design procedure for pressure vessel

8/10/2019 Design Procedure for Pressure Vessel

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TABLE OF CONTENTS

S. NO TITLEPAGE NO

. INTRODUCTION TO PRESSURE VESSELS

4

1.1. BASIC TERMINOLOGIES USED 5

1.2 CYLINDERS AND SPHERS 19

2. ANALYTICAL DESIGN OF METHANATOR

26

2.1 GIVEN DATA 28

2.2 REQUIRED DIMENTIONS OF METHANATOR 29

2.3 METHANATOR AS A THIN CYLINDER 30

2.4 THIC NESS OF SHELL 32

2.5 THIC NESS OF 2!1 ELLIPSOIDAL HEAD 34

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2." OPENING IN THE PRESSURE VESSELS 35

2.# SELECTION OF FLANGES 3#

2.8 THIC NESS OF S IRT OR DESIGN OF SUPPORTS 39

2.9 LOADINGS 44

2.10 STRESSES IN RESPONSE TO DIFFERENT LOADS 45

a) INTERNAL PRESSURE

45b) WEIGHT

46

c) WIND LOAD

49

d) SEISMIC LOAD

54

2.11 COMBINATION OF STRESSES 5#

2.12 COMPARISION 58

2.13 DESIGN OF ANCHOR BOLTS 58

2.14 $ELDING OF PRESSURE VESSELS "2

3. ANALYSIS BY ANSYS

67

3.1 ANSYS "8

3.2 ANSYS INPUT METHODS "9

3.3 SHELL 51 #0

3.4 ANALYSIS OF METHANATOR UNDER INTERNAL PRESSURE USING

SHELL 51 #1

3.5 ANALYSIS OF METHANATOR TO COMMAND $INDO$ #2

3." ANALYSIS OF METHANATOR THROUGH GUI #2

3.# TO FIND THE HOOP AND LONGITUDINAL STRESS ON ANSYS 88

3.8 DISPLACEMENTS OF NODES 91

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4. COMARISION AND CONCLUSION

92

4.1 MEMBRENE STRESSE IN METHANATOR 934.2 COMARISION OF ANSYS AND ANALYTICAL SOLUTION 94

4.3 CONCLUSION 9"

REFERENCES%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

TABLES %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

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INTRODUCTION

TOPRESSUREVESSE

LS

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. BASIC TERIMINOLOGIES USED

VESSEL:

A container or structural envelope in which materials are processed,treated, or stored; for e ample, pressure vessel, reactor vessel, a!itatorvessel, and stora!e vessels "tan#s$%

&'ESS('E VESSEL:A metal container !enerall) c)lindrical or spheroid, capa*le or

withstandin! various loadin!s%

S+'A -:An) forced chan!e in the dimensions of a *od)% A stretch is a tensile

strain; a shortenin! is a compressive strain; an an!ular distortion is a shearstrain% +he word strain is commonl) used to connoteunit strain %

S+'ESS:nternal force e erted *) either of two ad.acent parts of a *od) upon

the other across an ima!ined plane of separation% /hen the forces are parallel to the plane, the stress is called shear stress ; when the forces arenormal to the plane the stress is callednormal stress ; when the normal stressis directed toward the part on which it acts is calledcompressive stress ;

when it is directed awa) from the part on which it acts it is calledtensile stress.

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S+'ESSES - &'ESS('E VESSEL: Lon!itudinal S1 stress% ircumferential "hoop$ S2 stress%

S1 and S2 called mem*rane "diaphra!m$ stressor vessel havin! a fi!ure of revolutionendin! stress

Shear stressiscontinuit) stress at an a*rupt chan!e in thic#ness or

Shape of the vessel

+E-S LE S+'E-5+6:+he ma imum stress a material su*.ected to a stretchin! load can

withstand without tearin!%

+E-S LE S+'ESS:Stress developed *) a material *earin! tensile load%

+ES+ &'ESS('E:+he re7uirements for determinin! the test pressure *ased on

calculations are out lined in (5899"c$ for the h)drostatic test and (581 "*$for the pneumatic test% +he *asis for calculated test pressure in either ofthese para!raphs is the hi!hest permissi*le internal pressure as determined

*) the desi!n formulas, for each element of the vessel usin! nominalthic#ness with corrosion allowances included and usin! the allowa*le stressvalues for the temperature of the test% " ode (A8 $


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+6E'


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/EL -5:+he metal .oinin! process in ma#in! welds%

n the construction of vessels the weldin! process is restricted *) the

code "(/82B$ as follows;1% Shielded metal arc, su*mer!ed arc, !as metal arc, !as tun!sten arc,

atomic h)dro!en metal arc, o ) fuel !as weldin!, electro8sla!, andelectron *eam%

2% &ressure weldin! process: flash, induction, resistance, pressure+hermit, and pressure !as%

C EL &? -+:+he lowest stress at which strain increases without increase in stress%

or some purpose it is important to distin!uish *etween the upper )ield point, which is the stress at which stress8stain curve first *ecome hori=ontaland the lower )ield point, which is the somewhat lower and almost constantstress under which the metal continues to deform% ?nl) a few materials

e hi*it a true )ield point; for some materials the term is sometimes used ass)non)mous with )ield stren!th%

S&E 5'AV +C:+he ratio of the densit) of a material to the densit) of some standard

material, such as water at a specified temperature, for e ample, 4D or D %

?r "for !ases$ air at standard conditions of pressure and temperature%


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S+A L +C ? VESSEL:"Elastic sta*ilit)$ +he stren!th of the vessel to resist *uc#lin! or

wrin#lin! due to a ial compressive stress% +he sta*ilit) of a vessel is

severel) affected *) out of roundness%

S6ELL:Structural element made to enclose some space%


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SE ?- A'C S+'ESS:A normal stress or a shear stress developed *) the constraint of

ad.acent parts or *) self8constraint of a structure% +he *asic characteristic ofa secondar) stress is that it is self8limitin!% Local )ieldin! and minordistortions can satisf) the conditions which cause the stress to occur andfailure from one application of the stress is not to *e e pected% E amples osecondar) stress are: !eneral thermal stress; *endin! stress at a !rossstructural discontinuit)%

&? SS?-SF'A+ ?:+he ratio of lateral unit strain to lon!itudinal unit strain, under the

conditions of uniform and unia ial lon!itudinal stress within the proportional limit%

&?S+/EL 6EA+ +'EA+


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&'ESS('E /EL -5:A !roup of weldin! processes wherein the weld is completed *) use

of pressure%

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-E(+'AL AG S:+he line of =ero fi*er stress in an) !iven section of a mem*er su*.ect

to *endin!; it is the line formed *) the intersection of the neutral surface and

the section%


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such as wood, it is necessar) to distin!uish moduli of elasticit) in differentdirections%


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J? -+ E E- C:

A numerical value e pressed as the ratio of the stren!th of a riveted,welded, or *ra=e .oint to the stren!th of the parent metal%

L?A -5:Loadin! "loads$ are the results of various forces% +he loadin!s to *e

considered in desi!nin! a vessel : internal or e ternal pressure, impact loads,wei!ht of the vessel, wind and earth7ua#e, superimposed loads, local load,effect of temperature !radients%" ode (5822$%

L?/8ALL?C S+EEL:A harden a*le car*on steel !enerall) containin! not more than a*out

1K car*on and one or more of the followin! components; "less than$ 2Kman!anese, 4Knic#el, 2Kchromium, % K mol)*denum, and

%2Kvanadium%

6EA+ +'EA+


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A +?' ? SA E+C:+he ratio of the load that would cause a failure of a mem*er or

structure, to the load that is imposed upon it in service%

A+ 5(E:+endenc) of materials to fracture under man) repetitions of a stress

considera*l) less than the ultimate static stren!th%

E E-+' +C:A load or component of a load normal to a !iven cross section of a

mem*er is eccentric with respect to that section if it does not act throu!hcentroid% +he perpendicular distance from the line of action of the load toeither of principle central a is is the eccentricit) with respect to that a is%

E E- C ? A /EL E J? -+:+he efficienc) of the welded .oint is e pressed as a numerical 7uantit)

and is used in the desi!n of a .oint as a multiplier of the appropriateallowa*le stress value% " ode (A8 $

ELAS+ :apa*le of sustainin! stress without permanent deformation; the term

is also used to denote conformit) to the law stress8strain proportionalit)% An

elastic stress or elastic strain is a stress or strain within the elastic limit%

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ELAS+ L < +:+he least stress that will cause permanent set%

ES 5- &'ESS('E:

+he pressure used in determinin! the minimum permissi*le thic#nessor ph)sical characteristics of the different parts of the vessel% " ode (58 $

ES 5- +E


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ALL?C:An) of a lar!e no% of su*stances havin! metallic properties consistin!

of two or more elements; with few e ceptions, the components are usuall)

metallic elements%

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.2 CYLINDERS AND SPHERES:

Vessels such as steam *oilers, air compressors, stora!e tan#s,accumulators and lar!e pipes are su*.ected to internal fluid pressure which isuniforml) distri*uted% All the a*ove mentioned vessels are classified asc)linders or spheres%

+6 - CL - E':

f the ratio of the thic#ness to the internal diameter i%e% tNd is less tha*out 1N2 , the c)linder is assumed to *e thin c)linder%

+6 > CL - E':f the ratio of thic#ness to the internal diameter i%e% tNd is !reater tha

1N2 , the c)linder is assumed to *e thic# c)linder%

S+'ESSES - CL - E'S:+he followin! stresses are illustrated in fi!% "1$ and fi!% "2$

' (< E'E-+ AL ?' 6??& S+'ESS:

+he stress which acts tan!ent to the circumference and perpendicularto the a is of the c)linder is called circumferential or hoop stress% t isdenoted *) f h%

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L?-5 +( -AL S+'ESS:

+he stress which acts normal to circumference and parallel to the a isof the c)linder is called lon!itudinal stress% t is denoted *) f l%

'A AL S+'ESS:+he stress which acts in a direction perpendicular to the internal

surface is called radial stress% t is denoted *) f r % 'adial stress is ver) smallas compared to f l and f h in case of thin c)linder and is therefore i!nored%

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A-ALCS S ? +6 - CL - E':onsider the e7uili*rium of half c)linder of len!th OLF sectioned

throu!h a diameteral plane as shown in fi!, "3$

Let the internal diameter *eOdF and the thic#ness OtF; OpF is the appliinternal pressure, fh the hoop stress and fl the lon!itudinal stress%

6??& S+'ESS:onsider the elemental rin! of the c)linder su*tendin! an an!le PQ%

Let ds H arc len!th of elemental rin! H r%orce actin! on elemental rin! H p Rarea

H prPQLVertical component of this force H prPQL SinQ+otal vertical force HprL1 SinQPQ

H 8prl "cos 1 T os $ H 2prL

H pdL e7%"1$ut

dL H hori=ontal pro.ected area%

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So+otal vertical force H pdL H intensit) of pressure R hori=ontal

pro.ected area%

+his force tries to *urst the c)linder into two halves and is calledO*urstin! forceF%

urstin! force H H pdLAnd

'esistin! force H stress R resistin! area H f h R 2tL

or e7uili*rium of c)linderurstin! force H 'esistin! force

pdL H f hR2tLf h H pdN2t e7%"A$

L?-5+( -AL S+'ESS:

ross sectional area HI N4 d2 +otal force at the end of c)linder H pR IN4 d2 +his force tries to *urst the c)linder at the ends of c)linder and is

called O*urstin! forceF%urstin! force H H pR IN4 d2

'esistin! force H stress R resistin! area

H f lR Idt for e7uili*rium of c)linder

urstin! force H resistin! force

&R IN4 d2H f lR Idt

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l H pdN4t e7% " $omparin! "A$ and " $

l H1N2 f h

+6 - S&6E' AL S6ELL:n case of spherical shell also, the radial stress will *e ne!lected and

the circumferential or hoop stress will *e assumed to *e constant%

As shown in the fi!% the two stresses are e7ual to due to s)mmetr)% i%f h H f l H f

ross8sectional area H I N4d2 urstin! force H pR I N4d2

'esistin! force H stress R resistin! areaH f R dt

or e7uili*rium of shellurstin! force H resistin! force

& R I N4d2H f R dtf H pdN4t

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CL - E' AL S6ELL / +6 6E< S&6E' AL E- S:As shown in the fi!% let t1 *e the thic#ness of the c)linder and t2 *e the

thic#ness of the hemisphere, the internal diameter *ein! assumed the same

for *oth%

S+'ESSES - +6E CL - E' AL &?'+ ?-:f the shell is su*.ected to an internal pressure p, stresses in the

c)linder will *e;6oop stress, f hH pdN2t1And

Lon!itudinal stress, f l HpdN4t16oop strain,Uh H f hNE T f lNE H 1NE "f h T f l$

H1NE "pdN2t1 8 pdN4t1$ H 1NE ""2pd 8 pdN4t1$$Uh H pdN4t1E "2 8 $

Lon!itudinal strain, Ul H f lNE 8 fhNE H pdN4t1E 8 pdN2t1 Ul H pdN4t1E "1 T 2 $

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S+'ESSES - +6E S&6' AL &?'+ ?-:or the hemispherical ends havin! thic#ness t2,we have

f hW H f l

W H f H pdN4t2

+herefore, hoop stress, f h H pdN4t2And

Lon!itudinal stress, f l H pdN4t2+hen

6oop strain, UhWH f hNE T f lNE H pdN4t2E T pdN4t2E UhW H pdN4t2E "1 8 $

Lon!itudinal strain,U lW H f lWNE 8 f hWNE H pdN4t2E 8 pdN4t2E Ul W H pdN4t2E "1 8 $

+herefore for spherical portionUhW H UlW

At the .unction of c)lindrical and spherical portion Uh H UhW

&dN4t1E "2 8 $ H pdN4t2E "1 8 $t2Nt1 H "1 8 $N"2 8 $

for steel,H %3+herefore,

t2Nt1 H BN1B

+he ma imum hoop stress will then occur in the ends, i%e%f H pdN4t2 H "1BNB$ "pdN4t1$

/hich is !reater than the hoop stress fh in the c)linder% or e7ual ma imumstress t2 should e7ual to %0%

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ANALYTICAL DESIGN

OF METHANATOR

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2.1 GIVEN DATA

PARAMETETS!%

2B


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/or#in! temperature H 3 4 Desi!n temperature H 404 D

/or#in! pressure H 3 &si%!esi!n pressure H 430 &si%!

DIMENSIONS!%

nside diameter H 1 2X H 209 % mm

+an!ent to tan!ent len!th H 10 X H 3 1 mm+)pe of dished ends H 2:1 semi ellipsoidal6)drostatic test pressure H &si%!/elded .oint efficienc) H 1 K

orrosion allowance H 1% mm

MATERIAL!%

AS+< A3 B 511

CODE RECOMMENDED

AS


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2.3 METHANATOR AS A THIN

CYLINDER

As we #now that if the ratio of thic#ness to internal diameter i%e% tNd is lethan a*out 1N2 " % 0$, the c)linder is assumed to *e thin c)linder otherwiit would *e thic#%

or methanator this ratio will *etNd H 1%43 N1 2 H % 14 Z % 0

So we treat methanator as thin c)linder

So incase of methanator the radial stresses can *e ne!lected% And there will *e onl) circumferential or hoop stress Y lon!itudinal stress in themethanator% urther the !overnin! stress will *e the !reater of the two Y we *ase our desi!n on it%

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2.4 THIC NESS OF SHELLAccordin! to specifications in (582B "c$ which deals with the thic#ness ofshells under internal pressure and clause @c with the c)lindrical shells,!ives formulae for the thic#ness *ased on either lon!itudinal .oint orcircumferential .oint%

a$ ' (< E'-+ AL S+'ESS "L?-5 +( -AL J? -+S$

t means that the !overnin! stress will *e thecircumferential stress "hoop stress$ in the lon! seam% or this it has to satisfthat & does not e ceed %3 0SE % n which case we shall use the followinformulae for thic#ness of shell

t H &'N "SE 8 % &$

*$ L?-5 +( -AL S+'ESS " '(< E'E-+ AL J? -+S$

t means that the !overnin! stress will *e the lon!itudinalstress in the circumferential .oint% or this it has to satisf) that & does note ceed 1%20SE% ?' if the circumferential .oint efficienc) is less than than Mthe lon!itudinal .oint efficienc)% n which case we use the formula forthic#ness is

t H &'N "2SE [%4&$As for methanator

& Z %3 0SE

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430 Z %3 0"1 394%9 $ "1% $ 430 Z 312% Satisfied

therefore hoop stress will *e !overnin! therefore desi!n is *ased on thelon!itudinal .oint Y we find the thic#ness as follows

t H &' N "SE T % &$/here

t H min% re7uired thic#ness of shell, in& H internal desi!n pressure, psi' H inside radius of shell, inS H ma % Allowa*le stress, psiE H .oint efficienc) "min$

&uttin! the values in the a*ove e7uation for methanator%Allowa*le stress for the material to *e used is also !iven "1 394%9 psi$

t H "430$ "01$ N ""1 394%9 $ "1% $ T " % $ "430$ t H 1%3B0X t H 1%3B0X [ corrosion allowance

t H 34%9 [ 1% mm t H 3 %0 mm

t H 1%43 BX

we shall ta#e a plate of 1 MX for safet)

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2.5 THIC NESS OF 2:

ELLIPSOIDAL HEAD

t will *e found *) (5832 "d$ which states +he re7uired thic#ness of a dished head of semi ellipsoidal form, in

which half the minor a is "inside depth of the head minus the s#irt$e7ualsone8forth of the inside diameter of the head s#irt, shall *e determined *)

t H & N "2SE T %2&$

An accepta*le appro imation of a 2: 1 Ellipsoidal head is one with a #nuc#le

radius of %1B and a spherical radius of %9 %

or methanator

t H "430$ "1 2$ N "2"1 394%9 $ "1% $ T " %2$ "430$$ t H 1%30 BX [ corrosion allowance

t H 1%30 BX [ "1% R %394X$ t H 1%419BX

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>nuc#le radius H %1B H 1B%34XSpherical radius H %9 H 91% X

/here H internal diameter in inches

2." OPENINGS IN A PRESSURE VESSEL

+he clause of the code concernin! with the desi!n of openin!s is (583 "a$

"*$a$shape of openings

1$ ?penin!s in c)lindrical or conical portions of vessels, or in formedheads, shall prefera*l) *e circular, elliptical or round openin! e ceeds twicethe short dimensions, the reinforcement across the short dimensions shall *eincreased as necessar) to provide a!ainst e cessive distortion due to twistin!moment% "+he openin! made *) a pipe or a circular no==le, the a is of whicis not perpendicular to the vessel wall or head, ma) *e considered aselliptical openin! of desi!n purposes$

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2$ ?penin!s ma) *e of other shapes than those !iven in "1$ a*ove, and allcorners shall *e provided with a suita*le radius% /hen the openin!s are ofsuch proportions that their stren!th cannot *e computed with assurance ofaccurac), or when dou*t e ists as to the safet) of a vessel with suchopenin!s, the part of the vessel affected shall *e su*.ected to a proof

h)drostatic test as prescri*ed in (581 1%

*$ size of openings

1$ &roperl) reinforced openin!s in c)lindrical shells are not limited as tosi=e e cept with the followin! provisions for desi!n% +he rules in (583throu!h (5843 appl) to openin!s not e ceedin! the followin!: for vessels

in% in diameter and less, one half vessel diameter, *ut not to e ceed 2 ifor vessel over in% in diameter, one third the vessel diameter, *ut not toe ceed 4 in% or openin!s e ceedin! these limits, supplement rules of 18Bshall *e satisfied in addition to (583 throu!h (5843% 2$ &roperl) reinforced openin!s in formed heads and spherical shells arenot limited in si=e% or an openin! in end closure, which is lar!er than one

half of inside diameter of the shell, various alternatives to reinforcementma) also *e used%

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As there are five openin!s in the methanator all of them are in its heads% +wof them are elliptical Y three are circular%As for methanator there is the ma imum openin! is of si=e 24X Y

24 Z 1N3"1 2$

24 Z 34 to4So we use (583 for openin!%

2.# SELECTION OF FLANGES

/e #now that openin!s of si=e 2%0X or lar!er shall *e flan!ed Y we shall useflan!es with raised face%

or methanator , all the flan!es would *e of ratin! l* which are selectedfrom the pressure8temperature ratin! "A-S 1 %0819 1$ or desi!n pressure of 430 psi%! Y desi!n temperature of D , which will *e roundeoff to 0 Y 030psi%! ta*le attached%

?ther specification of the flan!es accordin! to their pipe si=es are !iven"hi!h li!hted$ for l* flan!es in the ta*le attached%

3B


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LE-5+6 ? S+( ?L+S

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2.8 THIC NESS OF S IRT OR DESIGN OF

SUPPORTS

A s#irt is the most fre7uentl) used and the most satisfactor) support forvertical vessels% t is attached *) continuous weldin! to the head and usuall)the re7uired si=e of this weldin! determines the thic#ness of the s#irt%

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i!ures A and show the most common t)pe of s#irt to head attachment% ncalculations of the re7uired weld si=e, the values of the .oint efficienc) !iven *) the ode "(/ 12$ ma) *e used%"(5804 YA&&E- G 5$

t H 12


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(sin! e tremel) hi!h s#irt, the stresses at the *ase ma) !overn% +o calculatethe re7uired thic#ness of s#irt, in this case the a*ove formula can *e used%+he moment and wei!ht shall *e ta#en into consideration at the *ase and .oint efficienc) will *e ta#en as 1% %

or methanator the wei!ht of the vessel used is as appro imated later% And

we are ta#in! into account the moments due to two forces firstl) due toearth7ua#eAnd secondl) due to wind% /hichever is !reater should *e used%As the moment at the s#irt to head .oint due to seismic load is !reater asindicated *) the calculations later% so we shall use < due to earth7ua#e

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+he a*ove calculations are from the @ Pressure vessel hand book by Megyesy

+o verif) our calculations we also used the formula from another *oo# of@ Dennis R. Moss these calculations are as under

THIC NESS REQUIRED AT OPENING OF S IRT

+here are five openin!s in the methanator s#irt *ut the *i!!est openin! is of24X in dia% +herefore the desi!n is *ased on this openin!

5 H width of openin! in inches H 24X H width of s#irt H 1 4% B0X < *H moment at *ase, in8l* H B932B%39 l*ft "earth7ua#e / *Hwei!ht of vessel at *ase, l* H 41 BB% B l* ) H minimum specific )ield stren!th, psi H 349 %430psi f * H *endin! stress, psi H \

f * H 1 N "I 835$ R ^4 < *N [ / *_

-ow after puttin! the values in a*ove formula Y solvin! we !et the value of *endin! stress as follows

f * H 1 02%94B0 psi -ow the thic#ness of s#irt can *e found *) two formulae the !reater of thetwo values must *e ta#en

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ts# H f *N R) H 1 02%94B0 N R349 %430ts# H % E8

?'

ts# H "f * N 4 4 , $1N2

ts# H % 19X+he !reater value should *e ta#en%" % 19$/hich nearl) e7ual to the thic#ness found earlier

DETERMINE ALLO$ABLE LONGITUDANAL STRESSES!%

+E-S ?-,

St H lesser of %) or 1%33S

St H %) or St H 1%33S H % R349 %430 H 1%33R 1 394%9

S ' ( 20993.0" H 21 0%3 4

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L?-5 +( -AL ?' ES

lt H ^4 R< * N IR 2_ T ^/ * N IR _

lt H 1323% 3B T 12B%1

lt H 1190% l*Nin lc H "8$ lt] lcH 8 140 %2 0 l*Nin

+herefore s#irt thic#ness re7% at *ase

t s# H ltN St ?' H lc N Sc

H 1190% N 2 993% ?' H 140 %2 0 N 11 01%14

H % 0 X ?' H %12X

+he !reater of the two values is ta#en i%e% %12X

2.9 METHANATOR IS TO BE SUB*ECTED TO THE

FOLO$ING INDS OF LOADINGS

rom the list of the loadin!s on a pressure vessel !iven in (5822,methanator is lia*le to *e su*.ected to the followin! loads%

nternal pressure

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/ei!ht of the vessel and normal contents under operatin! or test

conditions"this includes additional pressure due to static head ofli7uids$/ei!hts of various attachments

/ind Y seismic reactions

2.10 STRESSES IN RESPONSE TO DIFFERENT LOADS

a$ (E +? -+E'-AL &'ESS('E As we are treatin! methanator as a thin c)linder so the values of hoop

stress Y lon!itudinal stress are calculated as under +herefore radial stresses are i!nored "ver) small$ so we consider thefollowin! primar) mem*rane stresses%

6oop Stresses

Lon!itudinal Stresses

6??& S+'ESSES "S 1$

h H &d N2t

H "430$ "1 2$ N 2"1%43 1$ H 1042 % l*Nin2

L?-5 +( -AL S+'ESS "S 2$

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l H &d N 4t H "430$ "1 2$ N 4"1%43 1$ H BB13%3 2 l* N in2

As hoop stress is !reater so desi!n is *ased on hoop stress%

)+ STRESS DUE TO $EIGHT OF VESSEL ,

ATTACHMENTS

t is assumed that wei!ht of the vessel and its attachments results incompressive stress onl) Y eccentricit) doesnFt e ists and the resultin! force

coincides with the a is of the vessel%+he wei!ht shall *e calculated for the various conditions of the tower asfollows%

A% Erection wei!ht% ?peratin! wei!ht% +est wei!ht

+he compressive stress due to the wei!ht is !iven *)

S H / N ct 888888888888888888888888888888888888888888/here

S H unit stress, psi/ H wei!ht of vessel a*ove the section under consideration, l*c H circumference of shell or s#irt on the mean diameter, int H thic#ness of shell or s#irt, in

+he wei!hts of different vessel elements are !iven in the ta*les attached%

$EIGHT OF METHANATOR

4


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A+ ERECTION WEIGHT

1$ S6ELLH10 R12%0"++L$ H19850 lb

2$ SE< ELL &S? AL 6EA S H 0003R2 H11106 lb

3$ LA-5ES " $ H "S bE$ H wt% of weld nec# [wt% of slip

[studs A "24X$ H 9BB [ B [ 3 0 Aa "12X$ H 22 "/ -$ A+ Y + "2X$ H 4"1 $ [ 2"4%0$ `/%- [ S+( S] "12X$ H 22 "/-$ " X$ H B3[ [3

+?+AL /E 56+ ? LA-5ES H 2908 lb

4$ & &ES "assumin! S 6% 1 $ El*ow "12X$ H40 l* 2 pipes "1MX$ H 2R4%9 l*Nft R 1

&ipe "2X$ H B%0 l*Nft R "9N12$&ipe " X$ H 40%3 R "1 0N12$

+?+AL /E 56+ (E +? & &ES Y EL ?/ H 1008.775 lb

0$ &LA+ES "+here are 4 plates in the methanator upper manhole Y whichare 4X wide Y MX thic# Y also 3 lon!$ /ei!ht of one plate H % R3 /ei!ht of 4 plates H 2 %4R4 H 1% l*%

4B


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$ -S(LA+ ?- "/e shall use an insulation of mineral wool of thic#ness 2MX%+he wei!ht of insulation !iven in the ta*le is in pounds per cu*ic feet so inorder to !et the wei!ht of insulation we will have to calculate the volume of

insulation to *e used on methanator% or that we will 1st

have to find thecircumference of the vessel *ased on e ternal diameter%

Volume of insulation on shell H ++L [ circumference [ thic#ness H 12%0 [ I R o [ %2 3

H 12%0 [ 2B%44 [ %2 3 H B1%44 9%ft3

Volume of insulation on the heads H 1% 9 R 2 Rthic#ness R2 H 1% 9 R %B39 2R %2 3R2 H 34% 3 ft3

+?+AL V?L(


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+herefore, the erection wei!ht H3B9 4%43Bl*

$ ?&E'A+ -5 /E 56+

E'E + ?- /E 56+ H 3B9 4%43B l*

/E 56+ ?' ?&E'A+ -5 L ( H 0K ? +6E E'E + ?-/E 56+

H 1 99%22 l*+?+AL ?&E'A+ -5 /E 56+ ?


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+he minimum *asic wind speed for determinin! desi!n wind pressure shall *e ta#en from the map of wind speed%

esi!n wind pressure shall *e determined *) the followin! formula:8

& H 7sR e R 7

/here, &H esi!n wind pressure, psf 7 s H /ind sta!nation pressure at the standard hei!ht of 3 feet asta*ulated:

B7 / / : - :; - +; - ? 13 1B 21 2 31 3B 44

7 H &ressure coefficient "shape factor$: 'ound or elliptical towers8888888888888888888888888888 %

e H om*ined hei!ht, e posure and !ust factor coefficient as ta*ulated:

6ei!ht a*ove !round,ft%

oefficient "e$

E posure E posure

82 1%2 %B2 84 1%3 %4 8 1%0 1%

81 1% 1%11 810 1% 1%310 82 1%9 1%4

E posure 888888888888888888888+he most severe e posure

E posure 888888888888888888888 ntermediate e posure

0


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ht H distance from *ase to section under consideration, ft H 12% 6 H len!th of vessel section, ft H20%33 < H


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/here, H ?utside diameter of vessel, ft% H %B0l*

6 H Len!th of vessel includin! s#irt, ft% H 2B%41 ft

5 H 32%2 ft% N sec2

acceleration + H +hic#ness of s#irt at the *ase, in% H % 1X V H +otal shear, l*%, H 32 3% 4 l* "calculated ahead$ /H /ei!ht of tower, l*% H 41 BB% B l*

wH wei!ht of tower per foot of hei!ht, l*% H 10 l* "from ta*le$&uttin! values to !et period of vi*ration for methanator

+ H % 2 0"2B%41 N %B0$2R"10 R %B0N% 1$M

+ H %9 sec -ow allowa*le period of vi*ration

+a H % `wR6 N VR!] M

+a H 2% sec

As O+F is less than O+aF hence the condition is satisfied

STRESS DUE TO EARTHQUA E

+he loadin! condition of the tower under seismic forces is similar to thatof the cantilever *eam when the load increases uniforml) towards thefree end

04


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?' H 6ori=ontal force factor "use 2% for vessels$ < H


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+herefore stress due to earth7ua#e

Se7 H 12R


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om*ined stress at the head to s#irt .oint on the vessel in operatin!

conditions= 15412.46 psi

2.12 COMPARISON+he !overnin! stress will *e tensile as shown *) the positive si!n, which is

lesser than allowa*le stress of the !iven material at that particulartemperature

+herefore the desi!n issafe.

2.13 DESIGN OF ANCHOR BOLTS

Vertical vessels, must *e fastened to the concrete foundation, s#id or otherstructural frame *) means of anchor *olts and the *ase "*earin!$ rin!%

+6E -(< E' ? A- 6?' ?L+S +he anchor *olts must *e in multiple of 4 and for tall towers it is preferredto use minimum *olts%

SPACING OF ANCHOR BOLTS

+he stren!th of too closel) spaced anchor *olts is not full) developed inconcrete foundations% it is advisa*le to set the anchor *olts not closure thana*out 1 X %to hold this minimum spacin!, in the case of small diametervessel the enlar!in! of the *olt circle ma) *e necessar) *) usin! conical

s#irt or wider *ase rin! with !ussets%

A


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shown *elow in ta*le A% for corrosion allowance 1N of an inch should *eadded to the calculated diameter of anchor *olts%

or anchor *olts and *ase desi!n is descri*ed for methanator 1$ An appro imate method which ma) *e satisfactor) in a num*er of cases%

2$ A method which offers closer investi!ation when the loadin! conditionsand other circumstances ma#e it necessar)%

R Source &ressure Vessel 6and oo# *)

/e will use the appro imate method+he desi!n of anchor *olts is to assume the *olts replaced *) a

continuous rin! whose diameter is e7ual to the *olt circle%

09


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+he re7uired area of the *olts shall *e calculated for empt) conditionof tower%

?'


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*olt root area H 4% 1 s7% in

rom ta*le specimen no%HSA 193 B ma % allowa*le stress H 1 , psi

or chec#in! stress in anchor *olts

5iven,

olt circle dia% H 111% 2X Area with in the *olt circle H A * H I r 2 H9B %33 s7%in ircumference of *olt circle H I H 30 % X


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"+)pes of .oints to *e used for vessels in various services and undercertain desi!n conditions%$ (/82, (/83"c$%J? -+ E E- ES A- S+'ESS 'E ( + ?-S:

"Efficiencies of .oints at certain locations and reduced allowa*le stressto *e used in calculations of vessel components%$

+he data of the ta*le are *ased on the followin! ode re!ulations:ull, spot, partial radio!raphic e amination or no radio!raph) of A, , and

.oints% (/811or lon!itudinal stress calculation the efficienc) of partiall) radio

!raphed .oints is the same as for spot radio !raphed .oints%Seamless vessel sections and heads with ate!or) , or *utt .oints

that are spot radio !raphed shall *e desi!ned for circumferential stress usin!a stress value e7ual to 0K of the allowa*le stress value of the material;(/812"*$

/hen the .oints are not radio !raphed and for .oint efficienc), E thevalue in column of ta*le @+)pes of welded .oints are used, in all otherdesi!n calculation, a stress value e7ual to K of the allowa*le stress valueof material shall *e used e cept for unsta)ed flat heads, etc% (/812"c$

+6E E ?-?


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ncreasin! the si=e of a fillet weld, its stren!th increases in direct proportion, while the deposited weld metal increases with the s7uare of itssi=e%

Lower 7ualit) weldin! ma#es necessar) the use of thic#er plate forthe vessel% /hether usin! stron!er weldin! and thinner plate or theopposite is more economical, depends on the si=e of vessel, weldin!e7uipment, etc% this must *e decided in each particular case%

/EL -5 ?-


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3%2 ANSYS INPUT METHODS GUI " G ap!i"al #se inte fa"e #

COMMAND !INDO!

INPUT" $ata # FILE


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3.4 ANALYSIS OF METHANATOR UNDER

INTERNAL PRESSURE USING $SHELL 5 %

B


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3.5 ANALYSIS OF METHANATOR THROUGH COMMAND!INDO!

&PREP7

&TITLE' METHANATOR

ANTYPE'STATIC ET'1'SHELL51 R'1'1.43( MP'E)'1'3*E6 MP'NU)Y'1'.3 N'1'51 N'2'51'1* E'1'2 CP'1'U)'1'2 + COUPLE RADIAL DIRECTION D'1'UY'''''U,'ROT, D'2'ROT, F'2'FY'35545*7.( + CAP FORCE SFE'1'1'PRES''435 + INTERNAL PRESSURE FINISH &SOLU

OUTPR'ALL'1 SOLVE FINISH &POST1

ETABLE'STRS-HOOP'NMISC'6 ", DIR# ETABLE'STRS-LONGI'NMISC'7 "Y DIR#

3.6 ANALYSIS OF METHANATOR THROUGH GUI

Since the material of methanator is same throu!hout therefore we will useistroptropic material for structural anal)sis% +he units specified in -" +($ %

B1


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MAIN MENU /SOLUTION / NE! ANALYSIS / STATIC

D E F I N IG T H E E L E M E N T T Y P E

As we are usin! @Shell 01 for the anal)sis of methanator therefore, define

thhe element t)pe as follows,

MAIN MENU/PREPROCESSOR/ELEMENT TYPE /ADD&EDIT&DELETE/SHELL51

B3


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MAIN

MENU/PREPRCESSOR/REALCONSTANTS/ .43(0

D E F I N I G M AT E R I A L P R O P E RT I E S

or isotropic materials, the properties remains the same in ever) direction%6ere we have entered the )oun!Fs modulus "3 e $, the densit) of material is" %2 $, the posionFs ratio " %3$% all of these values are !iven in the ta*lematerial for the methanator%

MAIN MENU/PREPRCEESOR/MATERIAL PROP/CONSTANT ISOTROPIC

B0


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+he two nodes are plotted at a distance of 01 inches from the ori!in which isinfact, the radius of methanator% +hr hei!ht of element is ta#en at 1 inches%

M1 / 8 8 ;/ 8 1< / => ;/I 1 < ? CS

B


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C R E AT I N G E L E M E N T

MAIN MENU/PREFERENCES/CREATE/ELEMENTS/THRUNODES

BB


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A P P LY IN G C O N S T R A I N T S

MAIN MENU/SOLUTION/APPLY/DISPLACEMENT

B


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B9


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n order to see the effect of lon!itudinal component of pressure which causesthe lon!it)udinal stress in the shell mem*rane, lon!itudinal force is appliedas caculated earlier in addition to the internal pressure which is 430 psi%

MAIN MENU/SOLUTION/APPLY/FORCE&MOMENT/FY

1


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2


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after creatin! element of the methanator material% And after appl)in! the *oundar) conditions Y loads % +he element is read) for the solution% Asshown on the previous pa!e%

solve the element as shown *elow%

MAIN MENU/SOLUTION/SOLVE CURRENT LS

3


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P O S T P R O C E S S I N G

t is the environment where the results of the anal)sis can *e listed or ploted%or our case the resuts are ploted as follows% As we are interested in the

stress therefore we have listed or plotted the e7uivalent stress or von mises%

MAIN MENU/ GENERAL POSTPROCESSOR/LISTRESULTS/NODAL SOLU/STRESS COMPONENTS

RESULTS

4


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MAIN MENU/GENERAL POST PROCESSOR/LISTRESULTS/NODAL SOLU/STRESS PRINCIPALS

RESULTS

0


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MAIN MENU/GENERAL POSTPROCESSOR/PLOTRESULTS/NODAL SOLU/STRESS VON MISES


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3.7 TO FIND THE HOOP AND LONGITUDINAL STRESSH - ' / ) 7 '< %7 / , /'=:/ 7 ' / ) 7 7 / .S'7 '/ ? 7/ = '< ? / -7'< / ? : ' '< < - 7 :

/'=:/ 7 ' .GEN. POSTPROC/ELEM. TABLE/DEFINE TABLE/STRESS HOOP NMISC'6

888888888888888888888888888888888888 /STRESS-LONG NMISC 7

B


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T O S E E T H E LONGITUDINAL S T R E S S/BY SE UENCE NMISC'7

THE LONGITUDINAL STRESS IS OBTAINED.

9


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3 . ( D I S P L A C E M E N T S O F T H E 4 D O F ;

9


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COMPARISON&

CONCLUSION

91


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4 . M E M B R A N E S T R E S S E S IN

M E T H A N AT O R

+he mem*rane stresses i%e hoop Y lon!itudinal stresses ploted are in pound per s7uare inch%

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4 . 2 C O M PA R I S O N O F A N S Y S @ A N A LYT I C A L

S O L U T I O N

As it is evident from the chart that our lon!itudinal stress is e actl) the same *ut the circumferential stress varies sli!htl) owin! to roundin! off data%

C O N C L U S I O N

F=8 ;2 ? ; > < ASME SECTION (

> ? ; = 1 2: 2? ; < ;2 : :


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REFERENCES

SECTION VIII RULES FOR CONSTRUCTION OF PRESSURE

VESSELS DIVISION 1

PRESSURE VESSEL HANDBOO Seventh Edition !"

!" # $. M "% &%

#RESSURE $ESSE% DESIGN MANUA%

by DENNIS R& MOSS

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90


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9B


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9


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99


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1 1


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1 2


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1 3


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1 4


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design procedure for pressure vessel

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