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Finite Element Analysis

of Pressure Vessel and

Nozzle Junction

Revision: 0

Date: 29 March 2013

Author: Dharmit Thakore

2013

MOONI! EN"# P"$# %"& '

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Executive Summary"*e main o+,ecti-e of t*is .ro,ect /as to understand t*e Finite Element Analysis ca.a+ility of O.en

ource oft/are alome for Pre.rocessin( and Post.rocessin( and odeAster for analysis of a

Pressure Vessel Nozzle ,unction# Main (oal /as to calculate tresses +y *and and com.are t*em

/it* t*e Finite Element Analysis results#

Analysis /as carried out on a uarter section of a .ressure -essel /it* nozzle in t*e middle of t*e

(eometry4 /it* sufficient symmetry and ot*er +oundary conditions added for sta+ility of t*e model#%inear analysis usin( "etra*edral elements /as carried out for t*is study#

alome -ersion 5#3#0 and Aster -ersion 1#10#0 /as used for t*is analysis#

From t*e study it can +e seen t*at *and calculations closely matc* t*e Finite Element Analysis

results# Furt*er studies are reuired to e-aluate stresses and analyse t*em +ased on AME ection

VIII &i-ision 2#

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Table of ContentsE6ecuti-e ummary ################################################################################################################################# 1

Introduction ############################################################################################################################################ 3

Model 7eometry ##################################################################################################################################### 8

%oads and 9estraints ############################################################################################################################### :

Mes* ####################################################################################################################################################### 5Analysis of results ################################################################################################################################### )

!oo. tresses ###################################################################################################################################### )

%on(itudinal tresses ########################################################################################################################## ;

Internal Pressure ############################################################################################################################### 11

Only Force ######################################################################################################################################### 13

Force and Internal Pressure om+ined %oadin( ############################################################################### 1:

onclusions ########################################################################################################################################### 1)

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Introduction

"*e main (oal of t*is study /as to -alidate Finite Element Analysis .erformed for follo/in( cases

1# Internal Pressure /it* !oo. stress only

2# Internal Pressure /it* %on(itudinal stresses only

3# Internal Pressure /it* +ot* !oo. and %on(itudinal stress

8# Force of ;000N in direction (oin( left to ri(*t if facin( t*e nozzle

:#

All of t*e a+o-e four cases com+ined

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Model Geometry"*e model (eometry is a uarter section

of a Pressure Vessel modelled in .ositi-e

>$? zone of t*e coordinate system# "*is

.ressure -essel *as a nozzle at t*e centre

of it .ointin( in .ositi-e >$ direction#

"*e (eometry modellin( is carried out in

alome 7eometry module4 mes*in( /as

carried out in alome Mes* module and

t*en t*e mes* /as e6.orted in #ms*

format# Finite Element Analysis /as

carried out in odeAster and t*e result

/as e6.orted in anot*er #ms* format#

"*is result mes* /as im.orted in alome

a(ain and Post Processin( /as carried out

/*ere &is.lacements and Vonmises

stresses /ere e-aluated#

=uarter model of t*e entire .ressure

-essel /as used in t*is study as t*e not

modelled section of t*e .ressure -essel

/as -ery remote to t*e Nozzle (eometry#

Flan(e /as not modelled on t*e nozzle end to minimise mes* size and com.utation time as t*is is

t*e standard .ractice used in commercial soft/are .ac@a(es#

olid modellin( /as carried out in t*is study# om.ara+le results can +e o+tained +y usin( s*ell

elements4 and in future anot*er study may +e carried out to understand t*e difference +et/een t*e

t/o modellin( a..roac*es#

O& of Pressure Vessel *ell 3000mm I& of Pressure Vessel *ell 2;B0mm

O& of Nozzle 300mm I& of Nozzle 2B0mm

!ei(*t of t*e Pressure Vessel *ell 3000mm !ei(*t of t*e Nozzle 200mm

Figure 1: Model Geometr

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Loads and RestraintsVertical faces are (i-en symmetric +oundary

condition# Vertical Face in t*e >O? .lane

(ets +oundary condition of &$0# Vertical

Face in t*e $O? .lane (ets +oundarycondition of &>0# !orizontal +ottom face

(ets +oundary condition of &>04 &$0 and

&?0

Fi-e %oad cases /ere considered for t*is

study# "o +alance t*e un+alanced .ressure

an eui-alent force is a..lied on t*e front

face of t*e nozzle#

%oads to +e considered for t*is study are

Internal Pressure 0#: MPa

Force ;000 N

Modulus of Elasticity CED 210 7Pa

As t*e nozzle is facin( .ositi-e >$ direction4

force on t*e nozzle face /as reduced in > and

$ direction and t*en a..lied to t*e face# o

t*e force of ;000N in lateral direction of t*e nozzle s*ell ,unction is reduced to 5353N in $ directionand 5353N in > direction#

&>4 &$4 &? 0

&>0

&$0

Figure 2: Restraints

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Mesh3& tetra*edron mes* /as used for t*is study#

"etra*edron ma6imum -olume /as restricted to

ma6imum :0 in alome#

7lo+al (eometry /as mes*ed /it* t*e a+o-e

confi(uration usin( automes*# Automatic tetra*edron

!y.ot*esis /as used for (lo+al (eometry# "*e ed(es of

t*e nozzle Cinside and outsideD at +ot* ends /ere (i-en a

u+mes* /it* euidistance di-ision of 100#

"*e linear mes* *as BB)12 tetra*edron elements#

At t*is sta(e4 linear mes* is used /it* automatic mes*in(

for t*e (lo+al mes* /it* 100 linear elements on t*e nozzle

ed(es /ere modelled as u+mes* to ma@e t*e ed(es fine

and *a-e more finite elements for +etter results around

t*e nozzle s*ell ,unction#

Figure 3: Mesh !n"ormation

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Analysis of results

Hoop Stresses

For t*e first load case4 stresses /ere o+tained for internal .ressure on t*e s*ell and nozzle ,unction

/it* force modelled on t*e nozzle face for +alancin( un+alanced .ressure# "*e dis.lacement and

VonMises .lot are s*o/n +elo/ in Fi(ures 8 and : res.ecti-ely#

Figure #: $oo% &tress ' Dis%lacement

*an(e in &iameter for t*is Pressure Vessel is calculated as follo/s

*an(e in &iameter

(2 ) .

(2 0.3) 0#B;Bmm

FE analysis a+o-e in Fi(ure 8 s*o/s dis.lacement in $ello/ colour *i(*li(*t as 0#5mm# One of t*e

ma,or reason to contri+ute to t*e lo/er dis.lacement com.ared to manual calculation is t*at t*e

+oundary conditions are -ery close to eac* ot*er and t*e .resence of Nozzle in t*e centre of t*e

model#

!oo. stress for t*is Pressure Vessel is calculated as follo/s

!oo. tress

.

):MPa

As can +e seen in Fi(ure : +elo/4 t*e VonMises stresses for t*e ma,ority of t*e s*ell a/ay from

+oundaries and Nozzle is at an a-era(e of ): MPa

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Figure (: $oo% &tress ' )onMises

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Longitudinal Stresses

For t*e second load case4 stresses /ere o+tained for force actin( on t*e to. face of t*e s*ell to

simulate %on(itudinal tresses# "*e dis.lacement and VonMises .lot are s*o/n +elo/ in Fi(ures 5

and ) res.ecti-ely#

Figure *: +ongitudinal &tress , Dis%lacement

%on(itudinal stress for t*is Pressure Vessel is calculated as follo/s

%on(itudinal tress

.

3)#:MPa

As can +e seen in Fi(ure ) +elo/4 t*e VonMises stresses for t*e ma,ority of t*e s*ell a/ay from

+oundaries and Nozzle is at an a-era(e of 3) to 80 MPa

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Figure -: +ongitudinal &tress ' )onMises

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Internal Pressure

For t*e t*ird load case4 stresses /ere o+tained for +ot* Internal Pressure actin( on t*e internal face

of t*e Pressure Vessel and Nozzle to simulate !oo. stress and Force actin( on t*e to. face of t*e

s*ell to simulate %on(itudinal tresses# "*e dis.lacement and VonMises .lot are s*o/n +elo/ in

Fi(ures B and ; res.ecti-ely

Figure .: !nternal /ressure ' Dis%lacement

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Figure 9: !nternal /ressure , )onMises

om+ined stress for t*is Pressure Vessel is calculated as follo/s

om+ined tress ( !"#$"%& ) (' 3'.) 58#;:MPa

As can +e seen in Fi(ure ; a+o-e4 t*e VonMises stresses for t*e ma,ority of t*e s*ell a/ay from+oundaries and Nozzle is at an a-era(e of 5: MPa

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Only Force

For t*e fourt* load case4 stresses /ere o+tained for %ateral force actin( on t*e nozzle face# "*e

dis.lacement and VonMises .lot are s*o/n +elo/ in Fi(ures 10 and 11 res.ecti-ely

Figure 10: Force nl ' Dis%lacement

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Figure 11: Force nl , )onMises

ome close u. screen s*ots of nozzles*ell interface are s*o/n +elo/# First screens*ot is for t*e

VonMises stress on t*e outside surface of t*e nozzle s*ell ,unction#

Figure 12: Forcenl loseu% o" utside sur"ace

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econd screens*ot +elo/ is for t*e VonMises stress on t*e Inside surface of t*e Nozzle s*ell

,unction#

Figure 13: Forcenl loseu% o" !nside sur"ace

Force and Internal Pressure Combined Loading

For t*e fift* load case4 stresses /ere o+tained for %ateral force actin( on t*e nozzle face and Internal

Pressure actin( on t*e inside face of t*e s*ell and nozzle# "*e dis.lacement and VonMises .lot are

s*o/n +elo/ in Fi(ures 18 and 1: res.ecti-ely

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Figure 1#: Force and !nternal /ressure omined ' Dis%lacement

Figure 1(: Force and !nternal /ressure omined , )onMises

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ConclusionsFrom t*is study it can +e concluded t*at Finite Element analysis results matc* t*at of *and

calculations# "*is study is not e6*austi-e and /as conducted to try doin( Finite Element analysis of a

Pressure Vessel Nozzle section usin( alome for modellin( and .ost.rocessin( and odeAster for

analysis

"*is study is ,ust a .reliminary analysis# For furt*er study follo/in( actions are recommended

1# Gse of !e6a*edral elements

2# Gse of 2ndorder or !i(*er order elements

3# Mes* refinement around t*e nozzle s*ell ,unction

8# !a-e minimum : elements in t*e t*ic@ness of t*e s*ell and nozzle

:# E-aluate tresses +ased on AME ection VIII &i-ision 2 Part : rules#

5# Gse lar(er surface of t*e s*ell so t*at t*e distance +et/een t*e nozzle and +oundary

conditions is more t*an /*at is used in t*is study#