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IS: 9178 ( P a rt 1) 1 9 7 9( Reaff i rmed 2010 )

Indian Standard CRITERIA FOR DESIGN OF STEEL BINS FOR

STORAGE OF BULK MATERIALS

PART 1 GENERAL REQUIREMENTS ANDASSESSMENT OF LOADS

( First Reprint SEPTEMBER1998 )

UDC 624.953.042 [ 669.14 ) : 621.796.6

Copyright 1980

BUREAU OF INDIAN STANDARDSMANAK BHAVAN

, 9 BAHADUR SHAH ZAFAR MARGNEW DELHI 1 10 0 02

Gr 7 Ap ril 1980

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IS I 9178 Part I -1979

ndian tandard

CRITERI FOR DESIGN OF STEEL INS FOR

STOR GE OF ULK M TERI LS

P RT I GENER L REQUIREMENTS NSSESSMENT OF LO S

Structural Engineering Sectional Committee, 5MBDC 7

Instrtutron of Engineers ( Ind ia) , Calcutta

CI nN1liJnDnU:;CT

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IS I 9178 Part I 1979

CotlJmllldjr lf l p ge 1 )

M mb R,pwmlmg5 1 P. K MALl,WK J . op Co Ltd, C a lc u tt aSur er 5 1\.11)I[ l OI\J.,,, ~ t . e lAuthnrrtv of Inchn Ltd. New DelhISIIRf S K. MUKHFI l JF: E Bridge Roof Co ( Indra ) Ltd, Howrah

Sn't B K ClIAT1 ' ' ' l tJJ1 :E Allernal.)SHl\] P N. BIIASKARAN NAIR Rarl India Technical an d E c o n o r m c s ~ < r \ ' I C e S ,

Ne w D lh.

Du cctor Gener.d, 1:>1 (E,-ojJi,, M L )

Bombay I'ort Tw A= -

R I f J U '1- ~ r . A[ n ESn m N K Rl l iC

Structural Engme ermg RCSCaf h L nt r e , Madras( Allanal )

M l n , , } of R.1JII, }'Fertil izer Corpor auon of India Ltd, Smdri

2

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FEBRUARY 1985MENDMENT N O

TO

IS : 9178 { Part I 1979 CRITERIA FO RDESIGN OF STEEL BINS FO R STORAGE

OF BULK MATERIALS

P RT I G N R L R QUIR M NTS N SSESSMENT

OF LO S

age 14, l use 6.2.1.2 ) - Substitute th e following for th e eXlstmgformula

MBDC 7

Pvinted a t Ne w India Prinrma Press, Khurja , India

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AMENDMENT NO.2 AUGUST 992TO

IS 9 78 Par t 1 ) : 979 CRITERIA FOR DESIGN OF STEELBINS FOR STORAGE OF BULK MATERIALS

PART 1 GENERAL REQUIREMENTS AND ASSESSMENTOF LOADS

Page 8 ig 5) -Inlcrchangc angle A With angle C m the hopper sketch

CED 7

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IS : 9178 Part I 1979

ndian tandard

CRITERIA FOR DESIGN OF STEEL BINS FORSTORAGE OF BULK MATERIALS

P RT I GENER L REQUIREMENTS NSS SSM NT OF LO S

F O R W O R

0.1 This I n di a n S t an d ar d (Par t I ) wa s aclopted by th e Indian StandardsInsti tution on 15 Mav 1')79, after th e draft finalized by tile Structur alEngincenng Sectional Committee ha d been approved y th e Structuredand Metals Division Council and th e Civil Engmcenng I \ ision Council.

0.2 Bins ar e known as silos i f they have circular or polvgonal shape 111plan. \Vhen , qu ar e o r rectangular plan they ar e known as bunkers. Inthis standard a bm shall m ean both Silo and blinker unless otherwisestated

0.3 The functions of IHilS as stor ag e -tructur e arr- very rrnpoi tant inpower stations, fertlhzer complexes, stt.cl plants, cement plants and Similarmdustrrcs fo r efficient storage and use of bulk matcn.rl both in granularand pm,d ry form. On th e agncultural fron t lun s M e used to store foodgralm lo r r-uvur mu theIr -upplv al l through thr- YCilr Bulk tlJrage ofmater i.ils in bins has certam advantages o ver other forms of storage.Thercfor c an I nd ia n S ta nd ar d on t hi s s ub je ct has been a long felt needand tlus standard 15 airned at i{lvmg th e necessary gUldanc .. in th e analysisand design of st ,.1 l un s f or stonng various matcr r. i ls of different characteristics and (low properties.0 Dins have b ee n d es ig ne d on th e basis o f ] anssen s Theory (wi thmodificanons to th e o rigrna l ), From expenmeutal lIlvnttg.lt1011S and astudy of th e pe l furmance of t he c xr su n g hrns It ha s been nouced that th epressure dis tr ibu tion influenced by th e size and shape of t he m at er ra l tobe stored ( that IS ;r

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IS r 9178 ( art ) - 1979

other mechanical rnr-ans. WIth research data available, this problem hasbeen successfully solved b y a do p ti ng mass flow or funnel flow bins whereth e shape o f th ' IJm h op pe r a n d size of th e openings ar e based on th e wI 0l,crtlc, of the s to red material.

0. 6 Tn order to ,J,.. With th e subject I n a n d f cl iv e manner this standardh.ls been prepared in three parts namely:

Part I General requirements an d assessment of loads

Part II Devign criteriaP art II I Bins designed for mass flow and funnel flow

0 .7 This stnndard keeps 1 Il view th e practices being fol lowed in thecountry and cbl \,here in this Iir ld Assistance ha s also been derived fromth e Iollowinq puhhcauons:

DIN 1055 ( Sheet 6 ) Design loads for building - Loads in silos/bins.Deutscher Normenausschuss.

PIF PEF K and V. F.NZI .L F Pressure Distribution in Bins ( inGerm m ) Verlr-z WlIhel rn Ernst Sohn, Berlm, Munchen. 1964.

L \ M I l F l l 1 F E ) The Theory and Practical Design of Bunkers TheBritish Construr.tional Steelwork Associations Ltd, London.

R I S J I R \ W) an d RaUTHF ( M. E .) Bins an d Bunkers for HandlingBulk M ue r mls. Trans-Tech Pubhcation, OhIO, OS/\

J E l lK l A. W Stor ac c an d Flow of Solids Bu l 123. 1964 UtahE I 1 ~ l I l C c n n ;Experiment Station, Umversrtv of Utah, Ut ah , USA. ill \ N J R. ) and c O L I J H ) New Design Crueria for Hopper an dbl m ron and Steel nginrer ctober 1961.

0.8 For till' purpo,e of dectdmg whether a particular requirement of thisstand.ij-] 1 \ complIed with, th e final value, observed or calculated, expressIng th e r esul t of a test or analysis, shall be rounded off I I I accordanceWith IS . 2-1960.

1. SCOPE

1.1 TillS st.rndar d (Pa r t I deals with th e general requirements an d

assessment of bin loads for granular an d powdery mater ia ls in d ifferentbill shapes.

2. TERMINOLOGY

2.0 Fo r the jJu1lw\e of this standard, the following defimuons shall apply.

R lle, for rounding of f nurm r ir al va lues , , , , d )

4

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IS: 9178 ( Par t I ) 19792.1 Aeration - A pr ocess n w hich air is moved through the storedmatcnals for ventilation.

2.2 Arching - A phe nomc nou In t i l U l n n ~th r em pt yi ng o f storedmaterial glVtng rise to Ior r na uo n o f arches of the material across th e bi nwalls.

2.3 Bin - A structure meant for storm: bulk mateual I n vertical directionWIth outlets for WIthdrawal either by gl avity alone or by gravIty assistedby flow promoting devices

2 3 Silo A bin cir cular or polygonal in plan.

2 3 2 Bunker - A bin whose ass section in plan is ~ q u l f eorr ectanuular.

2.4 Bin Asyrnmetr ica l - A bin in w hi ch t he o ut le ts ale asymmetricallyplaced to axes of th e bm,

2.5 Bin Interst ice - Bin formed out o f th e pace enclosed by a batteryof interconnected bins.

2.6 Bi n Loads - L oa d e xe rte d by a stored material on th e walls ofa bin.

2.7 Bu lk Sol id - Bulk of granular and powdery material.

2 7 Granular l \1a/erial-Material having mean particle size more than

o 2 m m, No cohesion between partic les is assumed.2 7 2 Powder Material - Material having mean paruclc size less than

6 mm

2. 8 Bunker Clos u re o r Gate - The closing anangement for the outletat th e bottom of the hopper for drscharging th e stored rnatei ial.

2.9 Consolidated Pressure - The normal p r ~ s u r eactrng on the bulksohd causing the particles to move closer together t he re by c ha ng in g th ebulk density and flow properties of the mate r ia l .

2.10 Food Grain - All cereals, pulles and rnillr ts, except orlsecds.

2.11 Funnel or Plug Flow - The flow pall er n I I I Inch the mat er ia lflows pnmarily in th e cent ral r eg ion of the b in o r h op pe r.

2.12 Hopper - The 1 )lluJIl cUllVClglllg pO uo u of t he b in .

2.13 Mass Flow - 1 Jow f w hi ch t he elllire mass matcu.il Ilows with.out st.ignation

5

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, 9178 ( Part I ) 1979

2.14 Poking Hole - Hole provided at sui table locat ion on th e sides forp ok in g t he stored marc rial either manually, mechanically, pneumaticallyor with s team.

2.15 Val le y A ng le - The angll of th e corner of p yr am id al h op pe rmeasured with respect to th e horrzontal plane.

2.16 Waist or Transi t ion - The junction of th e vertical wall, an d th es ides of hopper.

3. NOTATIONS3. 0 Fo r th e purpose of tlus s ta nd ar d, t he following notations shall have

th e meamng indicarcd a ~ a l ~each: = H lI o n let c ross sectional re of the stor ed material at

depth -::.

a = Side of a quart om 1 shorter Ide of a rectangular binb = Longe] siclc uf a rectangular bin

= In te rna l d iameter in a c ircu la r bmd = Maximum diameter of the circle that can be inscribed ill th e binh = Height of bi n

P8 = Pn SSUI r of .iir injected for pneumatic emptying of a bi nP = Pressu rc

I = Suffix ind a t l l l ~h, v or w corresponding to horizontal lateral ), vei ucal or wall Iricuon respectively

b = H O I izonta I I.Itl I.ll ) prcssure on th e Lin wall du e to storedmate r ia l depth

P = Vertical pressure 011 th e uouzonral cross-secuon of th e storedmaterial

P = Vertical 1 111 tran-ferred to the wall du e 1 fnction betweenmaterial >1'11 cd an d th e bm wall

F p 1 = Pressure Ohl . I I I1H] on th e wall of a inn imagmcd to be enlargedll plan as to make the eccentr ic openmg concentr ic

S = Bottom drametcr of InsertR fUU = Perrrnctet of the ci oss-scccion of the s to red matei ial at depth Z

W = Bulk density of the stor cd material::: = Depth below the levelled surface of the maximum possible fill

II I th e Inn ( see FIg. I )o= Angle of wal l friruon of th e stored marerral 011 the walls of th e

bill

6

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IS : 9178 ( Part I ) 1979

o = Slope of hopper wall with horizontal > = Angle of internal fricnon of th e stored material (for non-

cohesive materials it is also th e angle of repose)p = Coefficient of wall f ric tion ( ta n 8 = Pw(Ph )

= Coefficient of wall friction during fillingIJe = Coefficient o f wall [,-ict;on durmg e m p t ~ m g

I = pressure ratio ( PblP v At = Pressure ratio ( Ph/P v ) during fillingAe = Pressure ratio ( PhjP v ) dunng emptying.

? l . .: ,.10:::.

. ..

z

. . . 0... IC . . ,

_. 0 _ : _

. _.. - , -.. - .. .0 : ~ , :

: : . . -.. -... 0:. : : .0' - . ~ . : .

0 _ . : 0, , 0 : - ,

z

I 1 D E. PT H B EL OW THE. LEVE.LLED SURFi\CE OF TH E MAXIMUMPOSSIDlE F'ILL IN TH E BIN

4. GENERAL4.1 Location - Location of bins an d special ly those s toring foodgrainsshall conf orm to th e relevant provisions of IS : 5 03 (Pa r t 1)-1969-.Depending upon mater ia l handl ing an d pressure requirements, bins shouldbe suitably located

4.2 Economic Considera tion - Optimum dimensions, shape an d layout, etc, of b ins shal l be selected in accordance with clauses 4.2.1 to .2.3.In addItion the material handl ing Iacili ties shall also be considered.

4 2 1 Dimensions - Volume of each bin an d height to d iameter rat ioshal l be governed by th e storage an d functional requirement of materials.To achieve reduction I I I lateral pressure over a longer height it may bepreferable to select a height d iameter ra tio g reater than or equal to two.

4 2 2 Shape - A bin ma y be circular or polygonal in plan an d isprovided WIth a roof an d a bottom which ma y be fiat, con ical or pyramidal, In case of gravity flow bin, th e angle made by th e hopper With th e

honzontal shall p re fe rably be determined in acc ordance wuh IS : 9178( Part I II to

Ge ne ra l r eq ui re me nt s for srlos for grain storage: Part I Constructionalrequirements.

tCtiteri a for th e deSIgn of steel bin. far storage of bu lk materra s, P ar t I f( B,nsde .jgned for mass How an d funnel How u n d ~preparalwn

1

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IS I 9178 Part I ) - 1979

4 2 3 yout - S torage bins may be e ither free s tanding indiv idua l binsor arranged in th e form of batteries of free standing bins or hms int erconnected in one or both th e direcuons,

5. DESIGN PARAMETERS

5.1 Design parameters of stored materials include bulk density w angle ofinternal fricnon p angle of wall friction 8 an d pressure ratio 11 which areth e governing factors for the computa tion of bin loads Storage and flowcharacteristics of granular materials differ widely from those of powderymaterials.

5.2 Shape of th e Bin - The cross-sectional shape of the bi n is taken intoaccount by the factor R In th e case of intersnce bIOS the value of R shallbe approximated by th e value of R for an equiva lent square bi n of thesame area.

5.3 B ul k D en si ty and Angle o f Internal Fl ic tion - Tables 1 an d2 give the classification and characte ri st ics of bulk mater ia l commonlystored.

TABLE I CLASSIFJCATION OF BULK MATERIALS

M AT F U I A L CHARAf TER1ST1C CL SS

f Very fine 1

rnc sh a nd u nd er Fine 3 mm and unde r BSize Granular 12 mm an d under C

I Lu rnpy-conrammg lumps o ver 12 mm Dl Irregular being fibrous, stringy or th e like H Very free Howmg I

Flowabihty Free flowing 2l Sluggrsh 3r N on-abra ve 6

Abrasiveness Mildly abrasive L Very abrasive 8r Conrarnmable affectmg use or saleability KI Hvgroscoprc LHighly corrosive NI Mildly corrosive PI Gives off dust or fumes harmful to bf e ROther Cbaractefls- Contains explosive dust S

tICS I Degradrable affectmg use of salcabrlrt y TI Very llght an d fluffy WI Interlock. or mats to resrst dIggIng XI Aerates an d fluid rzed YL Packs under pressure Z

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IS I 9178 Par t I ) .1979

TABLE 2 CHARACTERISTICS OF BULK MATERIALS

Claus 5.3 }

D26P 35

D26PT 22-31

C I' 29tS'

D371 i5 '

B ~ Y 10-t'i '

DoB r x 2 7 - ~

; ,1,,

25 > 7

lltWlled]

h T I l t I A L

1

Ammonium chloride, crystallme

Amrnomum nitrate

Amrnomum sulphate

Ashes, coal, dry, 12 m m and un der

Ashes, c oa l , d n 73 mr n and underAshes, coa i, wet, 12 m an d under

Ashe '. coa l , wet, 75 mrn an d under

Aspbalt, crushed, 12 rnm an d under

Bcnzrnc hexachloride

BIcarbonate ck, pellelozed

C dr bo n hl.rck powder

Clndf n , b \lt furnace

Elindcrs, O l I

Coal, anthrac,te

Coal, pi.Ivcrrzod

Coal, powdered

Coal, bituminous, mined, run ofm i n e

Coal, bitllm1nous, mined. sized

Co lnturrunous , maned, slack12 rnrn a nd u nd er

oal br t urrunoua, strippmg, no tcll ' .ned

Coal char

Cuke loovc

Cuke brcez cCr-mcnt

9

AVE1lKG EBULll:.

DE NSIT Y

(2)

kg/rn 3

8307201 000

720-920

56 )640

5606407 BOO

720BOO

no890650

I 120-1 O

320-400

600900

910

640

830-960

510560

800960

80 0

900910

640-800

800

180360-) 10

100-:;(,0

I 0

I l jo

CLASS

(3)

B26LPB27NLS

n2fiNC37

03 7

C27P;;037PZ.

C26

A36R

A26

D27

lll6TZ

A17WZD ~ B

D2B

C:,7P

A N G LE 01 '

I N TERN A L

FRICTION Mm

(4)

Degree

304,'2,

324,'40

38 '

,2 '50

3 1-15

453D

30452821'

35-i5

35-453045

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IS: 9178 Part I ) 1979

TABLE :I CHARACTERISTICS OF RULK MATl:RtALS - Collld

M TI RI L AVER CLASS ANGLE O FBULK INTI;RNAL

D TY F R l f T I O NW M,n

I (2) (3) oJ

kglm S Degree

Copper sulphate. ground I 200 D26P 30D,calclUm phosphate 680 A36 45

V lOdlUm phosphate lOO-490 B27PT 3D oJ5Ferrous sulphate 8001 120 C27 3045

Flue dus t , bai lo r house, dr y 560-720 AHlY C; 30fl y ash, pulverized 560-720Gypsum, calcrned, 12 mm and under 880-960 C27 40Gypsum, calcined, powdered 960-1 280 A37 45Gypmm, raw, > m m and u nd er I 440-1 600 D27 3045Ltms , ground, 3 mm and under 960 B36LZ 45I l in e, hydra led, 3 mm an d u nd er 640 D26Yl 3045

Lirne, hydrated, pulverrzed 510-640 A2lNZ 30-15L,me pebble 840890 D3 6 1.,me.lone, agricultural 3 mm an d I 080 827 301-5

unde r

Limestone, crushed I 360-1 140 D27 301-5Limestone OL : l 880-] 520 A37YL 38.45

Phosphate, ruck, pulverized 960 4052Phosphate rock 1 200-1 360 02 7 30_45Phosphate sand 1 140 1 600 828 3015Potassium carbonate 810 B27L 30-45Potassnun chlorrde, pellets I 9202 OBO C27P 3045Potassrum rutrate 1210 CI7PL C; 3D

Potassium sulphate 610760 B371:

PYrite., pellets 1 g20 2 080 C27R 30-45

h connnun , dry course 640-1 020 271 I 3 45

1h , common dr v fine1 120 I 280

[l27PL 304. >LIt cake, d n I coarse I 3liO 02 7 30

~ t cake, dry, pulvenzcd I HO I 360 B27 35~ . l I l JlJan , U ~ l l l I VD 080 B31l 45

L, n/tolled )

1

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IS 19178 ( Part I ).1979

TABl.E 2 CHARACTERISTICS OF BULK MATERIALS - onld

37

3030-3530- 1-5

35

3724

30-4532

30-453Q-4-S

30-45

23-2621

28293ll

. \> lO LI o .1 f n N ~ LF I U C T N

Attn(4)

Degree

3

GNLS

828BI8D28B27

A27WBt7NSC2bSD265

B26SY

827B27NRZCt1NXL

B17LPS

7a 8W

A EIUOEI lULK

D E N S I T YIV

(2)kg/m 3

1 4401 760I 4401 600

150880-1 040

180-6101 120-1 280

800-960

8801 360

800960960

800880650

750-850t 000

900960820

no 9 Q

M AT E R I A L

Sand, bank, dr y

Sand, i l l ~ l ldr y

Si lica gel

Soda. ash, heavy

Soda, ash, lightSodsum n i tr a te g ranu lar

Sulphur crushed, 12 m m and un derSulphur, 76 mm and underSulphur, powdered

TruodJUm phosphate

Trlple superphosphate

Urea, prills

Ammonntm ni tra te , p ri l ls

CalCIUm arnmomum n ftrate

Deammornum phosphate

Nurophospha te supha la )

Double salt ammonlllm sulphatenltrate)

Single superphosphate {S s. P. },granulated

~ y 27Wheat 850 28Rice 900 33Paddy 575 36Maize 800 30Corn 800 27Sugar 820 35Wheat lIour 700 30

NOTE - T he v alu e. given rn this table may not be taken to be apphcableunIVersally Th e bulk denSlly an d angle of mrernal ffle/wn depend On manyvarrable f acto rs , su ch as morsture content, particle SIZ S , tcrn pe r atur e, cons.olIdatlngpressure, etc Detail s tu dy a nd l es t shaf l be conducted On a ct ua l s ar rp le 10 obi amtheir values under th e ac tua l cond iuon of storage. A reference 10 IS : 9178 Part I l l ) Cr, teroa for Ihe design of steel bIDS fo r storage of Lulk marer ials; Part II I BIDSdesigned for mass flow an d funnel flow under preparation may be made or detaIls.

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IS , 9178 ( Part I . 1 t79

5.4 WaU Fri t: tio ll - In th e absence of rel iable experimental data, theangle of wall f rict ion for granular and powdery materials, irrcspecuve ofth e roughness of bin wall, may be taken as given in T able 3.

TABLE J ANGLE OF WALL FRICTION AN D PRESSURE RATIO

S L MATV,llIAL ANOLE Ol WAI. I . FUICT lON Pnzsstrnn R T I O .No. , - - - - - _ . . . . . . . . _ ~ . ...A.

While While While Whilefilling ernptymg filling ernptying

i1 Granular materia b with o 75 i 06if> o 5 1 0mean parucfe diameter J 0 2 mm

ii) Powdery mal . a , (er- 1-0 t 1 1> 0 . 0 7eept wheal flour 1 Withmean parucle diarnete rI s than 006 mm

Ii, Wheat 11 ur 75 075if> 0 5 0-7

N O T E - F or m at e r la b h av in g m ea n p ar ti cl e drarnerers in between 0 06 mm an d0 2 mm. th e necessary value. r angle of w al l f rr cu on ma y be obtained by linearmterpolanon

5.4.1 there is a possibili ty t ha t t he moisture, Prtssure increase du e toconsolidation, etc, may affect th e an gl e of internal friction an d wallIrrction S then these values shall preferably be determined experimentally.

6. ASSESSMENT OF BIN LOADS

6.1 Gelleral - There a re t hr ee types of loads caused by a stored materialin a bi n s tructure ( Fig. 2 ) :

a) Horizontal load du e to horizontal pressure P b acting on theside walls.

b) Vertical load du e to ve rti ca l p ressure P v) acting on the crosssectional area of th e b in filling.

c) Frict ion wa ll load du e to frictional wall pressure p . introducedinto th e side walls du e to wall friction.

6.1.1Fo r th e

purposeof computing bi n

loadsth e

pressureratio

ofhorizontal to vertical pressure ma y be assumed as given I n Table 3.

6.1.2 In this standard, Janssen s theory ha s been used for th e assessment of bin loads an d th e values of \, an d Ware assumed to be constantalong th e bin height. The theory has been suitably modified wherevernecessary and with this th e structural adequacy an d safety ar e ensured.

J2

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IS 9178 ar t 4 19

h

F lo B IN LOADS

6 ] 3 M a n Flow and unnel Flow ins - Bins ma y be designed on thebasis of mass/funnel flow characierisucs of th e s to red mater ia l to ensurefree flow of material during emptying. Methods of d esig nin g mass flowan d funnel flow bins ar e grven m IS : 9178 ( Part )*.

6 ] 4 Loadmg Condiuons for esign - In general t he loading cases asindicated in Table 4 will give th e govern ing design pressures for the most

adverse loading conditions. However these conditions may be affec ted byarching, plpmg an d SImIlar load increasing phenomena, an d the remedmlmeasures may be adopted to overcome them.

TABLE f GOVElUIJING LOADING CONDITIONS

GRANULAR MAT l n l ALr ~ ~ _ ~ ~

Finite D ep th Infinrte Depth

FIJliIlg FillIng

Ernptymg Empty IIlg

POWflEI tY 1L , T E I l IAr.r ~ . A . . . ~ ~ ~

FIIl. e Depth Intinite Depth

LOADS

Pw Emplying FIllIng Ernptvmg

FIllIng

Emptying

Emptying

FIlling

FIlling mprvrng

Filling

Emptying

6 2 Bin Loads u e to GraDular Materials

6 2 Normal Filling and mPIJ ITlg

C r l l N ~f. , e gnedfor mass [low an d f, \ c1 n w under Jrf{xlrallnn

]

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IS : 9178 Part I I 1979

W

WR

Dunng EmptyiTlg

W

WR

During FIUmg

Maximum Ph

6.2.1.1 AJaxlmum prusures - Th e maximum value-, of the horizontalpressures on the wall P b t he v et ll ca l pressure on th e hOI izontal crosssection of the stored material P y ) an d the vertical load tr ansf err ed tothe wall per unit area due to friction w shall be calculated as follows sre a/so Fig 2 .

Nam of Pressure

Maximum r;

Maximum P v

WR WRPOt ii pe Ae6.2.1.2 P; and P w cannot be maximum at the same time Hence for

the design of hopper bot tom, maximum P y during Iilhng should beconsidered and this value will be the maximum P v at the particular depthmultiplied by area of cross-section of bin. Th e maximum Vi emptyingshall be calculated when the side walls are to be designed at a particulardepth as.

f r; = 1T W [ Z - Zoe 1 - e Zo: Jo

I f hi ratio is less than or equal to 2, the values shall be:a the total weight of stored material when hopper bottom is to be

designed, andb th e value indicated as p . When side walls are to be designed.

6.2.1.3 Variation o f pressure along the depth - Th e variation of p P ban d P y along th e depth of th e bin may be obtained from the expressiongiven below Fig. 3 :

PI Z PIlnw; 1 - - Z I Z o where P stands for pressure an d suffix i stands for w, h or v corres

ponding to the pressure p . Ph or v respectively an d . 0 assumes thevalues given below:

During filling, Zor = p r ArDUrIng emptying, f l Rlp e

Appendix A gives the values of I - e-ZP o for different values of /

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I 9178 ( a r t ) .1 t79

_=--------- P,

z

d

2 d OR

:075hIWHICH EVER ISLESS

EMPTYING__ - ~ R S S U R

FILLING ? ,P , \PRESSURE \PI \ \

lEDUCTION ~T N OTTOM

FIG 3 PRESSURE VARIATION ALONG B IN D EP TH

6.3 Bi n Loads Du e to Powdery Materials

6 3 Normal dllllf] and Emptymg - Maximum design pressures u 1derthis case shal l be computed as specif ied under 6.2. Appropriate values ofv a r IO U S design parameters shall be taken r o Tables :l an d 3.

6 3 2 omogem iation - In the case 01 hornogeruzrng bill, t l H ~fillingconsists of po dery mate ria ls which is circulare d by compressed ai r formixing purposes. During homogenization of powdery rnatenals tho lateral

and vertical pre,sures depend upon the volume of the empty bpace available in the upper portion of the b in . This may be kept about 40 percentof th e total volume of th e bin. Th e lateral an d ver tica l pressures shall beca lculated usmg th e following e x r r s ~ l nan d should not bc h ~ thanp l e ~ s u r eevaluated as in 6.2 .1 :

Ph = Pv = 06 WZ

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IS *9 8 Part t 19 9

6 :4 Rapid Filling - D ur in g r ap id filling-material being filled at arate higher than the minimum fillmg speed-up to a certain height

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IS I 9178 Part I ) 1979

I - - - - \ - - P h NORMAL FILLINGI

rPa

w

0 67P aw

PRESSURE SCHEME FO R P NE UM AT I C EM PTY IN GIG 4

TABLE 5 LOADS IN FERMENTATION BINS

i l us 6 4 )C r > A ~1

S I L m A L R E A D Y

V m t y O ILY

; L A S . 2

DIl Y S I L A O R

Cr ARS 3W E T S lL \OF

Dr y rna in percentage byweIght for fresh silage

Cntical weight of storedmaterta l I n kg/m 3

in kgf/m 3

Pv III kgf/m 3

p in kgffm 3

> 35

5 W

o 7 W Z z

16 Ph

23-35

0 75 W

7 WZ

14 Ph

< 21

1 HI

W Z

vrz 1 Ph

6.5 Hopper Slope - To facilitate asy an d continuous flow It IS essentialt ha t t he slope of th e hopper IS as steep as possible. In th e case of gravityflow, it is recommended that th e angle made by the hopper wall WIth th ehorizontal (valley angle i n th e case of squale an d recrangular hopperbottoms), shall preferably be 15 m ot e t ha n the angle of mternal IJILl IOnof the materia Howe ver t he slope should not Le less than 60 0 tohonzontal.

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IS .9178 Part I 1979

6.5.1 A nomograph to determine t he hopper slope (valley angle inthe case of rectangular an d square hoppers, when the slope of the side wallsare known, is given in Fig. 5.

30

25

A C B 90so BO 90

7080

0

cliQ

/

5/

0

0

amplt:To find vallev angle when A 46 , B = 67 , pl ac t s tra ight -edge so as to cUI

46 on A-Scale a nd 6 7 on B-Seale. Read off answer alley Angle = 43 4 On C-Seale

N O TE - TIllS chart rs based on tho formula t ~ = Cu l 2 C ot 2B

lO 5 N O M OG RAPH FO R VALLEY ANGLES OF HOPI ERS AND Cnurzs

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IS: 9178 PaJ t I 1979

6.6 Effects Causing Increase in Bin Loads

6 6 1 Arching o j Stored Mataial - Some s tored material s ar e susceptibleto arching action across th e bi n walls, Frequent - o I L t p ~of such archesgive rise to increased vertical pressures. The vr r uc.rl pressure on th ebottom of the bin storing s uc h mat er ia ls shall be assumed as twice th epressure. P v calculated as pe r 6.2.1.1 an d 6.2.1.2 subject to a maximumof IV However, this Increased pressure need not be considered w he n t hebi n IS so designed to ehrrnnate arching.

6 6 2 Eccentric Emptymg - Eccentric emptying of a bU gIVes rise toincreased horizontal loads, non-umforrnly distributed \ er th e pcrrpheryan d extending oyer th e full height of th e bin. Eccentric outlets in binsshall be avoided .JS fa r as possible, and, where thev have to be providedto meet funct ional requirements , du e considerauon shall be given in designto th e inci eased pressure experienced by th e walls, Unless determined byinvestigation th e increased pressure may be calculated as glwn 10 6.6.2.1.This increased pressure shall be considered, for th e p pose of design, tobe acting both th e wall nearer to th e outlet as e l l as on th e wall onth e opposite side.

6.6.2.1 The additional pressure Ph shall be considered to ac t for th eIul] height of th e bm an d IS obtained from th e fullowl/lg formula:

Ph = Phi - Ph

where

1 1.1 = Pressure obtained oil th e wal l of th e Inn Imagllled to heenlarged plan so as to make th e eccentric openingconcentric, an d

\ Horizontal r ~ s u ron t he wal l due to stort-d material .

PI, an d 1 / shall he obtamed n conformity with 6.2.1.

6.6.2.2 The enlarged shape of th e bin Inch IS required for th epurpose of computation of the pressure Pl l shall be obtained as shown HIr lg 6.

6.6.2.3 The eIre ct of eccentric outlets may be ignol cd 10 design ifth e ccccntricuy less than d or th e height th e Lw S not grea te r than2 d

6 6 3 Aerauou of um d ateual - When Lms 41 C provided wuh elJUlprnent for \ cnnl.itmg th e bill hlling at rest, a disuncuun shall be madebetween bins for granular material and Inns for powdery material.

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IS s 9178 rt t 1 .,9

,Ph

t ~

, h

t t ttttttt

6A Rectangular Bin

L IACTUAL BIN

ECCENTRIC OUT T

E N L A R G E D lIN

6B Circular Bi n

FI G G uc r or El>Jl 1 YING T UR OL G H E E NT R I O U T L E T S

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IS: 9178 ( Part I ) 1979

6.6.3.1 W he n t he m at er ia l is granular an increase I II LllI ho r izontalpressure to be expected, T he re fo re , t he h or iz on ta l prl : mrt> h ascalculated from 6.2.1.1, for filling is to be increased by the mlct [Jle,;,ureof th e ai r over the portion of th e height of the bi n 1Il which the ai r inletsare located. From th e level of the highest inlet upwards, tlus mcreasein prl ssure ma y be tap ered off unilorrnly down III { l l .rt i he lO pof th e bin.

6.6.3.2 Fo r powdery mater ia ls the investigations made so far do notindicate an y significant increases in load when vennlating.

6.6.3.3 Bins for storage of powdery materials ar e often equipped , ithdevices for pneumatic emptying an d these bring about a looscrnnu of thebi n f il ling in th e region of th e outlet. In this case also, no Ilgl1lfictmtincreases in load due to th e a ir supply have so fa r been detected

6.7 Effects Causing Decrease in th e Bi n Loads

6.7.J m Bottom - In view of the load reducing e{frc t oj the binbot tom, the horrzontal pressure during emptyrna m ay 1 , rr-rhu I'd lip to aheight 1'2 d or 0'75 h whichever IS smaller from the Lm hott om. 'Lhisma y be considered as varying linearly from the ernptvuur piev-ure at dmheight to th e filling pressure at th e bi n bottom see also FIg. 31 .

6 7 2 Special UnioadlTlg Deuces - I f a bm fitted wu lr , I I unlo.iduu;device which allows only th e topmost rnarerr. il ,it , lny tllne I/) I , , thdrawn ( wlule th e layers below I emain at rest) there IS ] n: t d to rakeinto account the excess pressure dunng emptying.

7. FLOW CORRECTING DEVICES

7.1 Flow correcting devices a re p ro vi de d to ensure fl ee a r d milt I l lUOUSflow and to reduce o r e hm in at e t he excess pressure dunng emptyillg

7. 2 Insert type of flow correcting devjr-e is usually used I exrstmz installations with hoppe rs from which funnel Bow takes place i1nd \, b u h nr eds t obe converted into a mass flow hopper or to r educe tcudr nrv to lurm st.iblearches pipes. Flow-correcnve inserts help to increase the hve S(o)',I[(ecapacity an d to reduce segregation problems il l hms hav l ~ht> , )(',,, wrthfunnel flow.

7.2.1 Insert type of flow correctlO { device ma y be used to cor rr t t otypes of flow problems A la rge inser t IS placed see Fu; 7 , \ ; nt'ar th etransition b et we en t he b in and hopper to cause mass flow I I I tf l \ eru: .rlbi n posit ion, A small insert is placed s u FIg 7 B) n ca r the hUPI'CI outletto ehminate plplllg ( rat-hohng ) an d arching of bulk sohds

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IS 9 78 rt I . 979

~ ~ ~

7A 78

FIG 7 TYPIC AL DETAILS OF INSERTS TO F L OW C O RR E CT IO NAN D EMPTYING LOAD

7. 2. 2 The influence of th e msert on th e flow of materials and on th estructural stabiluy of the bin wall should be considered while designin,,: th ebills. The performance of the inserts and their influence on t he m at er ia lflow depend on th e stored material an d th e geometry ol th e bill an dh opp er a nd sh ould be experrrnentally investigated. The support of th einsert should not obs truc t the flow bu t at th e same t ime s ho ul d no t failunder the loads t ha t a re a pp li ed to it. As a gUIde th e diameter S of th eInsert bottom shall no t be less than three times th e annular width sFi g 8 .

7:Z.3 The material remauung in the bm for a period of t im e m ay resultin the forrnauon of arches in th e region of Insert, and may require to be

vibrated to lllltiale th e flow The mser; should, therefore be so design-ed as 10 ensure all round flow.

7 3 Poking devices may be Incorporated III the bins for ensur ing prope rflow Poking may be manual pneumatic With steam or using an y suitablemechanical means like vibrators

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IS 19178 ( Par t ).1919

.I . -- 1 : . \ ~ - -0 1 . 1 . . , n ... . : .. c .. .f ; I ~ I ,..... ~ : ~

: -.... ..~ . , ... , .~ ~ , . _ II, . j ~ ..... -.- : .. .\ 1 4 . \ , -: ~ ... -:, .. . - .. I . . . f

06 t . - . IIl , . . . . . . ~ \ . . / , . . , . . - ... . .

INSEf?1

< :; \ j-- , . .-: (

: . ; { ~..-

t ~s lF l O , 8 SKETCH SHOW1NO INFLUENCr: OF INSE.RT ON TH E

FLOW OF M AT E R IA L

B. MATERIAL HANDLING SYSTEM

8.1 Since the material handling system has an effect on the design of binssome details ar e given for information in Appendix B.

A P P E N D I X A( lause 6.2.1.3 )

VALUES OF L . - Z ) Z o )

{J{a l _ ~ Z Zu ZIZo \_ ZIZ o ZI ::o l - o- ZI ::o Z Zo l-.-ZIZo - - - - -

00 1 0 010 0-56 429 I-II o t>70 1-66 0811o O ~ J 020 [J 57 0435 1 12 0 6 H I 67 0812o s 0030 05 l l o ~ O 1 13 olin 1 68 o 314o IH I) 0,1) 05 9 o 446 11 1 0680 JW 0815o U5 o O J j 0 60 0451 l i S 0 683 J 70 o 817

( Can/ aud- - - - - - - - - -

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IS : 9178 ( a r t I ) 1979

Z Zo J ~ I { o IZ o I e { I { o IZo l e ZJ Z o ZJZo L ZI Z o- - - - - - ~ - - - - -- -

o O,i II O ill 06 \ 0457 ]-16 0687 I-7I 0819007 o III,H I) 1,2 04(,2 I 17 0 690 17 2 0821II (lfj II on 0 6 3 04'67 I If 069 ') I 73 0'623o 0'1 n IIBI; n 64- 0473 I 19 0.;96 \'74- 0824-II \0 o 0'1; n ( 0478 I 20 0699 1 75 0'826o I I o 111+ n 116 II 4R3 ] 21 0'702 1 76 0828II 12 n II J u 67 04-88 1 22 o 7U5 17 7 0830I) 1 \ o I U 0(,8 o 4Y3 I 23 0'708 I 78 0'831II 11 o II I \l 6'1 0498 124- o 7 II I 79 0833II \ o 1 ;'1 070 0503 I 25 071:J I 80 0835

II III II 141l li 71 0508 I 26 o 716 I 81 0836II 17 n I Ii 1)72 0512 \ 27 0'720 \ 82 0838II IH II H,5 ()71 0518 1 28 0'722 I 83 0'840II IOj o I I I IJ 7 0141 I 90 0850l ~ o :llJ o HI II [,55 I 36 f) 7 B I 91 0852o ~ 7 0217 I) 112 o 5GO \ 37 0716 J 92 0853 I 2:; (1211 \) a3 o ~ 4 I 38 a 71B I 93 0855O. . I U J 2 \)IH 0568 I 39 o 751 I 91 0856(J )11 n .. ,q \) as U 573 I 10 n 7 ~ 3 1 95 0057II )] II }iJ 7 II HI; 0577 I 41 0756 19 6 0059o I ~ s l o 117 0501 I 42 0-758 1 97 0061o II II 2,: I II Hl i o ',8J 1 13 0761 1 93 o C62o i f (I 2illl 0 [19 n 50'1 144- 0763 I 'l9 0-8b3n .;- , u 2LI5 () '10 U 5 3 I 45 0765 20 0 a 1165() '1(, u i n l l I ' I l 0597 ]-46 0768 2 05 0871o 'J7 II \11 1 n9 2 U601 14 7 0-770 2 10 0873n m \I li b 093 0605 I 48 0772 2 15 0883o I') \I le3 09 4 0609 I 49 0775 22 0 0889o 411 o I'm 09 5 0'613 1 50 0777 22 5 0895n 1 \ II 1 II, 09 6 0617 I 51 0'779 2 3D 0900o 4 ~ (1113 097 0621 I 52 0-701 235 o 9iJ5UL (I 14 1 n 98 0625 I-53 a 7114 24 0 0909n H (J . J ~ , 6 0-99 o (,21\ 1'54 ()786 2 45 0-914- 4 1 ) 0 % 2 1 OU 0632 1 55 () 708 2 50 0918U 41, ,) ~ ; l n I 01 0616 I 56 o 7 ~ o 255 0922II 17 o \75 I 02 O(dY I 57 IJ 792 2 1,U 0921>n fH 0.181 1 03 06+3 I 5ll 0794- 2 s s 0929

o 1 1 () 3U7 I 01 o 6-1-6 I 59IJ

7 iJ 2 70 0933() ; II ~ J l l 1 05 06.511 1 eo o 7 lB 275 0936II .JI o 41H 1 Ol, 0653 J 61 0800 230 0939(I 52 \I j.(IJ 1 117 0657 1m u ~ . O 2 285 0941o J I o II I I (Ill () t,(() I 63 OWI1 2 90 094-5 '; f (I 117 I 05 a /lO8 30 0 0950

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I s : 9178 Part I .1979

P P E N I X

l use 8

MATERIAL HANDLING SYSTEM

B-1. Th e purpose of providing material handling f ilities in bins is tomake th e necessary arrangement for filling and emptymg the material .This ha s influence in both layout an d design of bunkers in that the loading an d unlo ding arrangements h ve to be considered in the design.

The main equiprnents used for filling/emptying the bins are:a Belt onveyorb Bucket elevator

c Screw conveyord Pneumatic elevator pumping

B.2. Many of th e equipment mentioned above require to be supportedover the bunker wah a suitable openmg on th e cover of the bunker. Th eadditional load thus transmitted to the bunker or Its support ing beamsshould be considered for design.

B3 . Bms should be provided with bunker columns for proper d ischarg ingof th e materials. Th e arrangement ma y include the SImple devices hkecast iron box with slidmg doors operated by hand by bell-crank levers orby power or rot ary valves or discharge gates Or by p ne umat ic methods.The load of th e column an d th e arrangement of ItS connection should beconsidered while designing bunkers and their supporting frame.

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