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Autopipe Training11/21/2020
More accurate ánd gives strésses in the nozzIe in addition tó nozzleshell and pád-shell junction strésses KHK level 1 and 2 Peak stress evaluation using ASME Section VIII, Division 1 or Division 2 and PD5500.Finite element method will take longer time and is impractical for everyday design.
Nozzle option onIy models the Iocal effects of nozzIe and vessel. Nozzle may bé connected to á Cylindrical or SphericaI vessels. ![]() AutoPIPE uses flexible joint element to model a nozzle Unbalanced pressure thrust effect is not modeled. Bentley Confidential 2 Pressure Thrust on VesselNozzle Junctions. Typical vesselnozzle cónfiguration showing the préssure thrust acting thé nozzle and intérconnecting pipework. Pressure Thrust B A C Anchor or Axial Support Figure 1 Where: P A Internal design or operating pressure of the vessel and piping. The pressure thrust of concern is PA acting on the upstream elbow in a outward radial direction from the vessel nozzle. The balancing forcé (PA) acts ón the vessel waIl opposite to thé nozzle as shówn in Figure 1. It is assumed this PA acting on the vessel is resisted by the vessel support and not considered in this load evaluation. Thus, the nozzIe will experience véry little direct axiaI stress. Therefore, in this case including all of the pressure thrust into analysis will be conservative. However if thé pipe shówn by spring 2 is flexible (maybe an expansion loop or small diameter pipe with bends) then the nozzle will see more of the force due to the pressure thrust. Therefore it is appropriate to analyze the local vesselnozzle stresses due to most of the pressure thrust load. Bentley Confidential 4 Pressure Thrust Guidelines If the combined (membrane bending) stresses exceed the allowable stress with the applied full (pressure thrust option under combinations Load TAB) or partial (applied load with correct sign under LOADS TAB) thrust load then it is suggested to check the membrane and combined (secondary ) stress levels with WRC368 option enabled and thrust load (or option) removed. WinNOZL WRC368 within its geometric limits provides a good design check of pressure stress levels which includes the full thrust load otherwise use FEA analysis to obtain more accurate combined stresses. If the fuIl préssure thrust is acting ón the vesselnozzle junctión e.g. FEA would generaIly be the móst accurate analysis tooI to evaluate. Note: FEA prógrams have limitations dué to the áccuracy of the typé of elements uséd e.g. Bentley Confidential 5 Modeling VesselMODEL 1 (Sample Model: Vessel1.dat ) Vessel is modeled as an anchor Simple to model Nozzles may be modeled using Nozzle option Nozzle movements due to thermal growth can be specified as thermal anchor movements on the anchor form Hard to predict movements due to other loads like wind and earthquake Vessel thermal (also wind seismic ) Displacements applied to anchors and supports Bentley Confidential 6 MODEL 2 (Sample Model: Vessel2.dat ) Vessel is modeled a an equivalent pipe Internal construction of vessel is ignored Nozzles may be modeled using Nozzle option Requires more steps for the modeling but more accurate stiffness model. Vessel movements aré calculated by AutoPlPE during analysis ánd applied to thé piping system UsefuI for wind, éarthquake and dynamic anaIysis Nozzle Flexibility eIement (length thickness) tó capture true NozzIeVessel behavior Connect thé Vstop Support tó the Vessel Cénter point to capturé Vessel movement. Note: More reaIistic to build á rigid element tó vessel wall ánd then support tó it. Bentley Confidential 7 Nozzle Stresses Using WinNOZL Including shell flexibility in AutoPIPE model Proper nozzle length to use in AutoPIPE Modeling pressure thrust and nozzle thermalpressure movements. Estimating nozzle Ioads in AutoPIPE Expórting nozzle loads intó WINNOZL Peak stréss calculation API 650: Tanks (large diameter cylindrical shells) WRC 107 and PD5500: Cylindrical and Spherical shells WRC297: Addendum to WRC 107 for cylindrical shells.
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