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RE: Stresses at Shell Attachments

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WRC 107 addresses spherical shells with rectangular attachments.  This
analysis is rather involved for temporary (and sometimes non code) loads.
Bednar does have a good procedure for cylinders that can be used for

I have used the simple method by Blodget for lifting lugs a number of times.
See "Design of Welded Structures",Blodget, section 6.6.3 'Effect of hanger
or support welded to shell'.

Ron Hill

HILL Consulting Engineering
Birmingham, Alabama  USA

-----Original Message-----
From: P.Rajendran [mailto:rajendra(--nospam--at)]
Sent: Saturday, February 20, 1999 7:17 AM
To: seaint
Subject: Stresses at Shell Attachments

Analysis of stresses at attachment to a spherical or cylindrical tank is
generally based on formulas, charts and graphs found in Welding Research
Council bulletin WRC 107,  WRC-297 and Pressure Vessel Design by
Bednar.  Attachment comprise either a nozzle or a clip (with or without
reinforcing pad).  My question is specific to the clip design.  I am not
asking for recommendation for commercial software.

In general, the above mentioned references have relatively more
information on clips attached to cylindrical vessels. For example,
rectangular reinforcing pad can be designed for a cylindrical vessel but
not for a spherical vessel.  So, question no. 1 is: how should a
rectangular pad be treated for a spherical vessel?

In actual practice, I have seen many vessels with bare clips, i.e.,
without  reinforcing pads. The books referred to in para 1. do not
provide any guidance to analyze stresses around a bare clip.  Therefore,
question no. 2 is: Are there any formulas and charts available to handle
such scenarios?  Designs of this kind have existed even before the
advent of computers.  How was the design performed then?

Rajendran, P.E.