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PURPOSE OF USING VALVES Valve Va Valves lvess ar aree us used useed ed to co cont ntrol ntro roll th thee fl flow flo low ow w of of liquids, liqui liq uids, ds, solids and ga solids gase gases gas ses ess in ind industr ustrial ial as we well ll as dom domest domestic estic ic situ si situations tuat atio ions ns aan and nd are one of the ma majo major jor piping pipi pi ping ng components.. components The mo The most mos ost stt com commo mon n an and d fam familia fami fa milia iliar liarr va valv valves lves es aar are re e th thee taps us taps used ed iin n the th e ho hom home hom me to con contro cont co ntro trol roll th the the e fl flow ow of of hot hot and co and cold ld water. wate wa terr. In In th the t he he oil oil ind industr ustry, y, va valve valves valv lves es s aar are re a majo ma major jorr el elem emen entt iin n th the the co cont con ontr ntro trol rol oll of of operations. oper op erat atio ions ns. Abou Ab About outt 88-10 -10 10% %o of f th the the tota total totall capita capital capitall exp expend expenditure enditu iture re of of the chem chemical chemi che mical ical cal ind industr industry ustry y is use used used d for for procur procuremen ementt of valves.. valves
PRESENTATION ON MECHANICAL VALVES BY ALOK KUMAR SINGH
VALVE CLASSIFICATION BASED ON FUNCTION
VALVES ARE USED FOR ONE OR MORE OF THREE MAIN PURPOSES
VALVES
ON/OFF
To control the rate of flow (throttle); To shut off/permit flow (ON/OFF function); To isolate systems and protect products.
REGULATION
GLOBE
BALL
NEEDLE
FLUSHBOTTOM
PLUG
BUTTERFLY
FLOAT
PISTON
DIAPHRAGM
FOOT
DIAPHRAGM
PISTON
LINE BLIND
BUTTERFLY
PINCH
FLANGED ENDS
BUTT WELD ENDS
MULTI-PORT
PINCH VALVE
VALVE CLASSIFICATION BASED ON MATERIAL OF CONSTRUCTION
VALVES
SOCKET WELD ENDS
CHECK
SPECIAL
GATE
VALVE CLASSIFICATION BASED ON END CONNECTIONS
SCREWD ENDS
NON-RETURN
VALVES
SOCKETTED ENDS
WAFER TYPE ENDS
CAST IRON
BRONZE
GUN METAL
CARBON STEEL
SS
ALLOY CARBON STEEL
POLY PROPY-LENE
SPECI AL SPECI ALLOY
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STANDARDS OF MANUFACTURE
Metric/Imperial dimensions; British Standards - BS German Standards - DIN; US Standards - ANSI (previously ASA); American Petroleum Institution - API. (flanges and other equipment are commonly used in the oil industry Valves are rated according to the maximum pressure and temperature at which they can can safely be used used..
VALVE TYPE SELECTION CRITERIA
Some API standard are : API 6D6D- Pipe Line Valve API 600 – Steel Gate Valve Valve API 602602- Carbon Steel Gate Valves Valves API 609609- Butterfly Valves Valves Some BS standard are : BS 14141414- Gate Valve For For Petroleum Industry Industry BS 18681868- Steel Check Valve For For Petroleum Petroleum Industry BS 16731673- Steel Globe Valve For For Petroleum Petroleum Industry BS 51555155- Butterfly Valve Valve BS 53515351- Steel Ball Valve Valve BS 53535353- Carbon Steel And Alloy Alloy Steel Steel Plug Valve
VALVE STROKE(OPENNESS) VS THE FLOW
Equal Percentage: equal increments of
Size limitations
valve travel produce an equal percentage in flow change
Cost , pressure and flow rate
vave rave s to the valve stoke
Service
Quick opening: large increase in flow with
Maintenance requirements
a small change in valve stroke
VALVE CHARACTERISTICS EQUAL-PERCENTAGE VALVE LINEAR VALVE. QUICK-OPENING VALVE.
rec y propor ona
Equal Percentage (most commonly used valve control)
Used in processes where large changes in pressure drop are expected Used in processes where a small percentage of the total pressure drop is permitted by the valve Used in temperature and pressure control loops
Curve A = Quick Opening Curve B = Linear Curve C = Equal %
Linear Used in liquid level or flow loops Used in systems where the pressure drop across the valve is expected to remain fairly constant (ie. steady state systems) Quick Opening Used for frequent onon-off service Used for processes where "instantly" large flow is needed (ie. safety systems or or cooling water water systems) systems)
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GATE VALVES
GATE VALVE
Used when when a ti tight ght shut shut--off is required requ ired & there must be straight--line flow of fluid with min. resistance straight Quick Opening valve Infrequent operation Gate usually wedgewedge-shaped or a vertical disc as in the diagram A lication: Oil, as, air, slurries , heav li uids , steam , no condensing gases, and corrosive liquids Adv:: high capacity,No flow restrictions & low cost Adv cost Disadv:: Disadv
GATE OR DISC
Poor throttling Cavitate at low pressure drops Gate valves should not be used where frequent operation is required
BALL VALVE To provide a quick opening, linear & simple shutshut-off off For Fully open/closed, limitedlimited-throttling throttling Higher temperature fluids Ball has opening through centre. when this opening is in line with the inlet & outlet ports, flow will be allowed.when ball is turned through 90 deg. No flow can takes place Application: Normally found in seawater, sanitary, trim and drain, slurry and hydraulic systems Adv:: Adv Offer minimum resistance to flow Tight sealing with low torque Low cost & High capacity Low leakage and maintenance Operation, reliability, durability, and capability of withstanding high pressures Disadv:: Disadv Prone to cavitations Not Suitable For Lines Subject To Pulasting Flow Poor throttling characteristics Expensive
PLUG VALVE
BALL VALVE
BALL
PLUG VALVE
To provide a quick, simple shutshut-off Not Common In Sizes Over 6 Inch Not Suitable For Lines Subject To Pulasting Flow Controls flow using a plug with a hole through it. Plugs can be made of rigid materials such as Teflon¨ Teflon¨, making t em eeaa or g -pur ty Adv:: Adv Good for high pressure applications Easy to operate Provide a tight shutoff Disadv Plugs may freeze if not operated for a long period of time
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DIAPHRAGM VALVE DIAPHRAGM VALVE For Low Pressure Corrosive Service As ShutShut-off Valves Diaphragm moves up and down to operate the valve Diaphragm materials available in Nitrile, Hypalon, Neoprene, PTFE, etc. Application : Slurry Services, Suspended Particles (Elastomeric Diaphragm only) & Severe Chemical A v: v: Can Be Used Where Leakage Cannot Be Tolerated Disadv: Can Only Withstand A Maximum Operating Pressure 7 to 10 Kg/Cm2 g Require frequent maintenance as damage to diaphragm occur Cannot Withstand Temperature Above 400 Deg F
Visual I ndicator Travel Stop
Hand wheel
Bonnet
Compressor
Diaphragm
One Piece Molded Flange
GLOBE VALVES
Panel Mount Provision
GLOBE VALVE
Throttling service/flow regulation valve Linear and Equal percentage valve Frequent operation Application: steam, air, water, oil lines, corrosive substances & slurries Disc attached to valve stem rests against seat to shut off flow of fluid Adv:: Adv Efficient throttling & Accurate flow control Available in multiple ports Disadv:: Disadv flow resistance High pressure drop More expensive than other valves
NEEDLE VALVE
NEEDLE VALVE
Most accurate flow control among the valves Similar To Globe Valve Except Disc Is Pointed At End .Steel Valves Are Often Made From Bars stock Arc Rugged. Valves 2 Inch. And Smaller For Use On Pilot Plants And Bench Scale Equipment And Instrument Service .
Good For Manual Flow Control .Ground Joint Union Bonnet Connection Preferable. Disadv:
Positive Shut –Off –Off Not Always Posible Or Desrible. In some designs, seat is scored If Shut Down Tightly
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BUTTERFLY VALVE
BUTTERFLY VALVES Linear, Equal percentage & Positive shut –off quarter turn valve Fully open/closed or throttling services Frequent operation Minimal fluid trapping in line The disc or wafer rotates about a vertical axis & can be turned through 90 deg. .The disc seals against the opening to cut of flow & can be positioned at a point between fully closed and fully opens as required Application: Liquids, gases, slurries, liquids with suspended solids and ventilation systems Small, light-weight, easy operation ,low cost ,minimum maintenance, drip tight shut –off , quick-acting & reliability High capacity, Low pressure drop& self-sealing so they don’t require an additonal flange gasket for installation Can be used for vacuum service
Disadv: High torque required for control Prone to cavitations at lower flows Leaks early & only low-flow throttle The material used for seats restrict its use for high temperature application
CHECKVALVES: HOW THEY WORK…
CHECK VALVES Allow flow in one direction only. Flow forces a ball or disk in one direction to open the valve; when flow stops, the ball or disk seats to close the valve. An important concept in check valves is the cracking pressure which is the minimum upstream pressure at which the valve will operate. Typically the check valve is designed for and can therefore be specified for a specific cracking pressure. One common application is in the discharge line of a centrifugal pump to prevent reverse suction Adv:: Adv
CORRECT FLOW
REVERSE FLOW
Check valves are automatic in action
SWING CHECK CHECK VALVE CLASSIFICATION
CHECK VALVE
SWING
Controls direction of flow It has a hinged disk. When the water flow reverses, water pressure pushes the disk and closes the valve Application: Suspended Particles,high velocity Adv:: Adv Minimum Pressure Drop is Required Best For Liquids And For Larger Line Sizes (Above 2”)
LIFT
Disadv: WAFER
PISTON LIFT
BALL LIFT
NON-SLAM
Not Suitable In Line Subject To Pulsating Flow Some Styles Operates Only In A Horizontal Position
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SWING-CHECK VALVE
WAFER CHECK VALVE Wafer check valves are flangeless swing check valve covered under regulatory code API 594 Adv:: Adv , reduced water hammer and are compact Disadv: producing relatively high head losses excessive wear under some operating conditions
PISTON LIFT CHECK VALVE
WAFER CHECK VALVE
In a lift check valve, upward regular flow raises the piston and opens the valve, and reverse flow pushes the disk down to its seat and stops the backflow v: Good For Vapours ,Steam ,And Water. Suitable For Pulsating Flow Disadv: Many Design But For Horizontal Service Only. Not Common In Sizes Over 6 Inch. Not Recommended For Service Which Deposit Solids
PISTON LIFT CHECK VALVE
BALL LIFT CHECK VALVE Controls direction of flow ball is located at end of stem and lifts to allow flow Application: Space Limitation Problems, Minimum shut off is 5 psi Adv: Stop Flow Reversal More Rapidly Than Others Good For Viscous Fluids Which Deposit Solid Residues That Would Impair Operation Of Other type Vertical Or Horizontal Installation Is possible Disadv: Not Common in Sizes Over 6 Inch. Not Suitable For Lines Subject To Pulsating Flow
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BALL LIFT CHECK VALVE NON-SLAM CHECK VALVE The NonNon-slam Check Valve Is A Spring Spring--loaded Lift Check Valve With A Modified Design Of The Body The Valve Is Designed In Such Way That Same Can Be Sandwiched Between The Two Flanges. Here The Disc Is Held In Position By A Spring Which Is Housed In A Housing Cap Or Yoke
IBR VALVES
INSPECTION AND TESTING Inspection plan to be submitted to Purchaser by supplier during order FOR FORGED VALVES/ CAST STEEL VALVES Visual and dimensional inspection. Review of material test certificates. Any mandatory of supplementary test. Hydrostatic test of all valves. Strip check on 1% of total ordered quantity of valves at random to verify compliance with specification requirements Review of radiographs / radiographic reports and reports of any other NDT tests, for cast steel valve only
TERM USED FOR VALVE SPECIFIATION Pressure –t – temperature em per at ur e rratings: at in gs: Pressure –temperature –temperature rating is the maximum allowable sustained non shock pressure at the corresponding tabulated temperature. These are listed in ASME B16.34 Class: The valve is specified by the pressure rating of the body of the valves. American Standard specified the following classes (i.e. 150# ,300# ,400# ,600#,900# ,1500# & 2500 #) Trim: The trim is comprised of stem ,seat surfaces ,back seat bushing and other small internal parts that’s normally contact the surface fluid. API 600 specifies trim number in table 3 of the standard ,it specifies the types of material which can be used for the parts with its typical specification and grade.
Valves described as “I BR Valves” shall be in accordance wit h the lat est I BR (I ndian Boiler Regulations) as well as the ot her requirements specified in t he specification .
For SW / BW end carbon steel valves under “ ” , ”, shall conform to the following : Carbon Car bon ((Max.) Max.) : 0.25% Ot h e rs ((S, Others S, P, M Mn) n) : As per p er I B BR R For all “IBR Valves” test certificate in form IIIIII -C C shall be furnished, duly signed by IBR inspection authority or an IBR approved representative All valves shall be painted red
TRIM PARTS OF COMMON VALVES GATE
GLOBE
SWING
LIFT CHECK
STEM
STEM
SEAT RING
DISC GUIDE
SEAT RING
SEAT RING
DISC HOLDER
SEAT RING
WEDGE RING
DISC NUT
SIDE PLUG
BUSHING
BUSHING
HOLDER PIN
DISC NUT PIN
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Wetted parts: All parts which come in contact with the service fluid are called the wetted parts .
Wire drawing : This term is used to indicate the premature erosion of the valve seat caused by excessive velocity between seat and seat disc A WOG (water -oiloil-gas, relatively cool liquids) disc is best defiance against wire drawing because its resiliency make it easier to close tightly. Stem discs are of harder material and to be closed carefully to prevent wire drawing i , i i ii-refrigeration. The ice formation on the wedge will obstruct movement thereby increasing the leak through seat further
Straight –t – through hr ou gh flow fl ow : This refer to the valve in the closing element is retracted entirely so that there is no restriction of flow
Quarter –t – turn ur n vvalve: alv e: This refers to the valve where the entire operation of valve is achieved by 90 deg. Turn of the closing element
UPSTREAM PRESSURE: Pressure of the fluid entering the valve, sometimes refers to as inlet or supply pressure.
DOWNSTREAM PRESSURE: Pressure of the fluid discharged from the valve, sometimes refers to as outlet or reduced pressure.
LDAR: Signifies “ leak detection and repair” to ensure that the fugitive emission standards of EPA are met.
LAER: Signifies “ lowest achievable emission rate ” is the minimum rate of fugitive emission which is achieved by deploying proper sealing arrangements
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