structural design of penstock indian standard

8/12/2019 Structural Design of Penstock Indian Standard

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lS11639 Part3):1996

Indian StandardSTRUCTURAL DESIGN OF PENSTOCK - CRITERIA

PART 3 SPECIALS FOR PENSTOCKS

ICS 23.040; 93.160

( Reaffirmed 2001 )


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Conductor System Sectional Committee, RVD 14

ian Standard ( Part 3 ) was adopted by the Bureau of Indian Standards, after the draft finalizedthe Water Conductor System Sectional Committee had been approved by the River Valley Divisiontypes of specials like bends, reducers, expansion joints, etc are used in steel penstocks carryingsurge tanks or reservoirs to the power houses. This standard covers the structural design aspectsuch specials taking into account the important hydraulic parameters involved, This standard is beinin three parts: Part 1 Surface penstocks, Part 2 Buried / embedded penstock and Part 3 Special

the purpose of deciding whether a particular requirement of this standard is complied with, the finobserved or calculated, expressing the result of a test or analysis, should be rounded off in accordanceIS 2 : 1960 Rules for rounding off numerical values ( revised . The number of significant placein the rounded off value should be the same as that of the specified value in this standard.


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Indian StandardIS 11639 Part 3 ) : 1996

STRUCTU&AL DESIGN OF PENSTOCM - CRITERIAPART 3 SPECIALS FOR PENSTOCKS

( Part 3 ) lays down the criteria fordesign of the following specials used in

a) Bends,b) Keducer pieces,c) Branch pipes,d) Expansion joints and dresser couplings,e) Manholes,f) Bulk heads,g) Air vents and air valves, andh) Other miscellaneous penstock accessories.REFERENCES

following Indian Standards are necessary adjuncts

IS No.: 1969

1625 : 10X611639(Partl):l%6

BENDS

tleCode for -unfixed pressurevesselsCriteria for hydraulic design ofpenstocksCriteria for structural design ofpenstocks: Part 1 Surfacepenstocks

on topography, the aligmnent of the penstockoften required to be changed, in direction, to obtainsr eccnomical profile so as to avoid excess

of foundation strata and also to give it anc look with the surroundings. These changes in

are accomplished by curved sections,omnnouly called penstock bends. For ease of fabrication,the bends are made up of short segments of pipes with

mitretl ends.Bends should be made with large-radius and smalldeflection between successive segments in order tominimize the hydraulic loss due to change in direction

is very important, deflection augles from 4 degrees to 6degrees may be used. From the consideration ofalignment, penstock bends are generally classified assimple bends, compound bends and reducing bends.3.2 Simple BendsWhen the change of alignment is only in one plane, thais either vertical or horizontal, the bend is called a simplebend and the deflection angle is the deviation in thedirection of alignment ( see Fig. IA ).3.3 Compound BendsWhen the change of alignment is in both the planes,that is vertical as well as horizontal, it is advantageousto accommodate the deflections, in both the planes, byproviding a single bend known as a compound bend( see Fig. 1B ) Usually the plan angle and profile anglesare known and it is required to determine the true anglein the plane of the bend and the bend rotations. Someguidance regarding computations and applicableformulae for various situations are given in Annex ADuring the installation of bends in the field the bendisto be rotated by a certain angle which is indicated a13and @ in Annex A.3.4 Reducing BendsIn long and very high head penstocks, it sometimesbecomes necessary to decrease the diameter of the pipas the head increases. In such cases it is advantageous tcombine the reduction in diameter with a bend, wherevepossible. by providing a reducing bend ( see Fig. 1C For the design of reducer bends the following simplifiedformulae may be used:

D,-2(x-l)HtanPSin8D, = (cm 6PA. _.. (in

Sin 8 = D, -D,2 ( n-2 ) R tan Ptan$= Sin 21 :cos 2P + cos I3 (i

rl Sin 0z, =- . . ...(v


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IS 11639 Part 3 ) : 1996r, Sin 0Y, = _. (vii)cos P

PROFILE

PROFILE ANGLE APROFILE ANGLE BPLAN ANGLE CTRUE ANGLE D

1 B Compound BendPOINT OF COMMENCEMENT

whcrc11, =

.r =

R =11, =:z =A =D,, =11 =,-,, :=

1A Simple Bend DetailsFIG. 1 TYPE BEND DETAILS

1 C Reducing Bend

Iuside diameter of pipe at the point underconsiderations in mm,Number of divisions from plane PC topoint under considerations,Radius of bend in mm,Inside diameter of large pipe in mm,Number of deflections,Angle of intersection in degrees,Inside diameter of small pipe in mm,1,,12.r ,/2,

r 1 = r,-(x-l)RtanPSinq,6, = Angle as shown in Fig. 1C in degrees, and@ = Angle as shown in Fig. I(1 in degrees.

4 REDUCER PIECE4.1 GeneralIn the case of very long penstocks, it is often necessaryto reduce the diameter of the pipe as the head on thpipe increases. This reduction from one diameter another should be effected gradually by introducing special pipe piece called reducer piece.4.2 The reducer piece is a frustum of a cone. Normallythe angle of convergence should be kept between5 degrees to 10 degrees soas to minimize the hydraulic


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of reducer pipe may be calculated by the

L==

andD, =

L= D, D*2tangLength of reducer pipe in mm,Angle of convergence in degrees, andDiameter at the entry and exitrespectively in mm.

The thickness of the reducer apiece may beusing the following formula:PDt=

P =D=

a =na =E =

C=

internal water pressure in N/mm*,internal diameter of the reducer at the largerend in mmhalf apex angle,allowable stress in steel in N/mm*,lowest efficiency of any joint ( seeIS 2825 : 1969), andcorrosion allowance ( see IS 2825 : 1969 ).

Generalupon the number of units a single penstockpenstock branching is defined as bifurcationfeeding two units, bifurcation when feeding threeand manifold when feeding a greater number of

by successive bifurcations. Branch pipes oftype are generally known as *wye piecesbe symmetrical or assymetrical.Generally the bifurcating pipe has two symmetricbifurcating joints, and the deflection angle

the branching pipes ranges between 30 degrees to 75In order to reduce the head loss, a smallerangle is~advantageous. However, the lesserbifurcating angle, greater the reinforcement requiredthe bifurcating part. The wye branches should be givencare in design to ensure safety of the assemblyinternal pressure of water. The introduction of aconsiderably alters the structural behaviourf the penstock in the vicinity of the branching.

5.3 The hydraulic requirement requires the inlet andoutlet velocities equal at full load and the branch pipetransition conical, with elliptical section along the plane

IS 11639 ( Part 3 ) : 1996the junction.5.4 One method of reinforcing the branches is to provideexternal girder and stiffener ring with an internal tie-rod ( see Fig. 2 ). The deflections of U girder, ringgirder and tie-rod due to internal pressure are determinedin terms of unknown reaction by strain energy method.Equating these at the point of intersection, unknownreactions are determined and the stresses in thesemembers checked.5.5 Another method of reinforcing the wye is to providea single elliptically shaped sickle plate at the plane ofintersection. Typical bifurcation with sickle typereinforcement is shown in Fig.3. The practice is morecommonly adopted for high head penstock branches. Thesections along the bifurcations consist of two intersectingrings with angle (@) varying longitudinally. The ringsare interconnected longitudinally by the splitter plateto avoid large deformations and consequent high stresses.The splitter plate is designed to take up the unbalancedloads at the intersection. The splitter section is formedalong the intersection plane of the conical branches planeand has the form of an ellipse with semi-major and minoraXeS.The introduction of splitter does not materially alterthe state of stress in the shell, in symmetricalbifurcations, as the thin walled shells do not resistbending, but carry load by membrane action.The design of the sickle reinforcement involves:

a) Determining the shape of the sickle to ensuresufficient radial plate width, to keep theresultant reaction exactly at the centre of widthof any particular place, and thus obviateeccentricity and its effects; and

b) The thickness of the sickle to keep the stresseswithin the permissible limits, that is same asstress in shell.5.6 In the case of unsymmetrical branching, shellstresses are affected to a large extent and additionalreinforcement in the form of ring girder is required atthe start of the bifurcation to minimiz.e deformation andstresses. The analytical approach for design of ring girderis based on strain energy principle. The deformation otthe ring girder determined in terms of the unknownreactions, is equated to that of the splitter plate at thepoint of intersection. The unknown reactions and stressesare obtained for proportioning of ring girder dimensions.The influence of the ring girder dies down approximatelyat a length of 0.3 R where R is the radius of the pipe.5.7 For accurate determination of stress in the shelland reinforcing elements of an unsymmetrical branching,a structural model with strain gauge measurements is


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IS 11639 Part 3 ) : 1996

FIELD WELD

PLAN OF BIFURCATION

DD AA BB CC

FIG.~ DETAILSOF BIFURCATIONYPE WYE PIECEWITHEXTERNALREINFORCEMENI

5.8 The third type of pipe branching is in the form ofa spherical shell enclosing the bifurca.tion point. In thiscase, in order to reduce the .water head loss, resultingfrom the suddenly increased inner volume at thespherical part, flow rectifying plates are provided insidethe spherical shell.5.9 Hydraulic aspects of the head losses for differenttypes of branches are described in IS 11625 : 1986.6 EXPANSION .JOJNTS AND DRESSERCOUPLXNGS6.1 GeneralExpansion joints are installed in exposed penstocksbetween fixed point or anchors to permit longitudinalexpansion, or contraction when changes in temperatureoccur and to permit slight rotation when conduits passthrough two structures where differential settlementor deflection is anticipated. The expansion joints arelocated in between two anchor blocks generallydownstream of uphill anchor block. This facilitates easyerection of pipes on steep slopes.6.2 Expansion joints should have sufficient strengthand water tightness and should be constructed so as tosatisfactorily perform their function against longitudinalexpansion and contraction. The range of variations to

be used for calculation of expanded or contracted lengthof penstocks should be determined keeping inconsideration the maximum and minimum temperatureof the erection sites.6.3 Depending upon the internal pressure, diameter ofpipe and magnitude of movement expected, the followingtypes of expansion joints are used for penstocks:

a) Sleeve type expansion joint, andb) Bellows type expansion joint.

6.3.1 For large diameter fabricated steel pipe, sleevetype expansion joint is generally used. In this type, thelongitudinal movement of the pipe is permitted by theprovision f wo closely fitting sleeves, the outer sleevesliding over the inner sleeve. To prevent leakage, packingrings are provided between the sleeves within a stuffingbox and held by a retainer ring and packing glands withbolts. The outer surface of the inner sleeve is usuallygiven a stainless steel/nickel cladding to preventcorrosion and reduce friction to facilitate easy movementof the joint. The gland bolts press the gland inside thespace between the inner and outer sleeves against thepacking material consisting of lubricated flax which isretained by an inner ring. Typical details ofa sleeve typeexpansion joint are shown in Fig. 4 A.


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IS 11639 ( Part 3 ) : 199DOWN STREAM

tI p11i cI i

III

FIG.~TYPICALBIFURCATION ITH NTERNAL EINFORCEMENTshows a special double sleeve type of expansionThis is more flexible to permit longitudinal asDesign of gl nd bolt

designed to exert enough pressure on the1.25 to 1.5 times the internal hydrostaticmobilised between the sleeves and the packing.Poissons ratio may be taken as 0.3 for flax

PZexerted on it by packing due to

p, Ppz=1-p) . . . 0MA Y,Total bolt force = - s.

where. . . . (x

P = internal pressure in the pipe in N/mm2 andP, = pressure mobilized between packing and


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STUD FULLY THREADED/- INNER SLEEVE / LOOSE RINGFLOW

DGNBOLT CENTRE LINk

IN LEG AT THIS POINT

FORCES ON GLAND

0 RINGFLAX PACKING

4A Single SleeveType

GLAND TO BE HOT DIP GALVANIZED/-- AFTER MACHINING AND DRILLING

I I

A -

LONGITUDINAL SEAM ON BOTHSIDES OF THE GLAND ON INSIDEOF STUFFING BOX I INSIDE OFRETAHER RING TO BEGROUND FLUSH

GRIND SMOOTHAFTER WELDING 7PUSH OFF BOLTS EQUALLYSPACED BETWEEN STUDS C.L OF EXP. JOINTI NICKEL CLAD STEELI INNER SLEEVE

RINGS LUBRICATED 0FLAX PACKING

A A

48 Double Sleeve TypeFIG.4 SLEEVE TYPEEXPANSIONON


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whereM = number of bolts,A. = root area of bolt in /mm,Y, = yield point~of the material in N/mm*,f, = factor of safety,W= diameter to the centre of packing rings inmm,W = width of packing ring in mm, andp = poissons ratio

The spacing of bolt is generally kept at 250 mm to 300mm centre to centre. The packing should consist of 4 to8 rings of square, lubricated, braided long fibre flax rings,the number depending upon the internal pressure. Thesize of the packing may vary from 16 mm to 32 mmdepending upon the size of expansion joint.6.3.1.2 Design of inner sleeveLength of sleeve t L ) should not be less than value givenby the formula: 21F

L=hwhere there is no water inside the penstock, then therewill be only external pressure Pz. The actual hoop stresswill bc less than ( P, R, )lt since it is loaded for shorterlength. It may be taken as

whereL = actual length in mm over which the load is

applied1 = plateconstant =

1.285=JR,t for p = 0.;

R, = D/2, andt = thickness of leg of gland in mm

This uniformly distributed load over short length wouldgive rise to additional axial moment M and axial bendingstress as given below :

These two stresses will be acting simultaneously. Thisbending moment will die out after a certain distanGeand so also the hoop stress. The combined stress u isgiven by:

IS 11639 ( Part 3 ) : 1996A factor of safety of 2 to 3 is normally adopted to arriveat allowable working~stress.6.3.1.3 Design of glwdThe gland flange should be able to resist the bendingmoment developed by the gland bolt forces. The glandshould be designed such that the gland bolts yield beforethe gland.

1.285J. =- rt where r = inside radius of gland in mmF = bolt force per mm of inside circumference

_ MAYO2rrrM, = applied moment per mm of insidecircumference

=F[R- r+t/2)]

A4, = Y1+F+lP @?~log,, ( 1- ;>

=a= bending stress in leg6ia/r,=f- N/mm*t*

0 E = compressive stress in legF= - - N/mm*

Total stress in leg = cr + cr ( should be less than yieldpoint with allowable hctdr of safety ).6.3.2 Bellows_Type Expansion JointBellows type of expansion joints are generally used forlow pressure pipe lines and for pipes of moderatediameters and for slight movements. There is no slidingsurface in this joint and the expansion is obtained bythe flexibility of the thin plates forming the joint. Theflexible diaphragm will either stretch or compress inthe direction of pipe axis to allow for the longitudinalmovement of the pipe. Such tm of joints are not suitablefor high heads above 15 m to 20 m because the thicknessof diaphragm required to withstand the internal pressurewould be too stiff to allow for any flexibility oexpansion, A typical bellows type of joint is shown inFig. 5.

DIRECTION OF FLOW


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IS 11639 ( Part 3 ) : 19966.4 Dresser CoupiingsCouplings are used in the installation of steel pipes ofmoderate diameter, say upto 1.8 m to 2.5 m, for joiningpipe lengths in the field. They are flexible formovement of pipes and allow for about r0 mm movementand 3 degrees to 4 degrees deflection at each joint. Sincethe components are simple, they permit speedyinstallation under different site conditions.Wherever couplings are provided expansion joints areeliminated. They are specially suitable where it isdesireable to eliminate field welding. A typical dressercoupling is shown in Fig. 6.The joint consists of one cylindrical steel middle ring,two follower rings on either side, two resilient gasketsof special compound and a set of high strength steel trackhead bolts. The middle ring has a conical flare at eachend to receive the wedge portion of the gasket and thefollower rings confine to the outer shape of the gaskets.Thebolts are tightened so as to draw the follower ringstogether, thereby compressing the gaskets between themiddle ring and pipe surface, to effect a flexible andleakproof seal.

PLAIN END PIPE -s/

, FOLLOWER

- 4Illi ,&T\ MIDDLE RiNG

FIG.~DRESSEROUPLING

7 MANHOLES7.1 GeneralManholes are provided in the course of the penstocklength to provide access to the pipe interior forinspection, maintenance and repair.7.2 The normal diameter of manholes is 500 mm.Typical details are shown in Fig.7. Manholes arcgenerally located at intervals of 120-150 metres. Forconvenient entrance, exit manholes on the penstock maybc located on the top surface or lower left or right surface~tlong he circumference of the penstock.

7.3 The manhole, in general, consists of a circularnozzle head, or wall, at the opening of the pipe, with acover plate fitted to it by bolts. Sealing gaskets areprovided between nozzle head and cover plate to preventleakage. The nozzle head, cover plates and bolts shouldbe designed to withstand the internal water pressure headin the penstock at the position of the manhole.7.4 The pipe should be reinforced around the manholeby providing extra reinforcing plate adjacent to nozzlehead. Sectional area of reinforcement should be at least5 percent to 10 percent greater than the sectional areaof the pipe shell.8 BULKHEADS8.1 GeneralBulkheads are required for the purpose of hydrostaticpressure testing of individual bends, after fabrication,and sections or whole of steel penstock and expansionjoints, before commissioning. Bulkheads are alsoprovided whenever the penstocks are to be closed fortemporary periods, as in phased construction.8.2 The shapes of the test heads generally adopted arehemispherical, semi-ellipsoidal or standard dished flangeends as shown in Fig. 8.8.3 The test heads and bulkheads should be designed towithstand the test pressure of the pipe set tion8.4 The bulkheads should be fabricated out of the samematerial as used in the penstock.8.5 For the design of shape, size and connection detailsof bulkheads see IS 2825 : 1969.9 AIR VENTS AND AIR VALVES9.1 GeneralThese are provided on the immediate downstream sideof the control gate or valve to facilitate connection withthe atmosphere.Air inlets serve the purpose of admitting air into thepipes when the control gate or valve is closed and thepenstock is drained, thus avoiding collapse of the pipedue to vacuum excessive negative pressure. Similarly,when the penstock is being filled up, these vents allowproper escape of air from the pipes.9.2 The factors governing the size of the vents are length,diameter, thickness, head of water, and discharge in thepenstock and strength of the penstock under externalpressure.9.3 Size of the air vent may be determined by thefollowing formula:


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IS 11639 Part 3 ) : 1996

e L BOLT HOLES

HOT ROLLEDCARBON STEEL

COVER PLATE

GASKET (ASBESTOSSUITABLE BINDER)

REINFORCING PLATEAA

FIG.~MAN HOLEDETAILS

f i STRAIGHT FLANGE --I

KNUCKLE RADIUS 0 t

SEMI-ELLIPSOIDAL STANDARD DISHED

STRAIGHT FLANGEit-

I r MICRO SWITCHROD

VALVE

VALVE

PACKING

T


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IS 11639 Part 3 ) : 1996where

F = arca of air inlet in mz,Q = flow of air through inlet in m3/s,S = factor of safety against collapse of pipe,C = co-efficient of discharge through airvent( generally 0.6 1,n = ~diameter of steel pipe in mm, andf = thickness of steel pipe in mm.

9.4 Air valves are subject to great impact during closingor opening. Therefore, their construction should becapable of withstanding such impact. A typical air valveis shown in Fig. 9.9.5 The minimum sectional area of the air valve maybe determined by the following equation:

whereA =Q =

h =

maximum flow sectional area in m*,maximum water flow in pipe in m3/s,difference between allowance pressurein t/m3,

Ya = air density in t/m3 ( generally 0.001226t/m3 ),

9 = acceleration due to gravity in m/s*, andc = flow co-efficient ( generally 0.6 ).

9.6 In order to avoid risk in the event of failure of r_irvalves, it is desirable to provide two or more redudantair valves, so that minor malfunction of air valve willnot cause serious damage.10 MISCELLANEOUS IENSTOCKACCESSOIUES10.1 Piezometric ConnectionsPiezometric connections aresprovided in the penstockpipes to facilitate connections to pressure gauges locatedin the control room. Normally these piezometricconnections are provided in the straight length ofpenstock away from bends and branches and near thevicinity of the power house. They are provided in groupsof four, equally spaced around the periphery of thepipe section. From each group of these connections thepiezometric line is connected to a pressure gauge.Details of a~typical piezometric connection are shownin Fig. 10.

GRlND END FLUSH WITH IN SIDE OF PENSTOCK

\ ~--p:;,;;~;~.,

i PIPETOP

FIG. 10 REZOMETRICCDNNECTION10.2 Flanged ConnectionsFlanged connections are provided for connecting thepenstock with other equipment like valves, expansionjoints, turbine scroll case, etc. The type and the designof the flanges shall be made to suit the connecting flangesof the equipment to which the penstock is to be connected.Welding neck type, slip on type and plate type flangeconnections are generally adopted. Generally, thwelding neck type is of forged steel and is used for highheads and pipes of large diameter while the other typesare used for medium and low heads and withpipes osmaller diameter. Design of flanged connections shalbe done according to IS 2825 : 1969.10.3 Filling ConnectionsIntake nozzles are provided in the penstock at suitablelocations for connection with tilling lines, in order tallow slow filling of penstock during initial ftlling othe water conductor system. Normally these intaknozzle openings are providedat the horizontal centre opipes, at the upstream end of penstock. It is preferableto provide this comiection on the downstream side othe penstock gate so that filling can be effected undesubmerged conditions. T lrse lilling lines are connectedwith the reservoir on the other end and provided witproper control valves. These lines should be of sufficiencapacity to complete the filling of entire length openstock within a reasonable time. Design of fillinconnection should be done according to IS 2825 : 19610.4 Drainage ConnectionsDrainage connections are required to be provided fdraining of the penstock whenever the penstock is to inspected for maintenance and repairs. Drainage nozzleare located at the bottom most reach of the penstock the lowest point of the pipe with proper grating, fluswith the inner surface of the pipe. The drainage lineare normally comiected to the draft tube of the turbine


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IS 11639 Part 3 ) : 1996

Closing Piecesble errors might occur in the penstock

due to errors in the process of fabrication orat site or due to discrepancies betweencalculations and actual laying of pipe lengthssite, or due to shrinkage of welded joints. In order tothe final field adjustments and to obtain perfect

assembly of the pipe line system a make-up piece ofpipe length called closing piece is often provided. Theseclosing pieces should be fabricated with an extra lengthwhich is cut to size at site, after erection of entirepenstock. Normally, these pipes are fitted either at theconnection to the valves or near expansion joints or nearturbine scroll case. Design of closing pieces should bedone according to IS 11639 ( Part 1) : 1986.

I ANNEX ACl a u se 3.3

TOPMATCHOlNT

DEVELOPED PLAN1 2 -_ -_-^---_

C

\ 3PLAN

COS 0 5 COS A CO5 B COS C + Sin A Sin B

PROFILE Tan A CosbSin a +


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IS 11639 Pait 3 ) : 1996

PROFILES

J ___ K-

----Y

PLAN

DEVELOPED PLAN co5 D = cos 0 cos c

Sill cTan8 =- Tan BTan Cfan - - Sin B

DEVELOPED PLANCosD - cos 0 cos c

Sm CTone -- Tan BTan CTan6 = -gy-

DEVELOPED PLAN

COP D = os A Cos CTanB =_ Tan CSm A

Sm CTan9 = -Tan A

PLAN*e* --.pDEVELOPES PLAN

Cos D = Cos B Cos CStn CTan 8 = ___Tan 0Tan CTan@ =- Sin B

-q

\ -9.DEVELOPED 6LANcos D - cos B cos c

Stn CTan8 - ___Tan 0Tan CTanp = ~Sm B

DEVELQPED PLAN

os D = Cos A Cos CTan CTane =---- Sm ASin CTan+ = ~Tan A


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jS 11639 Part 3 ) : 1996

PLANE OF BENDTOP MATCH POINT

TOP MATCH -POINT----PLANE OF BEND

DEVELOPED PLAN

cos D = Cos A Cos CTan8 = ___

Tan@ = ___

DEVELOPED PLsANCos D = Cos A Cos C

Tan CTan8 =- Stn ASin CTon$ = ~ Tan A

PLANE OF BENDTOP MATCH POIM

TOP MATCH FC4NTPLANE OF BEND

DEVELOPED PLANCos D =CosACasB CosC-tSmASmB Gas D=CosAPosB CosC- -SrnA SmB

Tan B Cos A

TMP = SmA -


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; IS 11639 Part 3 ) -: 1996

k- - BA- -h 3

DEVELOPEhLANCOS 0 : Cos A COS B OS C Sin A Sin B COsD: COrhCosBCosC +SiASmBTon 0 : Tan C la0 z Ton C

Sfn-A - Tan6 COSAcos c

Tan+ 5 To cSlB - TonA CosB

TMP z

DEVELOPED PUN wCos D : Cos A Cos B Cos C c Sin Sin BTan0 : Tan C

SinA- TanB CosAcost

Tan 0 : Tan CSinB- laA CosB

1MP I Sin A-[;i;$$q

Cos D z Cos A Cos B COSC -t SinA Sin BTan0 z Tan C

Sin A - TonB CosATM+ J

Cos cTan cSinB-TanA CosB

cos cTMP = Sin E -c;:;$iA 1 .

Sin A- Tan B CarAcos cTan (I : Tan C

Sin B - Ta A COSBTMP =

PLANE OF BEND

DEVELOPED PLANCosD: CosACosB CorC+SiASiBTon8 I Tan C

stn A- Tan B CosA--COJ c

To jl z Tan C_____.Sln B-TaA Cos 0--TMP = Si A-pz$Bi,

DEVELOPED hANCos D : Cos A Cos B Cos C +SiA Sm 0Tan0 z Tan C

SinA - TanB CosAcos c

Ton $I = Tan CSt B- To ACOS B

cos c7MP = Sin B-/-k;II


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IS 11639 Part 3 ) : 1996

DEVELOPED PLANCo D = co, A Cos B Cor C-Stn A 5.811 B-ran0 E Ton c

StnA+ Tan 8 Cor ACOSC

lank : Tan cSan B + Tan A COS B

DEVELOPED PLANCcrS D: COS A Cos B Co5 C-Sin A SrnB

Tan C-fan0 1 SlnA + Ton B CosA

CL% cTan$?l z Tan c

Sin f3+TanA Co58co5 c

DEVELOPED PLANCOs D=CO~ACOSDCO%C-SI~AS~B

Ton 0 = -ran cSmA+ ion B Cos A

cos cTan @ Ian c -

Stn B+ Tan A Cos B

PLANE OF BENDTOP MATCH POINT

DE VE LOPED PLANCoS 3~ =a5 A Co5 B COS C-S1m-1 A 51n 0

Ton cTon 0 z Srn As Ton B Cos A

cos can $ = Tan cSrn B+Ton A OS B

TMP. L


21/24


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AMENDMENT

IS 11639 PART 3 :1996

NO. 1 MAY 2002TOSTRUCTURAL DESIGN OF

PENSTOCK CRITERIAPART SPECIALS FOR PENSTOCKS

Page 7, clause 6.3.1.2 :a

b

Substitute t= thickness of the inner sleeve in mm~or t= thickness of leggland in mmInsert the following:D = inside diameter of penstock shell or inner sleeve.

Page 7, clause 6.3.1.3 :a Substitute [l for t wherever occuring in the clause and insert

tl = thickness of leg of gland n mmb Substitute:

1.285?L=- ~,~ for ~= rlc Substitute:

for

WRD 14

Reprography Unit BIS New Delhi India


24/24

AMENDMENT NO. 3 DECEMBER 2006

TO

IS 11639 (PART 3) : 1996 STRUCTURAL DESIGN OF PENSTOCK CRITERIA

[Page7, clasue6.3.1.3(see also Amendment No.1)] Substitute:

+

++

=

r

b

t

a

r

a

MM

110log1513.1

21

3

1

t0

for

+

+

+=

r

b

t

a

r

a

MM

110log1513.1

2

13

1

t0

(WRD 14)

Reprography Unit, BIS, New Delhi, India

structural design of penstock indian standard

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