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ssraja
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Join Date: Mar 2009
Posts: 10

shell to nozzle junction

11/25/2009 9:13 AM

hi all,

The elastic analysis (FEA) is showing high stress at shell to nozzle junction where it is welded. Since this stress is very high compare to allowable stress(1.5sm), whether it can be avoided or has to considered.

thanks
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varunpassi
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India - Member - Mechanical Engineer Engineering Fields - Petroleum Engineering - Mechanical Engineer

Join Date: Jun 2009
Location: Chennai (India)
Posts: 92
Good Answers: 2
#1

Re: shell to nozzle junction

11/25/2009 10:46 AM

this can not be avoided as these factors play a very critical role in the thickness of the shell. Generally based on the stress values the shell is designed with the minimum required shell plate thickness.

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Tornado
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Technical Fields - Technical Writing - New Member Engineering Fields - Piping Design Engineering - New Member

Join Date: May 2009
Location: Richland, WA, USA
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#2

Re: shell to nozzle junction

11/25/2009 11:31 AM

It appears that the vessel needs a reinforcement pad at the joint of nozzle to shell. I no longer have a copy, but the ASME Boiler and Pressure Vessel Code specifies the calculation for such pads.

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Abdel Halim Galala
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Engineering Fields - Piping Design Engineering - New Member Egypt - Member - Member since 02/18/2007

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#3

Re: shell to nozzle junction

11/26/2009 1:25 AM

Minimizing the stresses at nozzle-to-shell can be accomplished by one or more of the following:

a. Increasing the thickness of the nozzle.

b. Increasing the thickness of the shell at this area.

c. Adding additional reinforcing element like a pad.

d. Adding additional inward weld for protrude nozzle neck inside the vessel.

See the following nozzle reinforcement calculations as per ASME code, Section VIII, Division 1: Nozzle_Reinforcing_Calculation.

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dcongvt
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Join Date: Feb 2008
Posts: 47
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#4

Re: shell to nozzle junction

11/30/2009 2:44 AM

Or problem is caused by welding procedure, find another suitable procedure or use stress relief method for welding zone.

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