design procedure for pressure vessels foundation design

8/12/2019 Design Procedure for Pressure Vessels foundation design

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TABLE OF CONTENTS

S. NO TITLE PAGENO

. INTRODUCTION TO PRESSURE VESSELS4

1.1. BASIC TERMINOLOGIES USED 5

1.2 CYLINDERS AND SPHERS 19

2. ANALYTICAL DESIGN OF METHANATOR26

2.1 GIVEN DATA 28

2.2 REQUIRED DIMENTIONS OF METHANATOR 29

2.3 METHANATOR AS A THIN CYLINDER 30

2.4 THICNESS OF SHELL 32

2.5 THICNESS OF 2!1 ELLIPSOIDAL HEAD 34

2." OPENING IN THE PRESSURE VESSELS 35

2.# SELECTION OF FLANGES 3#2.8 THICNESS OF SIRT OR DESIGN OF SUPPORTS 39

2.9 LOADINGS 44

2.10 STRESSES IN RESPONSE TO DIFFERENT LOADS 45

a) INTERNAL PRESSURE

45

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b) 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 ANSYS67

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

4. COMARISION AND CONCLUSION92

4.1 MEMBRENE STRESSE IN METHANATOR 93

4.2 COMARISION OF ANSYS AND ANALYTICAL SOLUTION 94

4.3 CONCLUSION 9"

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

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

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. BASIC TERIMINOLOGIES USEDVESSEL:

A container or structural envelope in which materials are processed,treated, or stored; for eample, pressure vessel, reactor vessel, a!itator

vessel, 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 shear

strain% +he word strain is commonl) used to connote unit strain%

S+'ESS:

nternal force eerted *) 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 calledshear stress; when the forces are

normal to the plane the stress is called normal stress; when the normal stress

is directed toward the part on which it acts is called compressive stress;

when it is directed awa) from the part on which it acts it is called tensile

stress.

0


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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 revolution

endin! stress

Shear stress

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

Shape of the vessel

+E-SLE S+'E-5+6:

+he maimum stress a material su*.ected to a stretchin! load can

withstand without tearin!%

+E-SLE 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 of

these 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 stress

values 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!, electrosla!, and

electron *eam%

2% &ressure weldin! process: flash, induction, resistance, pressure

+hermit, and pressure !as%

CEL &?-+:

+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=ontal,

and the lower )ield point, which is the somewhat lower and almost constant

stress under which the metal continues to deform% ?nl) a few materials

ehi*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 eample, 4D or D%

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


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S+AL+C ? VESSEL:

"Elastic sta*ilit)$ +he stren!th of the vessel to resist *uc#lin! or

wrin#lin! due to aial 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 minor

distortions can satisf) the conditions which cause the stress to occur and

failure from one application of the stress is not to *e epected% Eamples of

secondar) stress are: !eneral thermal stress; *endin! stress at a !ross

structural discontinuit)%

&?SS?-SF'A+?:

+he ratio of lateral unit strain to lon!itudinal unit strain, under the

conditions of uniform and uniaial 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 AGS:

+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 different

directions%


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pressure to *e mar#ed on the vessel or 1 M the desi!n pressure *)

a!reement *etween the user and the manufacturer% "ode (5899$


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A+?' ? SAE+C:

+he ratio of the load that would cuse 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%

EE-+'+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!h

centroid%+he perpendicular distance from the line of action of the load to

either of principle central ais is the eccentricit) with respect to that ais%

EE-C ? A /ELE J?-+:

+he efficienc) of the welded .oint is epressed 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%

1


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ELAS+ L


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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 eceptions, the components are usuall)

metallic elements%

1


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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 is

uniforml) distri*uted% All the a*ove mentioned vessels are classified as

c)linders or spheres%

+6- CL-E':

f the ratio of the thic#ness to the internal diameter i%e% tNd is less thana*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 than

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$

'(


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

+he stress which acts normal to circumference and parallel to the ais

of the c)linder is called lon!itudinal stress% t is denoted *) fl%

'AAL S+'ESS:

+he stress which acts in a direction perpendicular to the internal

surface is called radial stress% t is denoted *) fr% 'adial stress is ver) small

as compared to fl and fhin case of thin c)linder and is therefore i!nored%

2


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A-ALCSS ? +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 applied

internal 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 prPQL

Vertical component of this force H prPQL SinQ

+otal vertical force HprL 1SinQPQ

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

H pdL e7%"1$

ut

dL H hori=ontal pro.ected area%

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l H pdN4t e7% "$

omparin! "A$ and "$

l H1N2 fh

+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%e%fhH fl H f

ross8sectional area H I N4d2

urstin! force H pR I N4d2

'esistin! force H stress R resistin! area

H f R dt

or e7uili*rium of shell

urstin! force H resistin! force

& R I N4d2 H f R dt

f H pdN4t

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CL-E'AL S6ELL /+6 6E


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S+'ESSES - +6E S&6'AL &?'+?-:

or the hemispherical ends havin! thic#ness t2, we have

fhW

H flW

H f H pdN4t2+herefore, hoop stress, fhH pdN4t2

And

Lon!itudinal stress, fl H pdN4t2

+hen

6oop strain, UhW H fhNE T flNE H pdN4t2E T pdN4t2E

UhWH pdN4t2E "1 8$

Lon!itudinal strain,UlWH flWNE 8 fhWNE H pdN4t2E 8 pdN4t2E

Ul WH pdN4t2E "1 8$

+herefore for spherical portion

UhW H UlW

At the .unction of c)lindrical and spherical portion

UhH UhW

&dN4t1E "2 8$ H pdN4t2E "1 8$t2Nt1H "1 8 $N"2 8 $

for steel,H %3

+herefore,

t2Nt1H BN1B

+he maimum hoop stress will then occur in the ends, i%e%f H pdN4t2H "1BNB$ "pdN4t1$

/hich is !reater than the hoop stress fh in the c)linder% or e7ual maimum

stress t2should e7ual to %0%

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ANALYTICAL DESIGN

OF METHANATOR

2


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2.1 GIVEN DATA

PARAMETETS!%

2B


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/or#in! temperature H 34 D

esi!n temperature H 404 D

/or#in! pressure H 3 &si%!

esi!n pressure H 430 &si%!

DIMENSIONS!%

nside diameter H 12X H 209% mm

+an!ent to tan!ent len!th H 10X H 31mm

+)pe of dished ends H 2:1 semi ellipsoidal

6)drostatic test pressure H &si%!

/elded .oint efficienc) H 1 K

orrosion allowance H 1% mm

MATERIAL!%

AS+< A3B 511

CODE RECOMMENDED

AS


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2.2 REQUIRED DIMENSIONS OF

METHANATOR

+he 7uantities or dimensions that are to *e determined for desi!nin! are

listed *elow

I +hic#ness of shell "accordin! to (5 82B"c$$

II +hic#ness of 2:1 semi ellipsoidal head "accordin! to (5832"d$$

III ?penin!s in the pressure vessel as per re7uirement "accordin! to

(583 "*$ "1$ "2$$

IV Selection of flan!es "accordin! to (5844 Y (5811 "a$ "2$$V +hic#ness of s#irt or desi!n of supports%"accordin! to (5804 Y

appendi 5$

VI Specif) different #inds of loads "(5822$

VII ind stresses in response to different loads%

VIII om*ination of stresses%

I& omparison of stresses with allowa*le stress of material%

& ?penin!s in s#irt

&I esi!n of anchor *olts

&II esi!n of *ase rin!%

&III /eldin! specification for


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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 less

than a*out 1N2 "%0$, the c)linder is assumed to *e thin c)linder otherwise

it would *e thic#%

or methanator this ratio will *e

tNd H 1%43N12 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 the

methanator% 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 THICNESS OF SHELL

Accordin! to specifications in (582B "c$ which deals with the thic#ness of

shells under internal pressure and clause @c with the c)lindrical shells,

!ives formulae for the thic#ness *ased on either lon!itudinal .oint or

circumferential .oint%

a$ '(


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430 Z %30"1394%9$ "1%$

430 Z 312% Satisfied

therefore hoop stress will *e !overnin! therefore desi!n is *ased on the

lon!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, in

S H ma% Allowa*le stress, psi

E 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 "1394%9 psi$

t H "430$ "01$ N ""1394%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%43BX

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

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2.5 THICNESS OF 2:ELLIPSOIDAL HEADt will *e found *) (5832 "d$ which states

+he re7uired thic#ness of a dished head of semi ellipsoidal form, in

which half the minor ais "inside depth of the head minus the s#irt$e7uals

one8forth of the inside diameter of the head s#irt, shall *e determined *)

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

An accepta*le approimation 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$ "12$ N "2"1394%9$ "1%$ T "%2$ "430$$

t H 1%30BX [ corrosion allowance

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

t H 1%419BX

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>nuc#le radius H %1B H 1B%34X

Spherical 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 formed

heads, shall prefera*l) *e circular, elliptical or round openin! eceeds twice

the short dimensions, the reinforcement across the short dimensions shall *e

increased as necessar) to provide a!ainst ecessive distortion due to twistin!

moment%"+he openin! made *) a pipe or a circular no==le, the ais of which

is not perpendicular to the vessel wall or head, ma) *e considered as

elliptical 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 all

corners shall *e provided with a suita*le radius% /hen the openin!s are of

such proportions that their stren!th cannot *e computed with assurance of

accurac), or when dou*t eists as to the safet) of a vessel with such

openin!s, the part of the vessel affected shall *e su*.ected to a proof

h)drostatic test as prescri*ed in (5811%

*$size of openings

1$ &roperl) reinforced openin!s in c)lindrical shells are not limited as to

si=e ecept with the followin! provisions for desi!n% +he rules in (583

throu!h (5843 appl) to openin!s not eceedin! the followin!: for vessels

in% in diameter and less, one half vessel diameter, *ut not to eceed 2

in%; for vessel over in% in diameter, one third the vessel diameter, *ut not

to eceed 4 in% or openin!s eceedin! these limits, supplement rules of 18

B shall *e satisfied in addition to (583 throu!h (5843%

2$ &roperl) reinforced openin!s in formed heads and spherical shells are

not 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%

+wo of them are elliptical Y three are circular%

As for methanator there is the maimum openin! is of si=e 24X Y

24 Z 1N3"12$

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 use

flan!es with raised face%

or methanator , all the flan!es would *e of ratin! l* which are selected

from the pressure8temperature ratin! "A-S 1%08191$ or desi!n

pressure of 430 psi%! Y desi!n temperature of D, which will *e rounded

off 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

3


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2.8 THICNESS OF SIRT OR DESIGN OF

SUPPORTS

A s#irt is the most fre7uentl) used and the most satisfactor) support for

vertical 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%

39


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i!ures A and show the most common t)pe of s#irt to head attachment% n

calculations 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! etremel) hi!h s#irt, the stresses at the *ase ma) !overn% +o calculate

the 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 approimated later% And

we are ta#in! into account the moments due to two forces firstl) due toearth7ua#e

And 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 as

indicated *) 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. Mossthese calculations are as under

THICNESS REQUIRED AT OPENING OF SIRT

+here are five openin!s in the methanator s#irt *ut the *i!!est openin! is of

24X 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 14%B0X


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ts#H f*N R) H 102%94B0 N R349%430

ts#H %E8

?'

ts#H "f*N 44,$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?-,

StH lesser of %)or 1%33S

St H %) or St H 1%33S

H %R349%430 H 1%33R 1394%9

S' ( 20993.0" H 210%34

?


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L?-5+(-AL ?'ES

ltH ^4R


45/106

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

conditions"this includes additional pressure due to static head of

li7uids$

/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 the

followin! primar) mem*rane stresses%

6oop Stresses

Lon!itudinal Stresses

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

h H &d N2t

H "430$ "12$ N 2"1%431$

H 1042% l*Nin2

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

40


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l H &d N 4t

H "430$ "12$ N 4"1%431$

H BB13%32 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 in

compressive stress onl) Y eccentricit) doesnFt eists and the resultin! force

coincides with the ais of the vessel%

+he wei!ht shall *e calculated for the various conditions of the tower as

follows%

A% Erection wei!ht

% ?peratin! wei!ht

% +est wei!ht

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

S H / N ct 888888888888888888888888888888888888888888888 "a$

/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, in

t 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$ S6ELLH10R12%0"++L$ H19850 lb

2$ SE


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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 in

order 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 eternal diameter%

Volume of insulation on shell H ++L [ circumference [ thic#ness

H 12%0 [ I R o[ %23

H 12%0 [ 2B%44 [%23

H B1%449%ft3

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

H 1%9 R %B392R%23R2

H 34%3 ft3

+?+AL V?L(


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K of total wei!ht H 210%20

+herefore, the erection wei!ht H3B94%43Bl*

$ ?&E'A+-5 /E56+

E'E+?- /E56+ H 3B94%43B l*/E56+ ?' ?&E'A+-5 L( H 0K ? +6E E'E+?-

/E56+

H 199%22 l*

+?+AL ?&E'A+-5 /E56+ ?


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hei!ht are hi!her than those shown in the map, those hi!her values shall *e

the minimum *asic wind speed%

+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 7sReR7

/here,

&H esi!n wind pressure, psf

7 s H /ind sta!nation pressure at the standard hei!ht of 3 feet as

ta*ulated:

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

7H &ressure coefficient "shape factor$:

'ound or elliptical towers8888888888888888888888888888%

eH om*ined hei!ht, eposure and !ust factor coefficient as ta*ulated:

6ei!ht a*ove !round,

ft%

oefficient "e$

Eposure Eposure

82 1%2 %B284 1%3 %48 1%0 1%

81 1% 1%11810 1% 1%31082 1%9 1%4

Eposure 888888888888888888888+he most severe eposure

0


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Eposure 888888888888888888888ntermediate eposure

or the methanator we will ta#e a wind speed of 13 mph, so the value of

7sH44psf

eH %8888888888888888888888888or circular vessel7H % 888888888888888888888888ntermediate eposure Y vessel hei!ht of

2ft

+here fore the value of wind pressure usin! the a*ove formula will *e;

& H 2%1 psf

/e will ta#e the wind pressure 3 psf%

(A-++ES ?'


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E H Efficienc) of the welded .oints H 1%

h1H lever arm, ft H 6 N 2 H 12%

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 sec2acceleration

+ H +hic#ness of s#irt at the *ase, in% H%1X

V H +otal shear, l*%, H 323%4 l* "calculated ahead$

/H /ei!ht of tower, l*% H 41BB%B l*

wH wei!ht of tower per foot of hei!ht, l*% H 10l* "from ta*le$

&uttin! values to !et period of vi*ration for methanator

+ H %20"2B%41 N %B0$ 2R"10R%B0N%1$ M

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

+aH % `wR6 N VR!]M

+aH 2% sec

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

STRESS DUE TO EARTHQUAE

(A-++ES ?'


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+he loadin! condition of the tower under seismic forces is similar to that

of the cantilever *eam when the load increases uniforml) towards the

free end

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

< H


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Shear H %3B0R1R2R%R1%0R41BB%B

V H 323%4l*

t H %BR+RV H210%24

%20V H %91

As condition is that tshould not eceed %20V so it is satisfied for

methanator

+herefore,


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om*ination of stresses will *e as follows

' := ' 7'=7

' := ' /'7 -=

%' := ' /


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to use minimum *olts%

SPACING OF ANCHOR BOLTS

+he stren!th of too closel) spaced anchor *olts is not full) developed in

concrete foundations% it is advisa*le to set the anchor *olts not closure than

a*out 1X %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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R Source &ressure Vessel 6and oo# *)

/e will use the approimate method

+he desi!n of anchor *olts is to assume the *olts replaced *) a

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

+he re7uired area of the *olts shall *e calculated for empt) condition

of tower%

?'


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Stress in Anchor olt psi% S* S*H+*Na-

/here,

A* H area within the *olt circle, s7% 8 in%

* H ircumference of *olt circle in%

< H


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5iven,

olt circle dia% H 111%2X

Area with in the *olt circle H A*H I r2H9B%33 s7%in

ircumference of *olt circle H I H 30%X


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n man) cases the accessi*ilit) of the .oint determines the t)pe of

weldin!% n a small diameter vessel "under 1824 inches$ from the inside,

no manual weldin! can *e applied% (sin! *ac#in! strip it must remain in

plate% n lar!er diameter vessels if a man wa) is not used, the last "closin!$

.oint can *e welded from outside onl)% +he t)pe of weldin! ma) *e

determined also *) the e7uipment of the manufacturer%

?E 'E('E


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or 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 the

value in column of ta*le @+)pes of welded .oints are used, in all other

desi!n calculation, a stress value e7ual to K of the allowa*le stress value

of material shall *e used ecept for unsta)ed flat heads, etc% (/812"c$

+6E E?-?


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opposite 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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ANALYSIS

BY

ANSYS

B


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3. ANSYSA-SCS is software of EA "inite Element Anal)sis$ which !ives )ou a

wa) to test )our model *efore manufacturin!% )ou can calculate stress,strain, displacement, thermal stresses, resonance, also optimum desi!n

parameters, points where our model *ecomes unsta*le and much more% An)

of seven anal)sis t)pes offered in A-SCS:

S+A+


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3%2 ANSYS INPUT METHODS GUI "Gap!i"al #se intefa"e# COMMAND !INDO! INPUT"$ata# FILE

9


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3%3

B


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3.4 ANALYSIS OF METHANATOR UNDERINTERNAL PRESSURE USING $SHELL 5 %

B1


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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 use

istroptropic material for structural anal)sis% +he units specified in -

"+($ %

B2


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MAIN MENUE / PREFERENCES / STRUCTURAL

n order to !ive title to our modal%

LE6A-5E ++LE


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MAIN MENU /SOLUTION / NE! ANALYSIS / STATIC

DEFINIG THE ELEME NT TYPEAs 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

B4


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DEFINING REAL CONSTANTSn @shell 01 we will onl) ta#e two nodes of the vessel material % as it is a a

2? case therefore the thic#ness of the vessel could *e entered in the real

constants% Since the shell is of uniform thic#ness and the dished ends are of

comparativel) less thic#er than the shell "as calculated in anal)tical desi!n$,

to compensate for the increase in stren!th due to *endin!% +herefore, the

thic#ness remains the same throu!hout the vessel%i%e% 1%43 in%

B0


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MAINMENU/PREPRCESSOR/REALCONSTANTS/ .43(0

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

MAIN MENU/PREPRCEESOR/MATERIAL PROP/CONSTANTISOTROPIC

B


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+he two nodes are plotted at a distance of 01 inches from the ori!in which is

infact, the radius of methanator% +hr hei!ht of element is ta#en at 1 inches%

M1 /88;/81;/I 1


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CREATING ELEMENTMAIN MENU/PREFERENCES/CREATE/ELEMENTS/THRUNODES

B


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APPLYING LOADS

1


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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

2


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3


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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/SOLVECURRENT LS

4


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

MAIN MENU/ GENERAL POSTPROCESSOR/LIST

RESULTS/NODAL SOLU/STRESSCOMPONENTS

RESULTS

0


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MAIN MENU/GENERAL POST PROCESSOR/LIST

RESULTS/NODAL SOLU/STRESSPRINCIPALS

RESULTS


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MAIN MENU/GENERAL POSTPROCESSOR/PLOT

RESULTS/NODAL SOLU/STRESSVON MISES

B


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3.7 TO FIND THE HOOP AND LONGITUDINAL STRESSH- ' / ) 7 '


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TO SEE THE STRESSES "HOOP @LONG#GEN.POSTPROC/LIST RESULTS/ELEM. SOLN/BY SEUENCENMISC'6

BY DOING THIS HOOP STRESS IS OBTAINED.

9


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TO SEE THE LONGITUDINALSTRESS/BY SEUENCENMISC'7

THE LONGITUDINAL STRESS IS OBTAINED.

9


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3.( DISPLACEM ENTS OF THE 4 DOF;

91


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COMPARISON

&

CONCLUSION

92


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4. MEMBR ANE STRESSES INMETHANATOR

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

93


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4.2 COMPARISON OF ANSYS @ ANALYTICALSOLUTION

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

CONCLUSIONF=8 ;2 ? ;> ?;= 12: 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%

byDENNIS R& MOSS

90


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9


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9B


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9


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99


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1


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11


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12


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13


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14


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10


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design procedure for pressure vessels foundation design

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