Nozzle Design- Codeware-Compress FAQs

7/24/2019 Nozzle Design- Codeware-Compress FAQs

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Knowledge Base Answers

Q:Why are nozzles not allowed to be exempt if they are located in Category A weld

joint?

UW-14(a) permits any opening that meets the reinforcing requirements of UG-37 or UG-39 to

be locate in a !ele "oint# $onsequently% small no&&les locate in a !ele "oint cannot be

e'empt from reinforcing area per UG-3(c)(3)(a)#

t is $oe!are* unerstaning that if a no&&le is locate on a category + "oint than the area

reinforcement requirements must be satisfie#

f a no&&le is locate on a !ele "oint an failing the area replacement metho than the

esigner may !ant to perform the analysis using the rules from +ppeni' 1-1,# o acti.ate this

go to the first screen of the no&&le ialog an clic/ on 0$alculation ptions0# his button !ill be

locate in the bottom left han corner of the ialog# Within this ialog chec/ the option 0Use

+ppeni' 1-1, in lieu of UG-370#

Q:C!"#$%% reports the form&la 'tr ( ")K*)+o , -.)%)$ / 012)"3' for 'tr' in the 456

78 calc&lation1 9ow is it deeloped?

his formula is applicable !hen the no&&le an its reinforcing area is locate totally !ithin the

0ishe0 portion of the hea% as efine in UG-37(a) for efinition of 0tr0% subparagraph (c) for

opening in an ellipsoial hea# 2or this case% the opening an reinforcement are locate entirely

!ithin a circle of , of the hea iameter# he require hea thic/ness 0tr0 for purposes of

area replacement is then base on that for a sphere of raius 516% !here 51 is gi.en by able

UG-37% an is the shell iameter (iameter of the hea)#

When the hea has a specifie outsie iameter% $8:;


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Q:9ow to model a soc;et welding co&pling in C!"#$%%1

$8:; 8oel 2ull $ouplings as a type 3 no&&le F n the figure belo!% the coupling is

moele as a type 3 no&&le using the imensions mar/e in re#

;'ample => 8oel Calf $ouplings as a type 1 no&&le F n the figure belo!% the half coupling

is moele as a type 1 no&&le using the imensions mar/e in re#

Page 2of 9 Nozzle Design Questions


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Q:What is A%!$ Appendix *6*0? Why does C!"#$%% apply +iision . r&les for

nozzle design to my +iision * essel?

2or 0large openings0 analy&e per +

erform stress analysis using +ppeni' 1-1, stress analysis metho (!hich is more

comprehensi.e than the stress analysis of +ppeni' 1-7(b))# Hote that the stress analysis

metho of +ppeni' 1-1, is use in lieu of the area compensation principles of UG-37 an

+ppeni' 1-7(a)#

Hote that both +ppeni' 1-7 an +ppeni' 1-1, ha.e limitations on the range of si&es an types

of construction to !hich they may be applie# f a no&&le falls outsie of these restrictions then

$8:;

;it the no&&le an clic/ the 0$alculation ptions0 buttonJ then select the esire metho on the

ialog>



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+ppeni' 1-7 has a number of limitations on the applicable geometry# $8:;


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Q:9ow does C!"#$%% determine the maxim&m allowable wor;ing press&re

-!AW"3 and maxim&m allowable press&re -!A"3 for nozzles?

1# he no&&le !all require thic/ness(trnin UG-37 cannot e'cee the no&&le thic/ness)

=# he .essel !all require thic/ness (trin UG-37 cannot e'cee the shell thic/ness)

3# he reinforcing area require cannot e'cee the reinforcing area a.ailable

4# UG-4I minimum no&&le !all thic/ness

I# UG-41(b)(1) !el strength calculations

# UW-1 minimum !el si&e requirements

7# 2or large openings% the rules of +ppeni' 1-7 are applie (or% alternati.ely% either +ppeni'

1-9 or 1-1,)

#


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Q:What happens when a nozzles reinforcement extends beyond the parent

component and onto adjacent components?

t is a problem !hen the $oe limits of reinforcement e'ten beyon the no&&leMs parent

component an onto a"acent components# n such a case the e'cess thic/ness a.ailable in the

a"acent component% to be utili&e as reinforcing area% may not be at least equal to that

a.ailable in the parent component% in !hich case the no&&le !ill be uner-reinforce in that

plane# etermining the thic/ness a.ailable in a"acent components is beyon !hat

$8:;


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$ngineering ss&es:

uring the course of .aliating $oe!areMs no&&le esign proposal to the i. = re-!rite

committee% !e ran se.eral hunre 2;+ moels to try an get a better unerstaning of the

beha.ior of no&&les in an aroun the forme hea /nuc/le region# t turns out that the $oe

area replacement rule assumptions onMt !or/ .ery !ell for no&&les in the /nuc/le region of

forme heas#

2;+ sho!s that for many high At ratios that meet the e'isting $oe rules the K stress

present in the /nuc/le region of the hea is consierably higher than the 1#I< allo!e by the

$oe# ;'cept in e'treme cases this is usually o#/# because in practice the hea eflects a little

an ta/es on a better shape (geometric strengthening)#

Generally% 2;+ sho!s that as the no&&le is mo.e from the center of the hea into the

/nuc/le region the stresses increase as e'pecte# n contrast% UG-37 area requirements stay

the same until you reach the , raius at !hich point they suenly increase to a higher

le.el !here they stay (e.en as you mo.e the no&&le further from the hea center)#

+ccoring to 2;+% the result of aing a no&&le in the /nuc/le region is not al!ays the

same# here are cases !here aing a no&&le in the /nuc/le region actually reuces the

stress in the hea# belie.e this may be ue to the nature of the compressi.e buc/ling present

in the /nuc/leJ the no&&le tens to act li/e a local 0stiffener0 for thinner heas# $ontrast this to

UG-37% !here aing a no&&le is assume to al!ays increase the stress in the hea#

+ccoring to 2;+% not all methos of pro.iing aitional reinforcement are equi.alent#

hic/ening a no&&le in the /nuc/le region may lea to an increase in stress in the hea

instea of the e'pecte ecrease# ne possible e'planation may be the no&&le as a local

0stiffener0 metaphor# f the no&&le gets too 0stiff0 it restrains the /nuc/le region% causing ahigher local bening# UG-37 assumes that aing e'tra material in the no&&le is "ust as goo

as aing a pa# f 2;+ is correct% then this is not the caseJ there are situations !here aing

a pa is the HKO !ay to correct the problem#

Q:Why does C!"#$%% determine nozzle weld sizes per 4W6* &sing corroded

thic;nesses?

$8:;


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How does COMPRESS determine the

chord opening for offset nozzles incylinders?

COMPRESS determines the chord opening for offset nozzles in cylinders using the method

described in ASME Section VIII, i!ision ", Appendi# $% see &igure $'()()") &ollo*ing

this method, COMPRESS uses the chord on the r+dius of the mid'pl+ne of the cylinder

reuired thic-ness in the corroded conditions)

.ote th+t the cylinder design pressure is used *hen determining the reuired thic-ness of

the cylinder) If the nozzle/s design mode is 0esign P, &ind MA1P 2 MAP0, then this

results in + slightly l+rger chord th+n if the nozzle/s MA1P *+s used3 +t MA1P thereuired thic-ness *ould be gre+ter +nd the chord *ill be sm+ller) 4he use of the reuired

thic-ness +t design pressure is thus slightly conser!+ti!e)

.umeric+l E#+mple3

cylinder I

5 67 int pressure

5 "87

cylinder th-5 ")69: +llo*+ble stress

5 "8877

cylinder corrosion

5 7)"9 E

5 "

corroded IR

5 cyl I ; 9 < corr

5 67 ; 9 < 7)"9

5 =7)"9

t red

5 P > IR ; ?S > E ' 7)6 > P@

5 "87 > =7)"9 ; ?"8877 > " ' 7)6 > "87@

5 7)977B

r+dius to mid'pl+ne of red th-, Rm

5 cyl I ; 9 < corr < red th- ; 9

5 67 ; 9 < 7)"9 < 7)9 ; 9

5 =7)96:79B6



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nozzle O

5 9B nozzle corrosion

5 7)"9

nozzle th-5 7)69: nozzle offset

5 "B

nozzle IR

5 nozzle O ; 9 ' nozzle th- < nozzle corr

5 9B ; 9 ' 7)69: < 7)"9

5 "")B:

+lph+ "

5 +rc cos??offset < nozl IR@ ; Rm@ 5 +rc cos??"B < "")B:@ ; =7)96:@@5 =9)676B(=

+lph+ 9

5 +rc cos??offset ' nozl IR@ ; Rm@

5 +rc cos??"B ' "")B:@ ; =7)96:@@

5 8:)9:996:

delt+

5 +lph+ 9 ' +lph+ "

5 8:)9:9= ' =9)676:

5 :9)6B:8

chord

5 9 > Rm > srt?" ' cos 9 ?delt+ ; 9@

5 9 > =7)96: > srt?" ' ?cos?:9)6B:8 ; 9@@ 9@

5 96)8B78


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Nozzle Design- Codeware-Compress FAQs