

It can be more practical to use a heavy shell course rather than very large or thick pads.

Regards,

Mike

 

[LSThill]

Team Members

Review WRC-497 Large Diameter Ratio Shell Intersections

http://www.forengineers.org/cgi-bin/wrcbulletin/bulletin.pl

W. J. Koves, K. Mokhtarian, G.E.O. Widera E. C. Rodabaugh

WRC Bulletin 497

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Large Diameter Ratio Shell Intersections
Part 1: Design of Large Diameter Shell Intersections Subject to Pressure and External Loadings
Part 2: Parametric Finite Element Analysis of Large Diameter Shell Intersections (Internal Pressure)
Part 3: Parametric Finite Element Analysis of Large Diameter Shell Intersections (External Loadings)

Cylindrical shell intersections are structural configurations commonly used in many industries, such as pipeline transportation, nuclear and power engineering, chemical and petrochemical engineering, aerospace, etc. Under internal pressure or external loadings, high local stresses occur at the Shell intersection region due to the geometric discontinuity. Therefore, the study of the influence of the geometric parameters for a specific design configuration on the maximum stresses at shell intersections due to various loadings thus has great practical value.

In the past thirty years, considerable effort has been expended by stress analysts and designers all over the world in attempts to achieve a reasonable design procedure for shell intersections. WRC Bulletin 107 [1], which is based on Prof. P.P. Bijlaard's work, and WRC Bulletin 297 [2], which is based on Prof. Steele's work, provide guidance for the evaluation of shell and nozzle stresses due to external loadings. However, for large diameter ratio (0.5
A comprehensive parametric study of large diameter ratio cylindrical shell intersections subjected to internal pressure and external loadings was conducted on behalf of the Pressure Vessel Research Council. The configuration employed in this parametric study is idealized and consists of two thin shell cylinders intersecting normally with no transitions, reinforcements, or fillets in the junction region. This parametric study was divided into two phases. Phase I is for internal pressure while phase II is for external loadings. The external loadings considered are in-plane moment on the nozzle, out-of-plane moment on the nozzle, and axial force on the nozzle.

ISSN: 0043-2326
ISBN: 1-58145- 504-6
Library of Congress Catalog Card Number: 85-647116
Number of Pages: 55



Last Update: Thu, 8/25/2005 10:09:46 PM