ONE DAY WORKSHOP ON DAM’S GATES ORGANISED BYNARMADA, WATER RESOURCES, WATER SUPPLY & KALPSAR DEPARTMENT GANDHINAGAR SUPPORTED BY WALMI - ANANAD
SUB:-DESIGN ASPECT OF VARIOUS TYPES OF GATAES PAPER BY ER. A.P. PANDEY C.D.O. GANDHINAGAR
Being vital components of dams, gates are installed on spillway to store water and create reservoir behind them. They regulate the release of water for various purposes for which they are planned. The spillway gates regulate and control the flood discharge., Outlet gates control the release water for irrigation, penstock gates release water for power generation.
Basic requirements to be satisfy by the gates are as under: (1) Water tightness (2) Can be operated by hoist at specified speed. (3) Alternative operation device in case of power operated gate. (4) Regulating gate should be held in any partials operation position to pass required discharge without cavitations and undue vibration.
• The unobstructed operation of the flood gates of any water project is of utmost importance.• The choice of the type of gate and its operating mechanism is critical for that reason• For low head flood gates of dams, which are usually quite wide, the conventional choice includes Vertical Lift, Radial, Automatic or Needle type gates.
• The operation And maintenance of each type is unique and each type presents certain advantages and disadvantages.• The primary considerations for the selection of the gate type include gate size requirement, expected flows, efficiency of discharge and initial cost.
There are so many classifications for designating the types of gates. Out of that following three most commonly used.TYPES OF GATES(1) On the bases of design head:(2) On the bases of location and purpose(3) On the basis of their operation and shape.
(1) On the bases of design head: • High head – above 30m • Medium head‐ between 15m to 30m • Low head – less than 15m
2 On the bases of location and purpose 1.Crest gates : » Spillway crest gates and » Barrage crest gates 2. Outlet gates : » By pass outlet gates » H.R. Gates » Penstock intake gates » Sluice gates Construction sluices Scouring sluices Under sluice
3 On the basis of their operation and shape.– Radial gate/ Taintor gate– Vertical lift gates – Automatically lifting gates – counter wt. operated – Float operated – Counter wt. and flood operated – Flap shutters – Automatic tilting gates/ Godbole gates
Most common type of gate used for hydraulic structure i.e. vertical lift gates. 1. Stoney gates 2. Cater piller gates 3. Fixed wheel gates 4. Sliding gates Vertical lift gates provide with wheels on sides to reduce the friction are known as fixed wheel gates and without wheel is known as sliding gate.
• In spillway with high Tail water, Vertical Lift Gates are generally superior to Radial Gates . Trunnion assembly under water is not desirable because of the possibility of debris impinging upon it and causing damage .• Bigger gates require bigger wheels or rollers which in turn necessiate bigger gate groove. Bigger groove create turbulent flow by the side of the piers and also there is a tendency for the floating debris or trees to lodge in these gate grooves. This will prevent smooth operation of gates during flood.• Higher gates are also necessiate in increased height of piers.
• The radial shape provides efficient transfer of hydrostatic loads through the trunnion.• A lower hoist capacity is required.• Radial gates have a relatively fast operating speed and can be operated efficiently.• Side seals are used, so gate slots are not required. This reduces problems associated with cavitations, debris collection, and buildup of ice.• Radial gate geometry provides favorable hydraulic discharge characteristics.
Disadvantages[ 1]To accommodate location of the trunnion, the pier and foundation will likely be longer in the downstream .Larger piers increase cost due to more required concrete and will usually result in a less favorable seismic resistance due to greater height and mass.(2) End frame members may encroach on water passage. This is more critical with inclined end frames.(3) Long strut arms are often necessary where flood levels are high to allow the open gate to clear the water surface profile.
Vertical Gates Involves design of • Skin plate• Vertical And Horizontal Stiffeners And Main girder• Wheels• Seals And Accessories• Guide Rollers• Wheel track And Track base• Sill beam• anchorages
Skin plate and Stiffeners • Skin plate and Stiffeners shall be designed together in composite manner• It shall be designed in bending across the stiffeners or Horizontal girders as applicable. To take care of corrosion the actual thickness of skin plate shall be provided at least 1.5 mm. more than the theoretical thickness computed.• The stiffeners may be of a built up section or of standard rolled section.
Horizontal/Vertical Stiffeners and Main Girder • The Horizontal and Vertical Stiffeners Shall be designed as simply supported or continuous beam depending upon framing adopted for gate.• The spacing between main horizontal girders shall be preferably such that all the girders carry almost equal load.• Maximum deflection of gate under normal condition of loading shall be limited to 1/800 of the span.
Seals And Accessories • Seal shall be fixed by means of seal clamps or S.S.bolts so as to ensure a positive water pressure between the seal and gate and to bear tightly on the seal seat to prevent leakage.
GUIDE ROLLER TRACK SIDE SEAL TRACKVERTICAL GROOVE EQUILIZER PLATE END LIFTING BRACKET VERTICAL STIFFNER PLATE
Guide Rollers • Gate Guide Rollers shall be provided on the sides of the gates to limit the lateral motion of the gate to not more than 6 mm. in either direction.• A minimum of two guide rollers should be provided on each side of the gate to resist the transverse and lateral movement of the gate at same time to prevent the gate for jamming.
Sill Beam • The minimum Width of Seal seat shall be 80 mm. excluding the required chamfer. • The Minimum Thickness of the S.s. plate for low head gates be 6 mm. and for medium and high head gate is 8 mm.• The sill beam may be provided with the corrosion resistant steel flats welded or screwed with corrosion resistant steel sheets. The surface of sill beam may be machined smooth.
Anchorages/ anchor Plates • Anchorages shall be provided in first stage concrete, with suitable block out openings to hold the embedded parts of second stage concrete. The minimum size of Anchor Bolts shall not be less than 16 mm. and anchor plate thickness shall not be less than 8 mm.
1. CREST LEVEL2. F.R.L.3. H.F.L.4. T.W.L.5. TYPES OF SPILLWAY
SIZE OF GATE SHALL BE SPECIFED AS THE CLEAR WIDTHOF OPENING & THE VERTICAL HEIGHT ABOVECREST/SILL OF GATE UPTO THE F.R.L. EXCLUDING FREEBOARD.
• NORMALLY, RADIAL GATE HAS AN UPSTREAM SKIN PLATE BENT TO AN ARC WITH CONVEX SURFACE OF ARC IN U/S SIDE.• THE CENTRE OF ARC IS AT THE CENTRE OF TRUNNION PIN, ABOUT WHICH THE GATE ROTATES.• THE SKIN PLATE IS SUPPORTED BY SUITABLY SPACED STIFFENERS EITHER HORINZONTAL OR VERTICAL . IF VERTICAL STIFFENERS ARE USED, THESE ARE SUPPORTED BY SUITABLY SPACED HORINZONTAL GIRDERS WHICH ARE SUPPORTED BY RADIAL ARMS.• THE ARMS TRANSMIT WATER LOAD TO THE TRUNNION/ANCHOR GIRDER.• SUITABLE SEALS ARE PROVIDED ALONG CURVED ENDS OF GATE & ALONG BOTTOM.• GUIDE ROLLERS ARE ALSO PROVIDED TO LIMIT SWAY OF GATE DURING RAISING/LOWERING. • TOTAL WATER THRUSTS ON GATE ARE TRANSMITTED THROUGH TRUNNION WHICH ARE FASTENED WITH ANCHOR GIRDER.• ANCHOR GIRDER TRANSFERS ALL LOADS TO PIER THROGH HORIZONTAL AND VERTICAL ANCHORAGES.
:1. GATE SHALL BE WATER TIGHT. 2. MAX. PERMISSIBLE LEAKAGE SHOULD NOT BE MORE THAN “5 LTRS./MIN./M. LENGTH OF SEAL”.3. GATE SHALL BE CAPABLE OF BEING RAISED/LOWERED BY HOIST AT SPECIFIED SPEED.4. POWER OPERATED GATES SHALL NORMALLY BE CAPABLE OF OPERATION BY ALTERNATIVE MEANS IN CASE OF POWER SUPPLY FAILURE.5. GATE SHALL BE CAPABLE OF BEING HELD IN POSITION WITHIN RANGE OF TRAVEL TO PASS REQUIRED DISCHARGE WITHOUT CAVITATION & UNDUE VIBRATION.
(A) FIXING THE PARAMETERS LIKE (1) LOCATION OF SILL (2) LOCATION OF TRUNNION (3) TOP OF GATE (4) RADIUS OF GATE (5) LOCATION OF HOIST
THE SILL OF GATE SHALL PREFERRABLY BE LOCATED SLIGHTLY D/S OF CREST TO AVOID CAVITATION OF D/S GLACIS .IN GENERAL PRACTICE , WE PROVIDE 0.25 TO 0.35 m BELOW CREST TOWARDS D/S.
IT SHOULD BE AT LEAST 1.5 M. ABOVE WATER PROFILE (UNDER H.F. L. CONDITION.)RESULTANT HYD. THRUST IN GATE POSITION FOR F.R.L. CONDITION LIES AS CLOSE TO HORI. AS POSSIBLE. (1/3 HEIGHT OF GATE)NOT ALLOWED IN SUBMERGED CONDITION. T.W.L. SHALL BE BELOW 1.0 M.NONE OF ANY PARTS OF CIVIL STRUCTURES INTERFERE WHILE RAISING/LOWERING GATE.
FOR EFFECTS OF WAVE, FREE BOARD SHALLBE PROVIDED ABOVE F.R.L.NORMALLY, TI WILL BE 0.3 M.TOP OF GATE = F.R.L.+0.3 M.
RADIUS OF GATE IS THE DISTANCE FROM CENTRE OF TRUNNION PIN TO INSIDE OF SKIN PLATE.IT SHOULD BE 1.0 TO 1.25 OF HEAD OF WATER. i.e. H TO 1.25 H.LARGE RADIUS SHALL INCREASE PIER DIMENSION.
HOIST SHALL BE SO LOCKATED THAT, ASFAR AS POSSIBLE, HOISTING FORCE ISAPPLIED TO GATE AT LARGEST POSSIBLERADIUS & HOISTING ANGLE DOES NOTCHANGE MUCH DURING TRAVEL OF GATE.
:RADIAL GATE CONSIST OF SKIN PLATESUPPORTED BY VERTICALS WHICH INTURN REST ON HORIZONTAL GIRDER.THE HORINZONTAL GIRDERS ARE MOUNTEDON END ARMS WHICH TRANSMIT HYD.PRESSURE TO ANCHOR TIES (RODS)THROUGH ANCHOR GIRDER.ANCHOR GIRDER TRANSMIT THE LOAD TOPIER THROUGH ANCHOR TIES.THUS HYD. PRESSURE RESISTED BY SKINPLATE IS ULTIMATELY TRANSMITAD TO PIERCONCRETE.
THE SKIN PLATE & STIFFENERS SHALL BE DESIGNED TOGATHER IN A COMPOSITE MANNER.THE STIFFENERS GENERALLY USED ARE TEES, ANGLES OR CHANNELS.THE MINIMUM THICKNESS USED IS “ 8 “ mm. TO TAKE CARE OF CORROSION , THE ACTUAL THICKNESS OF SKIN PLATE BE PROVIDED AT LEAST 1.5 mm. MORE THAN THICKNESS REQUIRED.
MINIMUM NOS. BE USED TO SIMPLIFY THE FABRICATION , ERECTION & MAINTANANCE OF GATES.NOS. TO BE FINALISED BY FOLLOWING CRITERIA : GATE HEIGHT NO. OF GIRDERS UP TO 8.0 M. 2 8.0 TO 12.5 M. 3 ABOVE 12.5 M. 4MAY BE SPACED AS B.M. IN VERTICAL STIFFENERS AT GIRDER SUPPORT ARE NEARLY EQUAL.IT SHOULD BE SUITABLY BRACED TO ENSURE RIGIDITY.IT SHALL BE CHECKED FOR SHEAR AT POINTS WHERE THEY ARE SUPPORTED BY ARMS.
THE NO. OF PAIR OF ARMS SHALL BE EQUAL TONO. OF HORI. GIRDERS.ARMS MAY BE STRAIGHT OR INCLINED.FOR BIGGER SPAN OF GATE, INCLINED ARMS AREPREFFERED.IT SHOULD BE DESIGNED AS COLUMN FOR AXIALLOAD TRASMITTED BY HORI. GIRDER.THE ARMS ARE SUITABLY BRACED IN SUCH WAYTHAT L/R RATIO OF ARM IN LONGITUDINAL &TRANSVERSE DIRECTION IS NEARLY EQUAL.IF THERE IS DIFF. IN H.F.L. & F.R.L., SIDE SHIELDSON TOP OF GATE LEAF ARE PROVIDED TOPROTECT END ARMS AGAINST IMPACT OF WATER.
IT CONSIST OF TRUNNION HUB, TRUNNION PIN,TRUNNION BEARING & TRUNNION BRACKET. TRUNNION HUB: IT SHALL ROTATE @ TRUNNION PIN. ARMS ARE RIGIDLY CONNECTED TO HUB BY WELDED OR BOLTED CONNECTION. IT MAY BE CAST STEEL OR M.S. TRUNNION PIN: IT SHALL NORMALLY BE SUPPORTED AT BOTH ENDS OF TRUNNION BRACKET IT SHALL BE OF CAST STEEL OR FORGED STEEL WITH CHROME PLATING.
TRUNNION BUSH: IT SHOULD BE OF HIGH TENSILE BRONZE. THICKNESS OF BUSH = .08 D + 3 MM., “D” IS PIN DIA. HOWEVER, THICKNESS OF BUSHING IS NOT LESS THAN 12 mm.TRUNNION BRACKET: IT SHALL BE RIGIDLY FIXED TO ANCHOR GIRDER BY BOLTS. IT SHALL TRANSFER TOTAL LOAD FROM TRUNNION TO THE ANCHORAGES. IT SHALL BE OF CAST STEEL.
IT SHALL BE DESIGNED TO WITHSTAND THE TOTALWATER LOAD ON GATE & TRANSFER INTO PIERS.GENERALLY, COMMON ANCHOR GIRDER SYSTEM ISUSED.IT SHALL BE DESIGNED FOR MAX. LOAD , WHENONE GATE IS FULLY CLOSED & ADJACENT GATE ISIN FULLY OPEN POSITION.NOS. OF ANCHORAGES & ROOT DIA. OF THREADEDEND OF ANCHORAGES ARE WORKED OUT AGAINSTTOTAL TENSILE LOAD.
THE EMBEDED LENGTH ARE WORKED OUT FOR BONDSTRESS REQUIREMENT. HOWEVER, MINIMUM LENGTHOF ANCHORAGES SHALL BE 2/3 OF RADIUS OF GATE.WHEN TRUNNION IS KEPT 1/3 HEIGHT OF GATE,ANCHOR GIRDER IS KEPT IN HORIZONTAL POSITION.IF TRUNNION IS KEPT ABOVE 1/3 HEIGHT OF GATE,ANCHOR GIRDER IS KEPT INCLINED AT AN ANGLE “θ”,SO AS TO KEEP THEM PARALLEL IN DIRECTION OFRESULTANT LOAD PASSING THROUGH TRUNNION.
VERY ACCURATE DESIGN,FABRICATION & ERECTIONARE REQUIRED TO BE DONE AS TELESCOPIC FAILUREOF ALL THE GATES WILL TAKES PLACE IN CASE OFFAILURE OF ANY ONE ANCHOR GIRDER.TO AVOID CRACKING OF FACE CONCRETE,THEYSHOULD BE INSULATED TO A MINIMUM OF 500 mm.LENGTH FROM THE FACE CONCRETE.
SILL BEAM: R.S.J. WITH S.S. CLADE PLATE ISPROVIDED ON OGEE.BOTTOM RUBBER SEAL : USUALLY, WEDGE TYPESEAL & IS FIXED ON THE GATE LEAF WITH CLAMPS.SIDE RUBBER SEAL : “Z“ TYPE OR MUSICAL KNOTETYPE IS USED.IN BOTH SIDES OF PIER, WALL PLATE WITHS.S.CLADE PLATE IS PROVIDED.3 TO 6 mm. CONPRESSION IS GIVEN TO RUBBERSEALS TO MAKE IT WATER TIGHT.
WIRE ROPE WALL PLATE SKIN PLATE TOP PLATEZ TYPE RUBBER SEAL
NORMALLY, ROPE DRUM HOIST IS USED.IT COMPRISES OF TWO END REDUCTION UNITS(ERU) & ONE CENTRAL DRIVE UNIT(CDU).E.R.U. CONSIST OF DRUM & 2 TO 4 SETS OF SPURGEARS.C.D.U. CONSIST OF ELECTRIC MOTOR, MAGNETICBRAKE & WORM REDUCTION UNIT. STARTER,RELAYES, CONDUCTORS ETC. ALSO INCLUDED.
NORMALLY, OPERATED BY ELECTRIC POWER FROMGRID SUPPLY.DIESEL GENERATOR IS PROVIDED IN CASE OF GRIDPOWER FAILED.MANNUAL OPERATION THOUGH VERY SLOW ISALSO POSSIBLE .
CONSTRUCTION STAGE OF SPILLWAY PIER : EMBEDED PARTS: – LINE LEVEL: 1. LINE LEVEL IN SILL BEAM & WALL PLATE SHOULD BE PROPERLY MAINTAINED AS PER SPECIFIED TOLERANCES. 2. IF THE FACE TO FACE DIMENSION IS LESS THAN REQUIRED, THE GATE COMPONENT LIKE SKIN PLATE, HORI. GIRDER MAY FAUL WITH WALL PLATE & THE SKIN PLATE WILL HAVE TO BE CUT & THE RUBBER SEAL HOLES FOR FIXING WILL GET DISTURBED.
CONCRETING OF SPILLWAY PIERS : WHILE CONCRETING SPILLWAY PIER AS NECESSARY ALLOWANCE SHOULD BE KEPT FOR BULGING OF CONCRETE. IF CARE IS NOT TAKEN, THE PIER WILL GET BULGED AT SOME PLACES & THE HORI. GIRDERS, ARMS & TRUNNION BRACKET WILL GET FOULED WITH ADDITIONAL CONCRETE. 3 TO 4 INCHES BULGING / UNEVENNESS HAS BEEN OBSERVED IN SOME OF CASES, WHICH REQUIRES ENORMOUS CONCRETE CHIPPING & CONSEQUENTLY COSTS MORE & HINDERS ERECTION TIME SCHEDULE.
STAGE CONCRETE : NORMALLY, CONCRETING FOR EMBEDDED PARTS ARE DONE IN STAGES TO ERECT 1ST & 2 nd STAGE EMBEDDED PARTS. THE SURFASCE OF PREVIOUS STAGE CONCRETE SHOULD BE KEPT ROUGH & THE CONCRETING OF NEXT STAGE SHOULD BE VIBRATED TO HAVE PROPER BOND BETWEEN STAGE CONCRETE. SOMETIMES, DOWEL BARS BETWEEN STAGE CONCRETE MENTIONED IN DRG ARE NOT PROVIDED. IN THAT CASE, IT IS FEARED THAT DUE TO INSUFFICIENT BOND, THE LAST STAGE CONCRETE MAY GET COLLEPSED. IF NOT COLLAPSED, LEAKAGE MAY OCCUR THROUGH STAGE CONCRETE SURFACE, IF PROPER BOND IS NOT ATTAINED BETWEEN TWO STAGE CONCRETE.
IN CASE OF BONDED MAIN ANCHORAGES, THE INITIAL 1.5 TO 2.0 m LENGTH NEAR ANCHOR GIRDER IS REQUIRED TO BE INSULATED WITH GREESE & POLYTHELENE PAPER OR WITH COARK MASTIC OR ASPHALT TO AVOID SURFACE CRACKING IN THE PIER. HOOKS ARE PROVIDED IN BONDED MAIN ANCHOR RODS AT END.AS FAR AS POSSIBLE, THE JOINTS IN RODS SHOULD BE AVOIDED. IF AT ALL IT IS PROVIDED, IT SHOULD BE DONE WITH PROPER DESIGNED COUPLING & NOT WITH THE WELDING.
STAINLESS STEEL SHEETS/ PLATES ARE CLADED TO WALL PLATE & SILL BEAM TO HAVE SMOOTH & NON CORREDED SURFACE FOR RUBBER SURFACE. THE WELDING SHOULD BE DONE SUCH THAT THERE WILL NOT BE ANY BURR ON SURFACE. ANY UN EVEN SURFACE OF CLAD PLATE SHOULD BE AVOIDED , OTHER‐WISE, IT WILL DAMAGE RUBBER SEAL.
(1) SKIN PLATE BENDING : The bending of skin plate should be done true to its radius. Instances have been noted of gate failure because of non‐similarity in radius of gate & skin plate bending. In such case the load will not be transferred through trunion centre & gate may get failed from arm assembly.(2) BENDING OF VERTICAL STIFFENERS : T‐verticals of gate leaf are bend to get correct radius through‐out length of vertical height with T‐ bending machine, not with screw jack.
(3) TRUNNION HUB : Shape/size of trunion hub should be correctly casted/ fabricated with correct angle.(4) casting : All casting of rollers, trunion assembly, gears etc. should be free from any defects like blow holes, cracks, gas inclusion etc.
Important attendance during erection forsmooth function of gates: Concreting of sill beam & wall plate block‐out should not be done before erection of gate leaf other‐wise there will not be any chance of adjustment in alignment. Seals over the gate leaf should not be fixed before erecting wall plate & seal beam. Erection of hoist should be completed before on set of monsoon if the gates are erected. Otherwise, some latching arrangement has to be installed to keep gates in fully open position.
A no. of occasions questions has been raisedregarding whether we should go for u/s ord/s suspension type of hoist in case of RadialGates.In Gujarat, all the Radial Gates have beendesigned with up‐stream suspension type ofHoist only, except that for Ukai Project , amulti purpose project, where in far 51 ft. x 46ft. size gates down –stream suspension typeof hoist have been designed.
Clause 6.5.3 of I. S. 4623 – 2000 regarding“Recommendations for structural design ofRadial Gates. “ suggest that “ The hoist shall beso located , that , as far as possible, the hoistingforce is applied to the gate at the largestpossible radius and hoisting angle does notchange much during travel of gate”. Thiscondition gets satisfied in case of u/ssuspension only.
Where as in down stream suspension type of hoist, the rope is required to be fixed towards thetrunion and during the travel of the gate thehoisting angle goes on changing a considerableextent.Cl. 6.5.4 of the same I.S. 4623‐2000 , also suggeststhat “ In the case of hydraulic hoist the connectionto the gate is on d/s of skin plate while in case ofrope drum hoist, the same is generally preferredon the u/s of skin plate”.
Favorable Aspects For U/S Suspension Type of Hoists: Lifting efforts on hoist get reduced. Hoisting angle remains unchanged during travel of gate. Pier length comparatively gets reduced.Unfavorable Aspects : Not easily accessible for inspection and maintenance . Replacement of wire rope in emergent condition not possible.
Precautionary Measures of U/S Suspension type hoist considered: Generally, wire ropes etc. are periodically inspected/maintained/replaced when reservoir gets depleted below crest level. Incase of big sized gates like, 51 ft. X46 ft., 49 ft. X35 ft., crest stop‐logs are generally being thought off depending upon low water level . In case of such an eventuality like failure of wire rope, which how‐ever being rare occurrence , stop‐logs can be lowered and wire ropes get replaced.
Provision for 10 % gates as standby is alwaysbeing made. i.e. Contingency of certain gates beinginoperative is kept in view. Thus, When wire ropesgets snapped, this 10 % provision takes care of.While selecting for U/S suspension. The ropesselected should be galvanized one.The ropes should be well lubricated from time totime as per the manufacturer’s recommendation.
The uninterrupted leakage of waterthrough side seals of gate which fallsdirectly on joint point of girder andarm resulting failure of joint andfinally entire project.
• Due to short length, some of the main horizontal anchor rods are not fastened with anchor girders, which may ultimately resulted into failure of anchoring arrangement of gate to pier.
• Some of the main anchor rods are not extended/bolted up‐to D/S flange of anchor girder which may be resulted into failure of anchoring system of radial gates.
The vertical anchor rods of gates are notproperly bolted with pedestal base plate ofanchor girder to the base plate of pier, ultimatelyup‐thrust/down‐thrust may overturn theanchoring system of radial gates. This point mayplease be immediately attended to compliedwith to ensure the safety of gate.
• The pedestal connectivity of anchor girder seemed to be weaker in terms of not providing requisite no. of studs as specified by designers on drawing.
• Trunnion pin sheath cover is not provided in most of the gates. It should be provided to avoid jamming of mud etc.
TOLERENCES FOR COMPONENTS OF GATESCOMPONENTS TOLERENCES( 1 ) Guide roller/Guide Shoe: +1.00 mm.Distance between centre line of gate ‐‐ 2.00 mm& face of side seal.( 2 ) Side Seal ;Distance between centre line of gate & + 1.00 mm. to – 1.00 mm.face of side seal( 3 ) Trunion bearings : (a) Co linearity of centre lines of both + 0.25 mm. to – 0.25 mm.the trunion bearings (b) Horizontality of centre lines of both the trunion bearings + 0.25 mm. to – 0.25 mm. (c) Parallel distance of centre line of both the trunion bearings from + 3.00 mm to – 3.00 mmupstream bottom edge of skin plate (d) Tolerances in diameters of pin, To suit diameters and required fitsbush hub and bracket of trunion assembly
TOLERENCES FOR EMBEDED PARTSCOMPONENTS TOLERENCES(A) Wall Plate & Sill Beam(a) Distance Between centre line of +0.00 mmopening & face of wall plate at sill end. ‐2.00 mm.(b) Distance Between Centre line of + 2.00 mm.opening & face of wall plate at top end. ‐ 0.00 mm.(c) Straightness of face of wall plates & Offset at joints to be ground smoothsill plates.(d) Normally of face of wall plates to + 0,00 degreegate sill & centre line of trunion ‐ 0.00 degreebearings.(e) Alignment of sill plate in horizontal + 0.25 mm. TO – 0.25 mm.plane.