IS :11855- 1986

Indian Standard

GENERAL REQUIREMENTS FOR RUBBER SEALS FOR HYDRAULIC GATES

Hydraulic Gates and Valves Sectional Committee, BDC 56

Chairman SHRI ~.AD~NARAYANA SASTRI

8A/104 W.E.A., Karol Bagh New Delhi

‘Members Representing

SHRI D. S. AHUJA Nangal Workshops, Irrigation Department, Government of Punjab, Nangal Township

SHRI BALWANT SINGH ( Alternate ) SHRI G. S. ANNIGERI Tungbhadra Steel Products Ltd, P. 0.

Tungbhadra Dam SHRI DHARMINDER CHARAN Irrigat~c;~o;partment ( Government of U. P. ),

CHIEF ENGINEER Irrigation Works ( Government of Punjab ), Chandigarh

DIRECTOR ( M & E ) ( AIternate ) SHRI R. C. CHOPRA TEXMACO Ltd, CaIcutta

SHRI R. BHATTACHARYA ( Alternate ) SHRI H. C. DHINGRA Haryana State Minor Irrigation ( Tubewells )

Corporation Ltd, Chandigarh

SHRI R. S. CHAUHAN ( AIternate ) DIRECTOR Central Water & Power Research Station, Pune

SHRI A. ‘V. GOPALAKRISHNA ( Alternate ) DIRECTOR ( GATES & DESIGNS I ) Central Water Commission, New Delhi

SHRI C. L. VERMA ( Alternate ) SHRI K. K. JULKA Beas Project, Talwara BBMB, Chandigarh

SHRI V. P. KAUSHAL ( Alternate ) SHRI K. V. S. MURTHY Triveni Structurals Ltd, Naini

SHRI M. K. V. SARMA ( Alternate ) SHRI RAI KUMAR Bharat Heavy Electricals Ltd. Hyderabad

SHRI N. Y. NARSIMHAN ( Alternate ) SHRI P. RAMAKRISHNAN Public Works Department ( Government of

Tamilnadu ), Madras SHRI P. ARUNACHALAM ( Alternate )

SHRI S. K. SADHU Jessop & Co Ltd. Calcutta SHRI S. NAG ( Alternate )

( Continued on page 2 )

,@I Copyright 1987 BUREAU OF INDIAN STANDARDS

This publication is protected under the Indian Copyright Act ( XIV of 1957 ) and reproduction in whole or in part by any means except with written permission of the publisher shall be deemed to be an infringement of copyright under the said Act.

Ei : llft55 - 1986

( Continued from page 1 )

Members Representing

SUPERINTENDING ENGINEER CDO, Irrigation and Power Department ( Government NASIK of Maharashtra ), Nasik

SHRI R. SWARUP Central India Mechinery Manufacturing CO Ltd, Bharatpur ( Rajasthan )

SHRI K. C. BEHETY ( Alternate ) SHRI M. C. TEWARI Himachal Pradesh State . Electricity Board

gizrrnment of Himachal Pradesh ),

SHRI N. VISWANATHAN National Hydro-Electric Power Corporation, New Delhi

SHRI G. S. SHARMA ( Alternate ) SHRI G. RAMAN, Director General, BIS ( Ex-officio Member )

Director ( Civ Engg )

Secrefary SHRI HEMANT KUMAR

Deputy Director ( Civ Engg ), BIS

2

r -_- ~~____--..-. ~. 7

IS : 11855,- 1986

Indian Standard

GENERAL, REQUIREMENTS FOR RUBBER SEALS FOR HYDRAULIC GATES

0. FOREWORD

0.1 This Indian Standard was adopted by the Indian Standards Institu- tioa on 30 October 1986, after the draft finalized by the Hydraulic Gates and Valves Sectional Committee had been approved by the Civil Engi- rXeriag;L?ivision Council.

0.2 Dams/barrages are built for storage/diversion of water for irrigation or generation of electric power. In concrete dams, tunnels/spillways, head reguIator of hydel channels, forebay intake structure, by-pass channels and draft tube of power house, the flow of water is controlled with the help of hydraulic gates.

0.3 .To prevent flow of water past a closed gate, seals are provided either on the gate or on the metal frame in the gate slot. Rubber is the most commonly used material for seals, as it is elastic, deforms readily and regains its original shape on removal of load. Reclaimed rubber shall not be used for seals.

1. SCOPE

1.1 This standard lays down the types and requirements for rubber seals used for all common types of hydraulic gates.

2. MATERIALS

2.1 The rubber for seal shall be fabricated from a high-grade, trade-type compound. The basic polymer shall be natural rubber, or a co-polymer of butadene and styrene, or a blend of both. The compound shall contain not less than 70 percent, by volume, of the basic polymer, and the remainder shall consist of reinforcing carbon black, zinc oxide, accele- rators, antioxidents, vulcanizing agents, and plasticizers. The compound shall have the following physical properties:

a) Shore A durometer hardness 65 & 5

b) Minimum elongation 450 percent

c) Ultimate tensile strength 14’5 N/mm2

3

IS:11855 -1986

d) The rubber compound shall not absorb more than 10 percent by mass, of water, in seven days’ test.

e) The tensile strength of the test specimen, after being subjected to an accelerated ageing test of 48 hours in oxygen at 70°C and 2’1 N/mm2 pressure, shall be not less than 80 percent of the strength of the test specimen before agemg.

3. CONSTRUCTION

3.1 Rubber seals may either be moulded or extruded ensuring a homoge- neous cross-section.

3.2 On the hollow bulb seals, a core of rubber stock may be used in the bulb at the splice.

3.3 Corner seals shall be moulded whenever layout permits.

3.4 The metal clad seals shall be held firmly to the rubber through anchors during moulding. The fluorocarbon is introduced into the mould along with the raw-unvulcanized rubber compound and gets moulded and vulcanised simultaneously with the rubber so that the film is inserted or recessed into the rubber.

4. TYPES OF RUBBER SEALS

4.1 The following are the most common types of rubber seals used on gates:

a)

b)

c)

d)

e)

Angle shaped seals

Flat/wedge

Music note seal:

i) solid bulb ii) hollow bulb

Double stem or caisson seal

Double bulb seal

5. USES

5.1 Angle Sbaped Seals - These seals are moulded or extruded to the shape required and the sealing effect is obtained partly due to initial interference with the embeded sealing plate and partly due to the deflec- tion under load. To ensure even tightening of seals and thus to avoid waviness of the seal, brass spacer tubes may be used. This type of seal Ss used on gates on the crests of dams and weirs ( see Fig. 1 ).

4 \

ANGLE SEAL TYPE -I

--._-- ___

IS : 11855 - 1986

l’“t--

eg 7 I_ R1 100

30 --IA 1 -4-t ’ L l,okOI/ LlO

ANGLE SEAL TYPE-II

All dimensions in millimetres.

NOTE - The dimensions of the seals shown in the figure may be taken as indicative and nearest size seals as per moulds available with the manufacturers may also be used.

FIG. 1 COMMON SIZES OF ANGLE SHAPED SEALS

5.2 Flat/Wedge Seals - These seals are used generally as bottom seals for all types of gates and they seal against bottom sealing plate. They require high initial compression loading for proper seating ( see Fig. 2 ).

5.2.1 The projection of bottom wedge seal shall vary from 2 to 5 mm depending upon the requirement and type of installation at the discretion of the designer.

5.3 Music Note Seal - Common sizes and the arrangement of music note seal over the seal base plate are shown in Fig. 3 and 4.

53.1 The initial interference of music note type seal shall vary from 2 to 5 mm depending upon the requirement and typeof its installation at the discretion of the designer.

5

+

---I 2o - I-

‘r 100

,1

r 75

I_ R3 10 -4 li B L

$6 I-

.-q12TOlL~ t_r 6 r_

.1

65

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._R6 TO fj7

All dimensions in millimetres.

NoTE-T~~ dimensions of the seals shown in the figure may be taken as indicative and nearest size seals as per moulds available with the manufacturers may also be used.

[FIG. 2 COMMON SIZES OF FLAT SEALS

$iO,LlO BULB SEAL

qi!!&-: HOLLOW BULB SEAL

Sl No Description J D d t _---

1. Solid and Hollow 57 22 10 8

2. do 100 44 25 14

3. do 125 44 25 14

FOG. 3 COMMON SIZES OF MUSIC NOTE SEALS

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IS : ll@S - 1986

PRESSURE

PRESSURE

COMPRESSION SEALtRECOMMENDED) COMPRESSION SEAL (NOT RECOMMENDED)

LEAKAGE PATH ALONG FLOW (RECOMMENDED)

LEAKAGE PATH PERPENDICULAR TO STEM (NOT RECOMMENDED)

FIG. 4 ARRANGEMENT OF SEALS OVER SEAL BASE PLATE

5.3.2 The music note seal is generally recommended to be used on gates operated for head up to 30 metres.

5.3.3 The hollow bulb music note seal is recommended for gates operated at low head up to 15 metres.

5.3.4 A solid bulb music note seal is recommended for gates operated at medium head, that is at a head of wa:er exceeding 15 m but less than 30 m.

5.4 Double Stem or Caisson Seal - This type of seal is used for heads exceeding 30 m. The sizes are shown in Fig. 5. The sealing will be obtained due to interference of water pressure between the seal seat and seal and also behind the seal in space between the seal base plates.

7

IS :11855 -1986

t

5o1 IL

it

SOLID DOUBLE STEM SEAL

R29-

c HOLLOW DOUBLE STEM SEAL SOLID DOUBLE STEM SEAL

TYPE III

;R22

-70 -

SOLID DOUBLE STEM WITH SOLID DOUBLE STEM WITH BULBS AND ENDS TYPE-I BULBS AT.ENDS TYPE-II

All dimensions in millimetres.

NOTE - The dimensions of seals shown in the figure may be taken as indicative and nearest size seals as per moulds available with the manufactureIs may also be used.

FIG. 5 COMMON SIZES OFDOUBLESTEM SEALS

8

-_.. ..___ --...- - ---. -_~ _ ..__.

IS:11855- 1986

5.4.1 The sealing bulb should rproject 6 mm beyond the face of the clamps. The initial interference of 2 to 5 mm between the plane of the sealing bulb and sealing face of the seal seat is usually provided.

5.4.2 These seals may be used as top, bottom and side seals either by using them with water pressure acting behind them which is withdrawn before the gate is moved to reduce/eliminate friction load or they may be used cladded with metal or fluorocarbon film to achieve the same purpose. On heavy gates such seals may be well used as bottom seals where enough mechanical compression becomes availab!e to make a good seal.

5.5 Double Bulb Seal - These type of seals are used where the gate is required to seal from either upstream or downstream side. These are normally used for installation such as lock gates ( see Fig. 6 >.

6. FORCE ON SEALS DUE TO INTERFERENCE AND DEFLECTION

6.1 An idea of the forces likely to develop in the seal due to compression on account of interference and due to deflection is indicated in the ,curves shown in Fig. 7 and 8 for the guidance of designer.

DOUBLE BULB SEAL

All dimensions in millimetres.

NOTE - The dimensions of seals shown in the figure may be taken as indicative and nearest size seals as per moulds available with the manufacturers may also be used.

FIG. 6 COMMON SIZE OF DOUBLE BULB SEAL

9

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IS : 11855 - 1986

i-

,-

-I 2.5 a

z W--I

r$ 2.c

r,” 00

;: 1.5 _.J- W--. tn

izip n

1-o W

E

if?

0.5

0

70mm SOLID BULB

57mm SOLID BULB

L5mm SOLID BULB

i7mm HOLLOW (Cp 25mm) BULB

;5mm HOLLOW +25mm) BULB

k u PIJ &U 6.0 8.0 10.0

COMPRESSION DUE TO INITIAL

INTERFERENCE

NOTE 1 - The chart will serve as a guide for calculation of approximate loads required to compress the bulb portion of seals in contemplated installations. These values shall be used as an approximation only because of time effect OF ageing and repeated compression cycles of the rubber will influence the results.

d’

NOTE 2 - The information given in the chart is based upon tests.

FIG. 7 FORCES DEVELOPED DUE TO COMPRESSION

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IS :11855- 1986

. LOAD REQUIRED dN A SEAL STEM TO PRODUCE A GIVEN AMOUNT OF

, DEFLECTION(X)

L B-SOLID LINE;lLmm

B-BROKEN LINE -19mm B-DOTTED LINE-25mm

c

DEFLECTION, x IN mm

FIG; 8 FORCES DEVELOPED DUE TO DEFLECTION

7. FRICTION OF SEALS

7.1 The friction of seals shall be in accordance with Appendix F of IS : 5620-1985*.

7.2 The area of loading to determine the frictional load on the seals shall be as under:

a) Caisson Seal - The area ( B X length ) acted upon by water pressure behind the seal ( see Fig. 7 ).

b) Music Note Seal - The projected area ( A X length ) of the seal up to the centre of the bulb ( see Fig. 8 ).

*Recommendations for structural design criteria for design of low head slide gates ( second revision ).

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IS-: 11855 - 1986

3. CLADDED SEALS

8.1 Rubber seals are metal cladded to reduce frictional forces.

8.2 These seals are less flexible than rubber seals. These seals are less ,effective to cover the deficiencies caused by misalignment in the embedded metal of the gate or variations in the gate fabrication. To overcome the drawback of reduced flexibility of fully cladded seals and to cover some degree of misalignment of either the gate or embedded parts, cladding *may be provided on portion of the seal as shown in Fig. 9.

3mm WIDE x 15mm HIGH METAL CLADDING

All dimensions in millimetres.

FIG. 9 TYPICAL EDGE SLOTTING

'8.3 Cladding of seals may be done with brass, bronze, stain!ess steel or fluorocarbon. The fluorocarbon cladded seals have more flexibility and a very low value of friction.

8.4 The normal thickness of cladding in case of cladded seals is 0 to 1’5 mm. For metal cladded seals ( bronze or steel ) and fluorocarbon vary from 0’75 mm to 1’5 mm.

8.5 For metal cladded seals suitable tests shall be carried out such that the seal shall not fail in adhesion between the rubber and the cladding. The test shall ensure adhesion bond of 176 N/cm nidth of the seal for a separation rate of 2’5 cm/minute.

8.6 The test shall ensure adhesion bond between the fluorocarbon and rubber as 54 N/cm width of the seal for a separation rate of 5 cm/ minute.

8.7 The ends of seals to be joined at site shall be cut to square at places- where they butt against the adjacent length. Rubber cementing compound shall be applied at the meeting faces of the seals.

12

‘ZS : 11855 - 19%

9. TRANSPORTATION, HANDLING AND STORAGE OF SEALS

9.1 Adequate care shall be taken for proper packing of seals to avoid damage in transport and storage.

9.2 The seals should not be allowed to come in contact with any sharp edged or pointed objects or any abrasive surface that might cut or tear the rubber.

9.3 Direct sunlight, oxygen and ozone effects the physical properties of rubber and causes to ag: more quickly. Seals, therefore, should be stored in a dark cool room.

(_ 9.4 It is suggested to leave the seals in the original packing lining on a flat surface, however, the seal shall be unrolled and kept, in a straight position on a flat surface at least 48 hours before insialliog it.

13

c . -_-

BNTERNATIONAL SYSTEM OF UNITS ( SI UNITS )

Base Units

Quantity

Length

Mass

Time

Electric current

Thermodynamic temperature

Luminous intensity

Amount of substance

Unit

metre

kilogram

second

ampere

kelvin

Symbol

m

kg

S

A

K

candela

mole

cd

mol

Supplementary Units

Quantity

Plane angle

Solid angle

Derived Units

Quantity

Force

Energy

Power

Flux

Flux density

Frequency

Electric conductance

Electromotive force

Pressure, stress

Unit

radian

steradian

Unit

newton

joule

watt

weber

tesla

hertz

siemens

volt

Pascal

Symbol

rad

sr

Symbol

N

J

W

Wb

T

HZ

S

V

Pa

Definition

1N = 1 kg.m/s*

1J = 1 N.m

1w = 1 J/s

1 Wb = 1 V.S

1T = 1 Wb/m’

1 Hz = 1 c/s(s-1)

1s = 1 A/V

1v = 1 W/A

1 Pa = 1 N/m*