This document discusses modeling pipe connections to pressure vessels in START-PROF pipe stress analysis software. It describes three options for modeling nozzle elements: 1) at the end node of a pipe, 2) connected to a rigid element between the pipe and vessel, and 3) inserted directly into the vessel shell element. Both local and global flexibility of the connection can be considered using options 2 and 3. The document also provides details on properties that can be specified for nozzle elements, including material, temperature, flexibility, and allowable loads/stresses.

1. ModelingPipingConnectiontoPressure Vessels
Readabout START-PROFpipe stressanalysissoftware
For NozzlesSTART-PROFautomaticallyconsiderfollowing:
 Nozzle movementdue totemperature expansion
 Nozzle Flexibility
 CheckNozzle Loadsor CheckStressesinNozzle-Shell Connection
Analysisresultscanbe foundin Loadson NozzlesandEquipmentTable.See also"How toReduce the Nozzle
Loads inSTART-PROF"
The flexibilityof junctionpointbetweenvessel andpipe consistsof twoparts:local flexibilityandglobal
flexibility.Local flexibilityconsiderlocal deformationof the shell nearthe nozzle.The global flexibilityconsider
bendingof the whole vessel like pipebending.
Nozzle elementisusedformodellingof pipe connectiontothe pressure vesselsandcolumns.There canbe
three options:
1. Nozzle elementatthe endnode.Inthiscase global flexibilityisnottakenintoaccount,exceptthe situation
when"FEM" optionisused.

2. 2. The vessel ismodeledusing cylindrical shell element(3).The lengthbetweennozzle andintersectionpoint
betweenpipeaxisandvesselaxisismodeledusing rigidelement(1).Nozzleelementshouldbe insertedinto
the pointbetweenpipeandrigidelement(2).Thismethodcanbe usedtomodel the equipmentof any
complexityandconnectionof anynumberof pipestoit.Both local and global flexibilitycan be considered
usingthismethod.

3. 3. The vessel ismodeledusing cylindrical shell element.Nozzleelementinsertedintoconnectionpoint
betweenpipeaxisandcylindricalshelllikeaordinarytee (node 1).Inthiscase START-PROFwill automatically

4. create the rigidelement,noneedtoadditmanually.Bothlocal andglobal flexibilitycanbe consideredusing
thismethod.
Properties

5. Prope
rty
Description
Name Textfield.Elementcanbe sortedbyname and selectedinthe projecttree
Mater
ial of
Vessel
Material frommaterialsdatabase
Manuf
acturi
ng
For ASME B31.1, ASME B31.3, DL/T 5366-2014 seamlesspipe will alwaysuse Wl=1.0.For electric-
weldedpipe Wl willbe specifiedfromdatabase. More...

6. techn
ology
of
Vessel
Whenusing GOST 32388-2013, pipe physical propertiesare takenfromdifferent materialsdatabases
dependingonpipe type (seamless/welded).
Temp
eratur
e of
Vessel
, Тop
Designtemperature in operatingmode.More...
Thispropertycan be changedin different operation modes.Tosee the value of thispropertyinall
operatingmodespushthe button
Remo
ve
restrai
nts for
hange
r
selecti
on
If this optionisactivated,thensome restraintsare removedfromnozzle elementduringweightrunof
springand constantefforthangerselection.Duringmainanalysisrestraintsare working.Thistrick
allowstoremove the weightpartof loadingfromthe nozzle element.Springswill take the exactload,at
whichdisplacementsfrompure weightloadiszero.Options:
 Remove vertical restraint.Onlyverticalrestraintwill be releasedduringhangerselection
 Remove customrestraints.Youshouldmanuallychoose whichrestraintsshouldbe released
duringhangerselection
 Remove all restraints.Duringhangerselectionall directionrestraintswillbe released
Intern
al
diame
ter of
vessel
Internal diameterof vessel
Lengt
h
from
ancho
r to
nozzle
X,Y,Z
Distance betweenanchorof the pressure vessel andnozzle.
These valuesare usedwhenmodellingnozzlemovementsdue totemperature expansionof the vessel.
Usedonlywhennozzle addedintothe endnode.Movementalongeachaxisiscalculatedusing
equationΔX=α(Tope-Tambient)LX.
Thermal expansionfactoristaken frommaterial database forselectedmaterial.

7. Nozzle
flexibil
ity
There are a several options:
 Rigid.Flexibilitiesare zero.Nozzleconsideredasrigid
 Manually.Six flexibilitiesshouldbe specifiedmanually
 By WRC 297
 By PD 5500
 By FEM. Flexibilitiesare automaticallycalculatedusingfiniteelementmethod(PASS/Nozzle-
FEM software).Thisoptionisunavailable atthismoment.Itisunderdevelopmentandbecome
available soon.
Lrad - Linearflexibilityalongnozzle axis
Lcir - Linearflexibilityperpendiculartonozzle axisandperpendiculartothe vessel axis
Llong- Linearflexibilityperpendiculartonozzle axisandalongthe vessel axis
Rrad - Angulartorsionflexibilityof nozzle(aroundnozzleaxis)
Rcir - Angularflexibilityinplane of nozzleandvessel axes
Rlong- Angularflexibilityout-of-plane of nozzle andvessel axes

9. Allow
able
loads
/
stress
es
There are a several options:
 No check.Loadson the nozzle are not checked
 Manually.Usershouldspecifysix allowable loadsmanually
 Stresscheckby WRC 107/537/297. START-PROFwill checkthe local stressesinthe shell
element(orheadelement) andlocal stressesinthe junctionpointbetweenvessel andnozzle
usingWRC 107/537/297
 Stresscheckby FEM. This optionisunavailableatthismoment.Itisunderdevelopmentand
become availablesoon.
 AllowableloadsbyFEM.This optionisunavailable atthismoment.Itisunderdevelopmentand
become availablesoon.