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  • PVElite Nozzle Input Query

    Discussion in 'The main mechanical design forum' started by pskpio, Jan 4, 2012.

    1. pskpio

      pskpio New Member

      Jan 2012
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      Hi Guys , I would like to understand a below query in PVElite Software .There is an option in Nozzle input dialaogue box says ID or OD Basis . If we consider the nozzle from Pipes then there is no much difference between both options.But For Integral / Hub & WN nozzles , Major difference in Area A6 .

      OD Basis - Area A6 is higher than ID Basis. I dont understand what is the difference between those and dono where to use it . Can anyone explain it please?

    3. D. Naukam

      D. Naukam Member

      Jul 2011
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      The input option is there to use pipe or other materials such as forgings or a rolled & welded plate cylinder. With pipe, the OD is held constant for a particular pipe size and the thickness and ID vary by pipe schedule. This would be when you want to use the OD basis. When using a forged neck, you are normally holding the ID constant to match a nominal pipe size or other connection; the OD and thickness are varied. The ID basis would be a proper selection here.
      So why the difference in area? The main reason is the required area will change. When selecting pipe, PVElite knows what the area removed is and will hold it the same for ID or OD basis options. When using actual for the thickness instead of nominal, you change the size of the opening you are trying to reinforce. Secondly, the required thickness of the nozzle will change. If you add the material to the ID, the ID gets smaller, less wall thickness required, more area available for reinforcement. Additionally, when calculating from the OD, the program uses equations in ASME BPV Code Sev VIII Appendix 1-1 instead of UG-27.

      Hope this explanation helped.


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