full lift safety valve factory

1 Piece Ball Valve1 Piece Cast Iron Screwed Ball Valve1 Piece Flanged Ball Valve1 Piece Screwed Ball Valve2 Piece Ball valve2 Piece Cast Steel Ball Valve2 Piece Flanged Ball Valve2 Piece Forged Steel Ball Valve2 Piece Screwed Ball Valve3 Piece Ball Valve3 Piece Cast Iron Ball Valve3 Piece Cast Steel Ball Valve3 Piece Flanged Ball Valve3 Piece Forged Steel Ball Valve3 Piece Reduced Port Ball Valve3 Piece Screwed Ball Valve3 Way Converging and Diverging Control Valve3 Way Plug Valve3 Way Pneumatic Diaphragm Control ValveAir ValveAlloy 20 2 Piece Ball ValveAlloy 20 2 Piece Screwed Ball ValveAlloy 20 3 Piece Ball ValveAlloy 20 3 Piece Screwed Ball ValveAlloy 20 Ball ValveAlloy 20 Dual Plate Lug Type Check ValveAlloy 20 Floating Ball ValveAlloy 20 Swing Check ValveAlloy 20 Trunnion Mounted Ball ValveAlloy 20 ValvesAlloy 20 Wafer Butterfly ValveAlloy Butterfly ValveAlloy Check valveAlloy Dual Plate Wafer Check ValveAlloy Flanged Gate ValveAlloy Flanged Globe ValveAlloy Gate ValveAlloy Gate ValvesAlloy Globe ValvesAlloy Lug Butterfly ValveAlloy Plug ValveAlloy Pressure Seal Globe ValveAluminium Bronze 3 Piece Ball ValveAluminium Bronze Ball ValveAluminium Bronze Butterfly ValveAluminium Bronze Check ValveAluminium Bronze Floating Ball ValveAluminium Bronze Gate ValveAluminium Bronze Lug Butterfly ValveAluminium Bronze Swing Check ValveAluminium Bronze Triple offset Lug Butterfly ValveAluminium Bronze Trunnion Ball ValveAluminium Bronze valvesAluminium Bronze Wafer Butterfly ValveAluminium Dual Plate Wafer Check ValveAluminum Bronze Globe ValveAngle Globe ValveANSI Gate ValveANSI Globe ValveAPI Aluminium Bronze Triple offset Lug Butterfly ValveAPI Gate ValveAPI Globe ValveAustenitic Steel Big Size Ball ValveAustenitic Steel ValvesAWWA Butterfly ValveAWWA Gate ValveAWWA Non Rising Stem Gate ValveAWWA OS&Y Gate ValveAWWA StrainerAWWA Wafer Butterfly ValveAWWA Y StrainerBalancing ValveBall Float Steam TrapBall ValveBellow Seal Globe ValveBi Directional Knife Gate ValveBimetallic Steam TrapBlock and Bleed valveBrass Ball ValveBrass Ball ValvesBrass Check ValvesBrass Flanged Ball ValveBrass Flanged Gate ValveBrass Flanged Globe ValveBrass Gate ValveBrass Gate ValvesBrass Globe ValveBrass Globe ValvesBrass Safety ValveBrass Swing Check ValveBrass ValveBrass Vertical Check ValveBrass Y StrainerBronze Butterfly ValveBronze Check ValveBronze Flanged Gate ValveBronze Flanged Globe ValveBronze Floating Ball ValveBronze Gate ValveBronze Gate ValvesBronze Globe ValveBronze Globe ValvesBronze Swing Check ValveBronze ValveBronze Wafer Butterfly ValveBronze Wafer Check ValveBS Cast Iron Gate valveBS Cast Steel Gate ValveBS Ductile Iron Gate ValveBS Globe ValveBS Non Rising Stem Gate ValveBS NRS Carbon Steel Gate ValveBS NRS Cast Iron Gate ValveBS NRS Ductile Iron Gate ValveBS Rising Stem Gate ValveBS Soft Seat Gate ValveBS Stainless Steel Gate ValveButterfly ValveCarbon Steel Bellow Seal Globe ValveCast Floating Ball ValveCast Iron And Cast Steel Ball ValveCast Iron Diaphragm ValveCasting Trunnion Ball Valvecheck valveConnection Lift Plug ValveControl ValveCryogenic Ball ValveCryogenic Check ValveCryogenic Emergency Cut off ValveCryogenic Gate ValveCryogenic Globe ValveCryogenic Long Stem Globe ValveCryogenic Pneumatic Actuated Globe ValveCryogenic Short Stem Globe ValveCryogenic Steam Jacket Globe ValveCryogenic ValveDiaphragm ValveDIN Globe ValveDIN Non Rising Stem Ductile Iron Gate ValveDIN Non Rising Stem Gate ValveDIN NRS Cast Iron Gate ValveDIN Rising Stem Cast Iron Gate ValveDIN Rising Stem Ductile Iron Gate ValveDIN Rising Stem Gate ValveDIN Soft Seat Gate ValveDirect Acting Pressure Reducing ValveDouble Block and Bleed Ball ValveDouble Disc Gate ValveDouble Eccentric Butterfly ValveDouble Offset Butterfly ValveDouble Orifice Air Release ValveDouble Orifice Kinetic Air ValveDual Plate Lug Check ValveDual Plate Wafer Check ValveDuctile Iron Diaphragm ValveDuplex 1B 3 PC Ball ValveDuplex 3 Piece Ball ValveDuplex Basket StrainerDuplex Butterfly ValveDuplex Check ValveDuplex Dual Plate Lug Type Check ValveDuplex Dual Plate Wafer Check ValveDuplex Floating Ball ValveDuplex Gate ValveDuplex Globe ValveDuplex High Pressure Ball ValveDuplex Lug Type Butterfly ValveDuplex Steel Ball ValveDuplex steel ValveDuplex Swing Check ValveDuplex Top Entry Ball ValveDuplex Trunnion Mounted Ball ValveDuplex Wafer Butterfly ValveEccentric Plug ValveElectric 3 Way Control ValveElectric Actuated 2 Piece Ball ValveElectric Actuated 2 Piece Flanged Ball ValveElectric Actuated 2 Piece Screwed Ball ValveElectric Actuated Ball ValveElectric Actuated Butterfly ValveElectric Actuated Flanged Ball ValveElectric Actuated Floating Forged Ball ValveElectric Actuated Gate ValveElectric Actuated Globe Control ValveElectric Actuated Globe ValveElectric Actuated High Pressure Ball ValvesElectric Actuated High Pressure Direct Mounting Ball ValvesElectric Actuated Lug Butterfly ValveElectric Actuated Metal-Seated Trunnion-Mounted Forged Ball ValveElectric Actuated Three Piece Ball ValveElectric Actuated Three Way Ball ValveElectric Actuated Trunnion-Mounted Casting Ball ValveElectric Actuated ValvesElectric Actuated Wafer Butterfly ValveElectric Cage Type Control ValveElectric Control ValveElectric Double Seat Control ValveElectric O-type Shut-off Control ValveElectric Single Seat Control ValveF22/Alloy Steel Pressure Seal Globe ValveF317L Gate ValveF317L Globe ValveF317L ValvesF321 Gate ValveF321 Globe ValveF321 ValvesF347 3 Piece Ball ValveF347 Ball ValveF347 Butterfly ValveF347 Check ValveF347 Dual Plate Lug Type Check ValveF347 Dual Plate Wafer Check ValveF347 Floating Ball ValveF347 Gate ValveF347 Globe ValveF347 Lug Type Butterfly ValveF347 Swing Check ValveF347 Trunnion Mounted Ball ValveF347 ValvesF347 Wafer Butterfly ValveF44 Gate ValveF44 Globe valvesF44 ValvesF51 Super Duplex Ball ValveF53/F55 Super Duplex Globe ValveFeed Water Control ValveFlanged Butterfly ValveFlanged Knife gate ValveFloat Control ValveFloating Ball ValveFluorine Lined Single Seat Control ValveFoot ValveForged Cryogenic Trunnion Ball ValveForged Floating Ball ValveForged Steel Ball ValveForged Steel Gate ValveForged Steel Globe ValveForged Steel Swing Check ValveForged Trunnion Ball ValveFull Lift Pressure Safety ValveFull Lift Safety ValveFully Welded Ball ValveGate ValveGlobe ValveHastelloy Ball ValveHastelloy C276 2 Piece Flanged Ball ValveHastelloy C276 2 Piece Screwed Ball ValveHastelloy C276 3 Piece Screwed Ball ValveHastelloy C276/B3 3 Piece Ball ValveHastelloy C276/B3 Butterfly ValveHastelloy C276/B3 Dual Plate Lug Type Check ValveHastelloy C276/B3 Dual Plate Wafer Check ValveHastelloy C276/B3 Floating Ball ValveHastelloy C276/B3 Gate ValvesHastelloy C276/B3 Globe ValveHastelloy C276/B3 Lug Butterfly ValveHastelloy C276/B3 Swing Check valveHastelloy C276/B3 Trunnion Mounted Ball ValveHastelloy C276/B3 ValvesHastelloy C276/B3 Wafer Butterfly ValveHastelloy Check ValveHeavy Duty Investment Casting Ball ValveHigh Performance Lug Butterfly ValveHigh Performance Wafer Butterfly ValveIncoloy 2 Piece Ball ValveIncoloy 3 Piece Ball ValveIncoloy Gate ValveIncoloy Globe ValveIncoloy ValvesInconel 2 Piece Ball ValveInconel 3 Piece Ball ValveInconel Ball ValveInconel Butterfly ValveInconel Check ValveInconel Dual Plate Lug Type Check ValveInconel Dual Plate Wafer Check ValveInconel Floating Ball ValveInconel Gate ValveInconel Globe ValveInconel Lug Butterfly ValveInconel safety relief valveInconel Swing Check ValveInconel Trunnion Mounted Ball ValveInconel ValveInconel Wafer Butterfly ValveInverted Bucket Steam TrapInvestment Casting Ball ValveJacketed Ball ValveJacketed Plug ValveKnife Gate ValveLift Check valveLow Lift Pressure Safety ValveLow Lift Safety ValveLubricated Plug valveLug Butterfly ValveMonel 2 Piece Ball ValveMonel 3 Piece Ball ValveMonel 400 2 Piece Flanged Ball ValveMonel 400 ValvesMonel Ball ValveMonel Butterfly ValveMonel Check ValveMonel Dual Plate Lug Check ValveMonel Dual Plate Wafer Check ValveMonel Floating Ball ValveMonel Forged Trunnion Mounted Ball ValveMonel Gate ValveMonel Globe ValveMonel High Pressure Ball ValveMonel Lug Type Butterfly ValveMonel Swing Check ValveMonel Top Entry Ball ValveMonel Trunnion Mounted Ball ValveMonel ValvesMonel Wafer Butterfly ValveNeedle valveNon Slam Swing Check ValveNon-Lubricated Sleeved Plug ValveNon-Rising Stem Gate ValveNon-Slam Swing Check ValveOrbit Plug ValvePilot Operated Pressure Reducing ValvePilot Operated ValvePressure Relief ValvePiston ValvePlug ValvePlunger ValvePneumatic Actuated 2 Piece Ball ValvePneumatic Actuated 2 Piece Flanged Ball ValvePneumatic Actuated Ball ValvePneumatic Actuated Butterfly ValvePneumatic Actuated Flanged Ball ValvePneumatic Actuated Flanged Butterfly ValvePneumatic Actuated Gate ValvePneumatic Actuated Globe type Control ValvePneumatic Actuated Lug Butterfly ValvePneumatic Actuated Three Piece Ball valvePneumatic Actuated Three Way Ball valvePneumatic Actuated Three Way Heavy Duty Ball ValvePneumatic Actuated Two Piece Ball ValvePneumatic Actuated ValvesPneumatic Actuated Wafer Butterfly ValvePneumatic Angle Control ValvePneumatic Angle Seat Control ValvePneumatic Angle Type High Pressure Regulating Control ValvePneumatic Bi Directional Knife Gate valvePneumatic Cage Control ValvePneumatic Control ValvePneumatic Double Seat Control ValvePneumatic Flow Control ValvePneumatic Knife Gate ValvePneumatic Metal Seat Flanged Ball ValvePneumatic Single Seat Globe Control ValvePneumatic Sleeve Type Control ValvePneumatic Three piece Ball ValvePneumatic Three Piece Flanged Ball ValvePneumatic Three Way Ball ValvePneumatic Three Way Flanged Ball ValvePneumatic Trunnion Casting Ball ValvePneumatic Trunnion Forged Ball ValvePneumatic Trunnion Forged Metal Seat Ball ValvePneumatic Unidirectional Knife Gate ValvePressure Reducing ValvePressure Safety ValvePressure Seal Gate ValvePressure Seal Globe ValvePressure Seal Swing Check ValveRotary Airlock ValveSafety ValveSimplex Basket StrainersSingle Orifice Air ValveSingle Plate Wafer Check ValveSlab Gate ValveSlurry Knife Gate ValveSoft Seal Gate ValveSpeciality ValveSS304 Bellow Seal Globe ValveSS316 Bellow Seal Globe ValveSS316L Gate ValveSS316L Lug Butterfly ValveSS316L Wafer Butterfly ValveSteam Pressure Reducing ValveSteam Safety ValveSteam TrapStrainersSuction DiffuserSuper Duplex 2 Piece Ball ValveSuper Duplex 3 Piece Ball ValveSuper Duplex 5A Flanged Gate ValveSuper Duplex 5A Globe ValveSuper Duplex 5A Swing Check ValveSuper Duplex Ball ValveSuper Duplex Butterfly ValveSuper Duplex Check ValveSuper Duplex Dual Plate Lug Type Check ValveSuper Duplex Dual Plate Wafer Check ValveSuper Duplex Floating Ball ValveSuper Duplex Gate ValveSuper Duplex Gate ValvesSuper Duplex Globe ValveSuper Duplex High Pressure Ball ValveSuper Duplex Knife Gate ValveSuper Duplex Lug Butterfly ValveSuper Duplex Pressure Reducing ValveSuper Duplex Top Entry Ball ValveSuper Duplex Trunnion Mounted Ball ValveSuper Duplex ValvesSuper Duplex Wafer Butterfly ValveSurge Anticipator ValveSwing Check ValveThermal Safety ValveThermodynamic Steam TrapThermostatic Steam TrapThree Piece Flanged Ball ValveThree Way Ball ValveThrough Conduit Knife Gate ValveTilting Disc Check ValveTitanium 3 Piece Ball ValveTitanium Ball ValveTitanium Butterfly ValveTitanium Check ValveTitanium Dual Plate Lug Type Check ValveTitanium Dual Plate Wafer Check ValveTitanium Floating Ball ValveTitanium Forged Trunnion Mounted Ball ValveTitanium Gate ValveTitanium Globe ValveTitanium Gr.2 2pc Flanged Ball ValveTitanium Gr.2 3pc Ball ValveTitanium Gr.5 2pc Flanged Ball ValveTitanium Gr.5 3pc Ball ValveTitanium Lug Butterfly ValveTitanium Swing Check ValveTitanium Trunnion Mounted Ball ValveTitanium valvesTitanium Wafer Butterfly ValveTop Entry Ball ValveTriple Duty ValveTriple Eccentric Butterfly ValveTriple Offset Butterfly ValveTrunnion Ball ValveTwin Seal Plug ValveUL/FM Approved ValvesUnidirectional Knife Gate ValveWafer Butterfly ValveWater Pressure Reducing ValveY StrainerY Type Globe ValveZirconium Floating Ball ValveZirconium Gate ValveZirconium Globe ValveZirconium Valves

1 Piece Ball Valve1 Piece Cast Iron Screwed Ball Valve1 Piece Flanged Ball Valve1 Piece Screwed Ball Valve2 Piece Ball valve2 Piece Cast Steel Ball Valve2 Piece Flanged Ball Valve2 Piece Forged Steel Ball Valve2 Piece Screwed Ball Valve3 Piece Ball Valve3 Piece Cast Iron Ball Valve3 Piece Cast Steel Ball Valve3 Piece Flanged Ball Valve3 Piece Forged Steel Ball Valve3 Piece Reduced Port Ball Valve3 Piece Screwed Ball Valve3 Way Converging and Diverging Control Valve3 Way Plug Valve3 Way Pneumatic Diaphragm Control ValveAir ValveAlloy 20 2 Piece Ball ValveAlloy 20 2 Piece Screwed Ball ValveAlloy 20 3 Piece Ball ValveAlloy 20 3 Piece Screwed Ball ValveAlloy 20 Ball ValveAlloy 20 Dual Plate Lug Type Check ValveAlloy 20 Floating Ball ValveAlloy 20 Swing Check ValveAlloy 20 Trunnion Mounted Ball ValveAlloy 20 ValvesAlloy 20 Wafer Butterfly ValveAlloy Butterfly ValveAlloy Check valveAlloy Dual Plate Wafer Check ValveAlloy Flanged Gate ValveAlloy Flanged Globe ValveAlloy Gate ValveAlloy Gate ValvesAlloy Globe ValvesAlloy Lug Butterfly ValveAlloy Plug ValveAlloy Pressure Seal Globe ValveAluminium Bronze 3 Piece Ball ValveAluminium Bronze Ball ValveAluminium Bronze Butterfly ValveAluminium Bronze Check ValveAluminium Bronze Floating Ball ValveAluminium Bronze Gate ValveAluminium Bronze Lug Butterfly ValveAluminium Bronze Swing Check ValveAluminium Bronze Triple offset Lug Butterfly ValveAluminium Bronze Trunnion Ball ValveAluminium Bronze valvesAluminium Bronze Wafer Butterfly ValveAluminium Dual Plate Wafer Check ValveAluminum Bronze Globe ValveAngle Globe ValveANSI Gate ValveANSI Globe ValveAPI Aluminium Bronze Triple offset Lug Butterfly ValveAPI Gate ValveAPI Globe ValveAustenitic Steel Big Size Ball ValveAustenitic Steel ValvesAWWA Butterfly ValveAWWA Gate ValveAWWA Non Rising Stem Gate ValveAWWA OS&Y Gate ValveAWWA StrainerAWWA Wafer Butterfly ValveAWWA Y StrainerBalancing ValveBall Float Steam TrapBall ValveBellow Seal Globe ValveBi Directional Knife Gate ValveBimetallic Steam TrapBlock and Bleed valveBrass Ball ValveBrass Ball ValvesBrass Check ValvesBrass Flanged Ball ValveBrass Flanged Gate ValveBrass Flanged Globe ValveBrass Gate ValveBrass Gate ValvesBrass Globe ValveBrass Globe ValvesBrass Safety ValveBrass Swing Check ValveBrass ValveBrass Vertical Check ValveBrass Y StrainerBronze Butterfly ValveBronze Check ValveBronze Flanged Gate ValveBronze Flanged Globe ValveBronze Floating Ball ValveBronze Gate ValveBronze Gate ValvesBronze Globe ValveBronze Globe ValvesBronze Swing Check ValveBronze ValveBronze Wafer Butterfly ValveBronze Wafer Check ValveBS Cast Iron Gate valveBS Cast Steel Gate ValveBS Ductile Iron Gate ValveBS Globe ValveBS Non Rising Stem Gate ValveBS NRS Carbon Steel Gate ValveBS NRS Cast Iron Gate ValveBS NRS Ductile Iron Gate ValveBS Rising Stem Gate ValveBS Soft Seat Gate ValveBS Stainless Steel Gate ValveButterfly ValveCarbon Steel Bellow Seal Globe ValveCast Floating Ball ValveCast Iron And Cast Steel Ball ValveCast Iron Diaphragm ValveCasting Trunnion Ball Valvecheck valveConnection Lift Plug ValveControl ValveCryogenic Ball ValveCryogenic Check ValveCryogenic Emergency Cut off ValveCryogenic Gate ValveCryogenic Globe ValveCryogenic Long Stem Globe ValveCryogenic Pneumatic Actuated Globe ValveCryogenic Short Stem Globe ValveCryogenic Steam Jacket Globe ValveCryogenic ValveDiaphragm ValveDIN Globe ValveDIN Non Rising Stem Ductile Iron Gate ValveDIN Non Rising Stem Gate ValveDIN NRS Cast Iron Gate ValveDIN Rising Stem Cast Iron Gate ValveDIN Rising Stem Ductile Iron Gate ValveDIN Rising Stem Gate ValveDIN Soft Seat Gate ValveDirect Acting Pressure Reducing ValveDouble Block and Bleed Ball ValveDouble Disc Gate ValveDouble Eccentric Butterfly ValveDouble Offset Butterfly ValveDouble Orifice Air Release ValveDouble Orifice Kinetic Air ValveDual Plate Lug Check ValveDual Plate Wafer Check ValveDuctile Iron Diaphragm ValveDuplex 1B 3 PC Ball ValveDuplex 3 Piece Ball ValveDuplex Basket StrainerDuplex Butterfly ValveDuplex Check ValveDuplex Dual Plate Lug Type Check ValveDuplex Dual Plate Wafer Check ValveDuplex Floating Ball ValveDuplex Gate ValveDuplex Globe ValveDuplex High Pressure Ball ValveDuplex Lug Type Butterfly ValveDuplex Steel Ball ValveDuplex steel ValveDuplex Swing Check ValveDuplex Top Entry Ball ValveDuplex Trunnion Mounted Ball ValveDuplex Wafer Butterfly ValveEccentric Plug ValveElectric 3 Way Control ValveElectric Actuated 2 Piece Ball ValveElectric Actuated 2 Piece Flanged Ball ValveElectric Actuated 2 Piece Screwed Ball ValveElectric Actuated Ball ValveElectric Actuated Butterfly ValveElectric Actuated Flanged Ball ValveElectric Actuated Floating Forged Ball ValveElectric Actuated Gate ValveElectric Actuated Globe Control ValveElectric Actuated Globe ValveElectric Actuated High Pressure Ball ValvesElectric Actuated High Pressure Direct Mounting Ball ValvesElectric Actuated Lug Butterfly ValveElectric Actuated Metal-Seated Trunnion-Mounted Forged Ball ValveElectric Actuated Three Piece Ball ValveElectric Actuated Three Way Ball ValveElectric Actuated Trunnion-Mounted Casting Ball ValveElectric Actuated ValvesElectric Actuated Wafer Butterfly ValveElectric Cage Type Control ValveElectric Control ValveElectric Double Seat Control ValveElectric O-type Shut-off Control ValveElectric Single Seat Control ValveF22/Alloy Steel Pressure Seal Globe ValveF317L Gate ValveF317L Globe ValveF317L ValvesF321 Gate ValveF321 Globe ValveF321 ValvesF347 3 Piece Ball ValveF347 Ball ValveF347 Butterfly ValveF347 Check ValveF347 Dual Plate Lug Type Check ValveF347 Dual Plate Wafer Check ValveF347 Floating Ball ValveF347 Gate ValveF347 Globe ValveF347 Lug Type Butterfly ValveF347 Swing Check ValveF347 Trunnion Mounted Ball ValveF347 ValvesF347 Wafer Butterfly ValveF44 Gate ValveF44 Globe valvesF44 ValvesF51 Super Duplex Ball ValveF53/F55 Super Duplex Globe ValveFeed Water Control ValveFlanged Butterfly ValveFlanged Knife gate ValveFloat Control ValveFloating Ball ValveFluorine Lined Single Seat Control ValveFoot ValveForged Cryogenic Trunnion Ball ValveForged Floating Ball ValveForged Steel Ball ValveForged Steel Gate ValveForged Steel Globe ValveForged Steel Swing Check ValveForged Trunnion Ball ValveFull Lift Pressure Safety ValveFull Lift Safety ValveFully Welded Ball ValveGate ValveGlobe ValveHastelloy Ball ValveHastelloy C276 2 Piece Flanged Ball ValveHastelloy C276 2 Piece Screwed Ball ValveHastelloy C276 3 Piece Screwed Ball ValveHastelloy C276/B3 3 Piece Ball ValveHastelloy C276/B3 Butterfly ValveHastelloy C276/B3 Dual Plate Lug Type Check ValveHastelloy C276/B3 Dual Plate Wafer Check ValveHastelloy C276/B3 Floating Ball ValveHastelloy C276/B3 Gate ValvesHastelloy C276/B3 Globe ValveHastelloy C276/B3 Lug Butterfly ValveHastelloy C276/B3 Swing Check valveHastelloy C276/B3 Trunnion Mounted Ball ValveHastelloy C276/B3 ValvesHastelloy C276/B3 Wafer Butterfly ValveHastelloy Check ValveHeavy Duty Investment Casting Ball ValveHigh Performance Lug Butterfly ValveHigh Performance Wafer Butterfly ValveIncoloy 2 Piece Ball ValveIncoloy 3 Piece Ball ValveIncoloy Gate ValveIncoloy Globe ValveIncoloy ValvesInconel 2 Piece Ball ValveInconel 3 Piece Ball ValveInconel Ball ValveInconel Butterfly ValveInconel Check ValveInconel Dual Plate Lug Type Check ValveInconel Dual Plate Wafer Check ValveInconel Floating Ball ValveInconel Gate ValveInconel Globe ValveInconel Lug Butterfly ValveInconel safety relief valveInconel Swing Check ValveInconel Trunnion Mounted Ball ValveInconel ValveInconel Wafer Butterfly ValveInverted Bucket Steam TrapInvestment Casting Ball ValveJacketed Ball ValveJacketed Plug ValveKnife Gate ValveLift Check valveLow Lift Pressure Safety ValveLow Lift Safety ValveLubricated Plug valveLug Butterfly ValveMonel 2 Piece Ball ValveMonel 3 Piece Ball ValveMonel 400 2 Piece Flanged Ball ValveMonel 400 ValvesMonel Ball ValveMonel Butterfly ValveMonel Check ValveMonel Dual Plate Lug Check ValveMonel Dual Plate Wafer Check ValveMonel Floating Ball ValveMonel Forged Trunnion Mounted Ball ValveMonel Gate ValveMonel Globe ValveMonel High Pressure Ball ValveMonel Lug Type Butterfly ValveMonel Swing Check ValveMonel Top Entry Ball ValveMonel Trunnion Mounted Ball ValveMonel ValvesMonel Wafer Butterfly ValveNeedle valveNon Slam Swing Check ValveNon-Lubricated Sleeved Plug ValveNon-Rising Stem Gate ValveNon-Slam Swing Check ValveOrbit Plug ValvePilot Operated Pressure Reducing ValvePilot Operated ValvePressure Relief ValvePiston ValvePlug ValvePlunger ValvePneumatic Actuated 2 Piece Ball ValvePneumatic Actuated 2 Piece Flanged Ball ValvePneumatic Actuated Ball ValvePneumatic Actuated Butterfly ValvePneumatic Actuated Flanged Ball ValvePneumatic Actuated Flanged Butterfly ValvePneumatic Actuated Gate ValvePneumatic Actuated Globe type Control ValvePneumatic Actuated Lug Butterfly ValvePneumatic Actuated Three Piece Ball valvePneumatic Actuated Three Way Ball valvePneumatic Actuated Three Way Heavy Duty Ball ValvePneumatic Actuated Two Piece Ball ValvePneumatic Actuated ValvesPneumatic Actuated Wafer Butterfly ValvePneumatic Angle Control ValvePneumatic Angle Seat Control ValvePneumatic Angle Type High Pressure Regulating Control ValvePneumatic Bi Directional Knife Gate valvePneumatic Cage Control ValvePneumatic Control ValvePneumatic Double Seat Control ValvePneumatic Flow Control ValvePneumatic Knife Gate ValvePneumatic Metal Seat Flanged Ball ValvePneumatic Single Seat Globe Control ValvePneumatic Sleeve Type Control ValvePneumatic Three piece Ball ValvePneumatic Three Piece Flanged Ball ValvePneumatic Three Way Ball ValvePneumatic Three Way Flanged Ball ValvePneumatic Trunnion Casting Ball ValvePneumatic Trunnion Forged Ball ValvePneumatic Trunnion Forged Metal Seat Ball ValvePneumatic Unidirectional Knife Gate ValvePressure Reducing ValvePressure Safety ValvePressure Seal Gate ValvePressure Seal Globe ValvePressure Seal Swing Check ValveRotary Airlock ValveSafety ValveSimplex Basket StrainersSingle Orifice Air ValveSingle Plate Wafer Check ValveSlab Gate ValveSlurry Knife Gate ValveSoft Seal Gate ValveSpeciality ValveSS304 Bellow Seal Globe ValveSS316 Bellow Seal Globe ValveSS316L Gate ValveSS316L Lug Butterfly ValveSS316L Wafer Butterfly ValveSteam Pressure Reducing ValveSteam Safety ValveSteam TrapStrainersSuction DiffuserSuper Duplex 2 Piece Ball ValveSuper Duplex 3 Piece Ball ValveSuper Duplex 5A Flanged Gate ValveSuper Duplex 5A Globe ValveSuper Duplex 5A Swing Check ValveSuper Duplex Ball ValveSuper Duplex Butterfly ValveSuper Duplex Check ValveSuper Duplex Dual Plate Lug Type Check ValveSuper Duplex Dual Plate Wafer Check ValveSuper Duplex Floating Ball ValveSuper Duplex Gate ValveSuper Duplex Gate ValvesSuper Duplex Globe ValveSuper Duplex High Pressure Ball ValveSuper Duplex Knife Gate ValveSuper Duplex Lug Butterfly ValveSuper Duplex Pressure Reducing ValveSuper Duplex Top Entry Ball ValveSuper Duplex Trunnion Mounted Ball ValveSuper Duplex ValvesSuper Duplex Wafer Butterfly ValveSurge Anticipator ValveSwing Check ValveThermal Safety ValveThermodynamic Steam TrapThermostatic Steam TrapThree Piece Flanged Ball ValveThree Way Ball ValveThrough Conduit Knife Gate ValveTilting Disc Check ValveTitanium 3 Piece Ball ValveTitanium Ball ValveTitanium Butterfly ValveTitanium Check ValveTitanium Dual Plate Lug Type Check ValveTitanium Dual Plate Wafer Check ValveTitanium Floating Ball ValveTitanium Forged Trunnion Mounted Ball ValveTitanium Gate ValveTitanium Globe ValveTitanium Gr.2 2pc Flanged Ball ValveTitanium Gr.2 3pc Ball ValveTitanium Gr.5 2pc Flanged Ball ValveTitanium Gr.5 3pc Ball ValveTitanium Lug Butterfly ValveTitanium Swing Check ValveTitanium Trunnion Mounted Ball ValveTitanium valvesTitanium Wafer Butterfly ValveTop Entry Ball ValveTriple Duty ValveTriple Eccentric Butterfly ValveTriple Offset Butterfly ValveTrunnion Ball ValveTwin Seal Plug ValveUL/FM Approved ValvesUnidirectional Knife Gate ValveWafer Butterfly ValveWater Pressure Reducing ValveY StrainerY Type Globe ValveZirconium Floating Ball ValveZirconium Gate ValveZirconium Globe ValveZirconium Valves

Flange Full Lift Safety Valves can be used on systems where the discharge is relatively simple. The pressure in the discharge system can be atmospheric, at a constant level or where the pressure may build up to a maximum of 10% of the set pressure. When a constant back...

Thread Full Lift Safety Valves can be used on systems where the discharge is relatively simple. The pressure in the discharge system can be atmospheric, at a constant level or where the pressure may build up to a maximum of 10% of the set pressure. When a constant back...

We"re professional full lift safety valve manufacturers and suppliers in China, supplying the best industrial valves. Feel free to buy high quality full lift safety valve made in China here from our factory.

... -start valve with Series MX2 air treatment units without the need for additional connection interfaces. The soft-start valve is positioned upstream of the safety valves, ...

Two hands safety valve, which allows a safety use of two hands pneumatic controls (for example two push-button 3/2 N.C. to a certain distance) excluding false signals in case of push-button ...

The SI2 safety valve prevents the allowed operating pressure from being exceeded by more than 10%. If, after opening, the adjusted response pressure falls ...

... stainless steel full-lift clean service safety valve designed to AD Merkblatt A2 and TRD 421 standards and suitable for pure steam, vapour and inert gases.

Insert style flow control valves are comprised of a precision orifice in parallel with a check valve, combined into a single component. Each is designed for easy installation into metal housings using ...

Press-in style flow control valves are comprised of a precision flow orifice in parallel with a check valve, combined into a single component. Each part is designed for easy installation into plastic ...

If you have been searching for a safety release valve that you can use to reduce short-term pressure surges successfully and diminish the effects of gas leaks, this is the product for you. With a pe of ...

... have been type tested as well. These pressure regulators have safety valves which will slam shut in the event of emergencies, such as the gas reaching too high a pressure level. The valve ...

This product has hydraulically actuated class A gas safety valves to EN 161 used for automatic shut-off. It shuts off when unstimulated for gas and air, or even biologically produced methane. It has AISi ...

The S 104 Safety Shut Off valve is mainly used to avoid any damage to components as well as to avoid too high or too low pressure in the gas train. This could cause high financial losses and/or injured ...

The S50 Safety Shut Off valve is mainly used to avoid any damage to components as well as to avoid too high or too low pressure in the gas train. This could cause high financial losses and/or injured ...

The S100 Safety Shut Off valve is mainly used to avoid any damage to components as well as to avoid too high or too low pressure in the gas train. This could cause high financial losses and/or injured ...

... Pressure Safety Valve + Rupture Disk is protected and may be utilized autonomously as essential security gadgets or in conjunction. There are 3 possible combinations. The first combinations ...

Excavator pipe-rupture valves prevent uncontrolled cylinder movement in the event that a pipe or hose bursts. The ESV valve fulfills all of the requirements of the ISO 8643 and EN 474-5 standards for ...

Material: Body- CF8M; Valve Seat- CF8M Métal Seat, PTFE Soft Seat available Orifice Size: fc"(15mm), 3/4M(20mm), l"(25mm), l1/4,’(32mm)I ltë”(40mm), ...

The Safety valves from ATOS are designed to guarantee protection for application on various devices, especially those that monitor spool position. They are also recommended for hydraulic ...

The primary purpose of a safety valve is to protect life, property and the environment. Safety valves are designed to open and release excess pressure from vessels or equipment and then close again.

The function of safety valves differs depending on the load or main type of the valve. The main types of safety valves are spring-loaded, weight-loaded and controlled safety valves.

Regardless of the type or load, safety valves are set to a specific set pressure at which the medium is discharged in a controlled manner, thus preventing overpressure of the equipment. In dependence of several parameters such as the contained medium, the set pressure is individual for each safety application.

Curtiss-Wright"s selection of Pressure Relief Valves comes from its outstanding product brands Farris and Target Rock. We endeavor to support the whole life cycle of a facility and continuously provide custom products and technologies. Boasting a reputation for producing high quality, durable products, our collection of Pressure Relief Valves is guaranteed to provide effective and reliable pressure relief.

While some basic components and activations in relieving pressure may differ between the specific types of relief valves, each aims to be 100% effective in keeping your equipment running safely. Our current range includes numerous valve types, from flanged to spring-loaded, threaded to wireless, pilot operated, and much more.

A pressure relief valve is a type of safety valve designed to control the pressure in a vessel. It protects the system and keeps the people operating the device safely in an overpressure event or equipment failure.

A pressure relief valve is designed to withstand a maximum allowable working pressure (MAWP). Once an overpressure event occurs in the system, the pressure relief valve detects pressure beyond its design"s specified capability. The pressure relief valve would then discharge the pressurized fluid or gas to flow from an auxiliary passage out of the system.

Below is an example of one of our pilot operated pressure relief valves in action; the cutaway demonstrates when high pressure is released from the system.

Air pressure relief valves can be applied to a variety of environments and equipment. Pressure relief valves are a safety valve used to keep equipment and the operators safe too. They"re instrumental in applications where proper pressure levels are vital for correct and safe operation. Such as oil and gas, power generation like central heating systems, and multi-phase applications in refining and chemical processing.

At Curtiss-Wright, we provide a range of different pressure relief valves based on two primary operations – spring-loaded and pilot operated. Spring-loaded valves can either be conventional spring-loaded or balanced spring-loaded.

Spring-loaded valves are programmed to open and close via a spring mechanism. They open when the pressure reaches an unacceptable level to release the material inside the vessel. It closes automatically when the pressure is released, and it returns to an average operating level. Spring-loaded safety valves rely on the closing force applied by a spring onto the main seating area. They can also be controlled in numerous ways, such as a remote, control panel, and computer program.

Pilot-operated relief valves operate by combining the primary relieving device (main valve) with self-actuated auxiliary pressure relief valves, also known as the pilot control. This pilot control dictates the opening and closing of the main valve and responds to system pressure. System pressure is fed from the inlet into and through the pilot control and ultimately into the main valve"s dome. In normal operating conditions, system pressure will prevent the main valve from opening.

The valves allow media to flow from an auxiliary passage and out of the system once absolute pressure is reached, whether it is a maximum or minimum level.

When the pressure is below the maximum amount, the pressure differential is slightly positive on the piston"s dome size, which keeps the main valve in the closed position. When system pressure rises and reaches the set point, the pilot will cut off flow to the dome, causing depressurization in the piston"s dome side. The pressure differential has reversed, and the piston will rise, opening the main valve, relieving pressure.

When the process pressure decreases to a specific pressure, the pilot closes, the dome is repressurized, and the main valve closes. The main difference between spring-loaded PRVs and pilot-operated is that a pilot-operated safety valve uses pressure to keep the valve closed.

Pilot-operated relief valves are controlled by hand and are typically opened often through a wheel or similar component. The user opens the valve when the gauge signifies that the system pressure is at an unsafe level; once the valve has opened and the pressure has been released, the operator can shut it by hand again.

Increasing pressure helps to maintain the pilot"s seal. Once the setpoint has been reached, the valve opens. This reduces leakage and fugitive emissions.

At set pressure the valve snaps to full lift. This can be quite violent on large pipes with significant pressure. The pressure has to drop below the set pressure in order for the piston to reseat.

The pilot is designed to open gradually, so that less of the system fluid is lost during each relief event. The piston lifts in proportion to the overpressure.

At Curtiss-Wright we also provide solutions for pressure relief valve monitoring. Historically, pressure relief valves have been difficult or impossible to monitor. Our SmartPRV features a 2600 Series pressure relief valve accessorized with a wireless position monitor that alerts plant operators during an overpressure event, including the time and duration.

There are many causes of overpressure, but the most common ones are typically blocked discharge in the system, gas blowby, and fire. Even proper inspection and maintenance will not eliminate the occurrence of leakages. An air pressure relief valve is the only way to ensure a safe environment for the device, its surroundings, and operators.

A PRV and PSV are interchangeable, but there is a difference between the two valves. A pressure release valve gradually opens when experiencing pressure, whereas a pressure safety valve opens suddenly when the pressure hits a certain level of over pressurization. Safety valves can be used manually and are typically used for a permanent shutdown. Air pressure relief valves are used for operational requirements, and they gently release the pressure before it hits the maximum high-pressure point and circulates it back into the system.

Pressure relief valves should be subject to an annual test, one per year. The operator is responsible for carrying out the test, which should be done using an air compressor. It’s imperative to ensure pressure relief valves maintain their effectiveness over time and are checked for signs of corrosion and loss of functionality. Air pressure relief valves should also be checked before their installation, after each fire event, and regularly as decided by the operators.

Direct-acting solenoid valves have a direct connection with the opening and closing armature, whereas pilot-operated valves use of the process fluid to assist in piloting the operation of the valve.

A control valve works by varying the rate of fluid passing through the valve itself. As the valve stem moves, it alters the size of the passage and increases, decreases or holds steady the flow. The opening and closing of the valve is altered whenever the controlled process parameter does not reach the set point.

Control valves are usually at floor level or easily accessible via platforms. They are also located on the same equipment or pipeline as the measurement and downstream or flow measurements.

An industrial relief valve is designed to control or limit surges of pressure in a system, most often in fluid or compressed air system valves. It does so as a form of protection for the system and defending against instrument or equipment failure. They are usually present in clean water industries.

A PRV is often referred to as a pressure relief valve, which is also known as a PSV or pressure safety valve. They are used interchangeably throughout the industry depending on company standards.

China Spring Loaded Full Lift Safety Valve Manufacturer Shinjo Supplies A48H Spring Loaded Full Lift Safety Valve, 150-900LB, PN16-PN100, ASME, API 526.

Safety valves are an arrangement or mechanism to release a substance from the concerned system in the event of pressure or temperature exceeding a particular preset limit. The systems in the context may be boilers, steam boilers, pressure vessels or other related systems. As per the mechanical arrangement, this one get fitted into the bigger picture (part of the bigger arrangement) called as PSV or PRV that is pressure safety or pressure relief valves.

This type of safety mechanism was largely implemented to counter the problem of accidental explosion of steam boilers. Initiated in the working of a steam digester, there were many methodologies that were then accommodated during the phase of the industrial revolution. And since then this safety mechanism has come a long way and now accommodates various other aspects.

These aspects like applications, performance criteria, ranges, nation based standards (countries like United States, European Union, Japan, South Korea provide different standards) etc. manage to differentiate or categorize this safety valve segment. So, there can be many different ways in which these safety valves get differentiated but a common range of bifurcation is as follows:

The American Society of Mechanical Engineers (ASME) I tap is a type of safety valve which opens with respect to 3% and 4% of pressure (ASME code for pressure vessel applications) while ASME VIII valve opens at 10% over pressure and closes at 7%. Lift safety valves get further classified as low-lift and full lift. The flow control valves regulate the pressure or flow of a fluid whereas a balanced valve is used to minimize the effects induced by pressure on operating characteristics of the valve in context.

A power operated valve is a type of pressure relief valve is which an external power source is also used to relieve the pressure. A proportional-relief valve gets opened in a relatively stable manner as compared to increasing pressure. There are 2 types of direct-loaded safety valves, first being diaphragms and second: bellows. diaphragms are valves which spring for the protection of effects of the liquid membrane while bellows provide an arrangement where the parts of rotating elements and sources get protected from the effects of the liquid via bellows.

In a master valve, the operation and even the initiation is controlled by the fluid which gets discharged via a pilot valve. Now coming to the bigger picture, the pressure safety valves based segment gets classified as follows:

So all in all, pressure safety valves, pressure relief valves, relief valves, pilot-operated relief valves, low pressure safety valves, vacuum pressure safety valves etc. complete the range of safety measures in boilers and related devices.

Safety valves have different discharge capacities. These capacities are based on the geometrical area of the body seat upstream and downstream of the valve. Flow diameter is the minimum geometrical diameter upstream and downstream of the body seat.

The nominal size designation refers to the inlet orifice diameter. A safety Valve"s theoretical flowing capacity is the mass flow through an orifice with the same cross-sectional area as the valve"s flow area. This capacity does not account for the flow losses caused by the valve. The actual capacity is measured, and the certified flow capacity is the actual flow capacity reduced by 10%.

A safety valve"s discharge capacity is dependent on the set pressure and position in a system. Once the set pressure is calculated, the discharge capacity must be determined. Safety valves may be oversized or undersized depending on the flow throughput and/or the valve"s set pressure.

The actual discharge capacity of a safety valve depends on the type of discharge system used. In liquid service, safety valves are generally automatic and direct-pressure actuated.

A safety valve is used to protect against overpressure in a fluid system. Its design allows for a lift in the disc, indicating that the valve is about to open. When the inlet pressure rises above the set pressure, the guide moves to the open position, and media flows to the outlet via the pilot tube. Once the inlet pressure falls below the set pressure, the main valve closes and prevents overpressure. There are five criteria for selecting a safety valve.

The first and most basic requirement of a safety valve is its ability to safely control the flow of gas. Hence, the valve must be able to control the flow of gas and water. The valve should be able to withstand the high pressures of the system. This is because the gas or steam coming from the boiler will be condensed and fill the pipe. The steam will then wet the safety valve seat.

The other major requirement for safety valves is their ability to prevent pressure buildup. They prevent overpressure conditions by allowing liquid or gas to escape. Safety valves are used in many different applications. Gas and steam lines, for example, can prevent catastrophic damage to the plant. They are also known as safety relief valves. During an emergency, a safety valve will open automatically and discharge gas or liquid pressure from a pressurized system, preventing it from reaching dangerous levels.

The discharge capacity of a safety valve is based on its orifice area, set pressure, and position in the system. A safety valve"s discharge capacity should be calculated based on the maximum flow through its inlet and outlet orifice areas. Its nominal size is often determined by manufacturer specifications.

Its discharge capacity is the maximum flow through the valve that it can relieve, based on the maximum flow through each individual flow path or combined flow path. The discharge pressure of the safety valve should be more than the operating pressure of the system. As a thumb rule, the relief pressure should be 10% above the working pressure of the system.

It is important to choose the discharge capacity of a safety valve based on the inlet and output piping sizes. Ideally, the discharge capacity should be equal to or greater than the maximum output of the system. A safety valve should also be installed vertically and into a clean fitting. While installing a valve, it is important to use a proper wrench for installation. The discharge piping should slope downward to drain any condensate.

The discharge capacity of a safety valve is measured in a few different ways. The first is the test pressure. This gauge pressure is the pressure at which the valve opens, while the second is the pressure at which it re-closes. Both are measured in a test stand under controlled conditions. A safety valve with a test pressure of 10,000 psi is rated at 10,000 psi (as per ASME PTC25.3).

The discharge capacity of a safety valve should be large enough to dissipate a large volume of pressure. A small valve may be adequate for a smaller system, but a larger one could cause an explosion. In a large-scale manufacturing plant, safety valves are critical for the safety of personnel and equipment. Choosing the right valve size for a particular system is essential to its efficiency.

Before you use a safety valve, you need to know its discharge capacity. Here are some steps you need to follow to calculate the discharge capacity of a safety valve.

To check the discharge capacity of a safety valve, the safety valve should be installed in the appropriate location. Its inlet and outlet pipework should be thoroughly cleaned before installation. It is important to avoid excessive use of PTFE tape and to ensure that the installation is solid. The safety valve should not be exposed to vibration or undue stress. When mounting a safety valve, it should be installed vertically and with the test lever at the top. The inlet connection of the safety valve should be attached to the vessel or pipeline with the shortest length of pipe. It must not be interrupted by any isolation valve. The pressure loss at the inlet of a safety valve should not exceed 3% of the set pressure.

The sizing of a safety valve depends on the amount of fluid it is required to control. The rated discharge capacity is a function of the safety valve"s orifice area, set pressure, and position in the system. Using the manufacturer"s specifications for orifice area and nominal size of the valve, the capacity of a safety valve can be determined. The discharge flow can be calculated using the maximum flow through the valve or the combined flows of several paths. When sizing a safety valve, it"s necessary to consider both its theoretical and actual discharge capacity. Ideally, the discharge capacity will be equal to the minimum area.

To determine the correct set pressure for a safety valve, consider the following criteria. It must be less than the MAAP of the system. Set pressure of 5% greater than the MAAP will result in an overpressure of 10%. If the set pressure is higher than the MAAP, the safety valve will not close. The MAAP must never exceed the set pressure. A set pressure that is too high will result in a poor shutoff after discharge. Depending on the type of valve, a backpressure variation of 10% to 15% of the set pressure cannot be handled by a conventional valve.

Direct Loaded Safety Valves for blowing off excess pressure of steam, vapor, gases, and liquid from pressure vessels, steam boiler, hot water boiler and piping systems. ARI-SAFE safety valves are available in full-stroke and normal versions.

Our safety valves are available with metal or soft seated plugs, with precise centering and guiding. Materials include cast iron, cast steel, and stainless steel. Call us for further options!

There is a wide range of safety valves available to meet the many different applications and performance criteria demanded by different industries. Furthermore, national standards define many varying types of safety valve.

The ASME standard I and ASME standard VIII for boiler and pressure vessel applications and the ASME/ANSI PTC 25.3 standard for safety valves and relief valves provide the following definition. These standards set performance characteristics as well as defining the different types of safety valves that are used:

ASME I valve - A safety relief valve conforming to the requirements of Section I of the ASME pressure vessel code for boiler applications which will open within 3% overpressure and close within 4%. It will usually feature two blowdown rings, and is identified by a National Board ‘V’ stamp.

ASME VIII valve- A safety relief valve conforming to the requirements of Section VIII of the ASME pressure vessel code for pressure vessel applications which will open within 10% overpressure and close within 7%. Identified by a National Board ‘UV’ stamp.

Full bore safety valve - A safety valve having no protrusions in the bore, and wherein the valve lifts to an extent sufficient for the minimum area at any section, at or below the seat, to become the controlling orifice.

Conventional safety relief valve -The spring housing is vented to the discharge side, hence operational characteristics are directly affected by changes in the backpressure to the valve.

Balanced safety relief valve -A balanced valve incorporates a means of minimising the effect of backpressure on the operational characteristics of the valve.

Pilot operated pressure relief valve -The major relieving device is combined with, and is controlled by, a self-actuated auxiliary pressure relief device.

Power-actuated safety relief valve - A pressure relief valve in which the major pressure relieving device is combined with, and controlled by, a device requiring an external source of energy.

Standard safety valve - A valve which, following opening, reaches the degree of lift necessary for the mass flowrate to be discharged within a pressure rise of not more than 10%. (The valve is characterised by a pop type action and is sometimes known as high lift).

Full lift (Vollhub) safety valve -A safety valve which, after commencement of lift, opens rapidly within a 5% pressure rise up to the full lift as limited by the design. The amount of lift up to the rapid opening (proportional range) shall not be more than 20%.

Direct loaded safety valve -A safety valve in which the opening force underneath the valve disc is opposed by a closing force such as a spring or a weight.

Proportional safety valve - A safety valve which opens more or less steadily in relation to the increase in pressure. Sudden opening within a 10% lift range will not occur without pressure increase. Following opening within a pressure of not more than 10%, these safety valves achieve the lift necessary for the mass flow to be discharged.

Diaphragm safety valve -A direct loaded safety valve wherein linear moving and rotating elements and springs are protected against the effects of the fluid by a diaphragm

Bellows safety valve - A direct loaded safety valve wherein sliding and (partially or fully) rotating elements and springs are protected against the effects of the fluids by a bellows. The bellows may be of such a design that it compensates for influences of backpressure.

Controlled safety valve - Consists of a main valve and a control device. It also includes direct acting safety valves with supplementary loading in which, until the set pressure is reached, an additional force increases the closing force.

Safety valve - A safety valve which automatically, without the assistance of any energy other than that of the fluid concerned, discharges a quantity of the fluid so as to prevent a predetermined safe pressure being exceeded, and which is designed to re-close and prevent further flow of fluid after normal pressure conditions of service have been restored. Note; the valve can be characterised either by pop action (rapid opening) or by opening in proportion (not necessarily linear) to the increase in pressure over the set pressure.

Direct loaded safety valve -A safety valve in which the loading due to the fluid pressure underneath the valve disc is opposed only by a direct mechanical loading device such as a weight, lever and weight, or a spring.

Assisted safety valve -A safety valve which by means of a powered assistance mechanism, may additionally be lifted at a pressure lower than the set pressure and will, even in the event of a failure of the assistance mechanism, comply with all the requirements for safety valves given in the standard.

Supplementary loaded safety valve - A safety valve that has, until the pressure at the inlet to the safety valve reaches the set pressure, an additional force, which increases the sealing force.

Note; this additional force (supplementary load), which may be provided by means of an extraneous power source, is reliably released when the pressure at the inlet of the safety valve reaches the set pressure. The amount of supplementary loading is so arranged that if such supplementary loading is not released, the safety valve will attain its certified discharge capacity at a pressure not greater than 1.1 times the maximum allowable pressure of the equipment to be protected.

Pilot operated safety valve -A safety valve, the operation of which is initiated and controlled by the fluid discharged from a pilot valve, which is itself, a direct loaded safety valve subject to the requirement of the standard.

The common characteristic shared between the definitions of conventional safety valves in the different standards, is that their operational characteristics are affected by any backpressure in the discharge system. It is important to note that the total backpressure is generated from two components; superimposed backpressure and the built-up backpressure:

Subsequently, in a conventional safety valve, only the superimposed backpressure will affect the opening characteristic and set value, but the combined backpressure will alter the blowdown characteristic and re-seat value.

The ASME/ANSI standard makes the further classification that conventional valves have a spring housing that is vented to the discharge side of the valve. If the spring housing is vented to the atmosphere, any superimposed backpressure will still affect the operational characteristics. Thiscan be seen from Figure 9.2.1, which shows schematic diagrams of valves whose spring housings are vented to the discharge side of the valve and to the atmosphere.

By considering the forces acting on the disc (with area AD), it can be seen that the required opening force (equivalent to the product of inlet pressure (PV) and the nozzle area (AN)) is the sum of the spring force (FS) and the force due to the backpressure (PB) acting on the top and bottom of the disc. In the case of a spring housing vented to the discharge side of the valve (an ASME conventional safety relief valve, see Figure 9.2.1 (a)), the required opening force is:

In both cases, if a significant superimposed backpressure exists, its effects on the set pressure need to be considered when designing a safety valve system.

Once the valve starts to open, the effects of built-up backpressure also have to be taken into account. For a conventional safety valve with the spring housing vented to the discharge side of the valve, see Figure 9.2.1 (a), the effect of built-up backpressure can be determined by considering Equation 9.2.1 and by noting that once the valve starts to open, the inlet pressure is the sum of the set pressure, PS, and the overpressure, PO.

In both cases, if a significant superimposed backpressure exists, its effects on the set pressure need to be considered when designing a safety valve system.

Once the valve starts to open, the effects of built-up backpressure also have to be taken into account. For a conventional safety valve with the spring housing vented to the discharge side of the valve, see Figure 9.2.1 (a), the effect of built-up backpressure can be determined by considering Equation 9.2.1 and by noting that once the valve starts to open, the inlet pressure is the sum of the set pressure, PS, and the overpressure, PO.

Balanced safety valves are those that incorporate a means of eliminating the effects of backpressure. There are two basic designs that can be used to achieve this:

Although there are several variations of the piston valve, they generally consist of a piston type disc whose movement is constrained by a vented guide. The area of the top face of the piston, AP, and the nozzle seat area, AN, are designed to be equal. This means that the effective area of both the top and bottom surfaces of the disc exposed to the backpressure are equal, and therefore any additional forces are balanced. In addition, the spring bonnet is vented such that the top face of the piston is subjected to atmospheric pressure, as shown in Figure 9.2.2.

The bellows arrangement prevents backpressure acting on the upper side of the disc within the area of the bellows. The disc area extending beyond the bellows and the opposing disc area are equal, and so the forces acting on the disc are balanced, and the backpressure has little effect on the valve opening pressure.

Bellows failure is an important concern when using a bellows balanced safety valve, as this may affect the set pressure and capacity of the valve. It is important, therefore, that there is some mechanism for detecting any uncharacteristic fluid flow through the bellows vents. In addition, some bellows balanced safety valves include an auxiliary piston that is used to overcome the effects of backpressure in the case of bellows failure. This type of safety valve is usually only used on critical applications in the oil and petrochemical industries.

Since balanced pressure relief valves are typically more expensive than their unbalanced counterparts, they are commonly only used where high pressure manifolds are unavoidable, or in critical applications where a very precise set pressure or blowdown is required.

This type of safety valve uses the flowing medium itself, through a pilot valve, to apply the closing force on the safety valve disc. The pilot valve is itself a small safety valve.

The diaphragm type is typically only available for low pressure applications and it produces a proportional type action, characteristic of relief valves used in liquid systems. They are therefore of little use in steam systems, consequently, they will not be considered in this text.

The piston type valve consists of a main valve, which uses a piston shaped closing device (or obturator), and an external pilot valve. Figure 9.2.4 shows a diagram of a typical piston type, pilot operated safety valve.

The piston and seating arrangement incorporated in the main valve is designed so that the bottom area of the piston, exposed to the inlet fluid, is less than the area of the top of the piston. As both ends of the piston are exposed to the fluid at the same pressure, this means that under normal system operating conditions, the closing force, resulting from the larger top area, is greater than the inlet force. The resultant downward force therefore holds the piston firmly on its seat.

If the inlet pressure were to rise, the net closing force on the piston also increases, ensuring that a tight shut-off is continually maintained. However, when the inlet pressure reaches the set pressure, the pilot valve will pop open to release the fluid pressure above the piston. With much less fluid pressure acting on the upper surface of the piston, the inlet pressure generates a net upwards force and the piston will leave its seat. This causes the main valve to pop open, allowing the process fluid to be discharged.

When the inlet pressure has been sufficiently reduced, the pilot valve will reclose, preventing the further release of fluid from the top of the piston, thereby re-establishing the net downward force, and causing the piston to reseat.

Pilot operated safety valves offer good overpressure and blowdown performance (a blowdown of 2% is attainable). For this reason, they are used where a narrow margin is required between the set pressure and the system operating pressure. Pilot operated valves are also available in much larger sizes, making them the preferred type of safety valve for larger capacities.

One of the main concerns with pilot operated safety valves is that the small bore, pilot connecting pipes are susceptible to blockage by foreign matter, or due to the collection of condensate in these pipes. This can lead to the failure of the valve, either in the open or closed position, depending on where the blockage occurs.

The terms full lift, high lift and low lift refer to the amount of travel the disc undergoes as it moves from its closed position to the position required to produce the certified discharge capacity, and how this affects the discharge capacity of the valve.

A full lift safety valve is one in which the disc lifts sufficiently, so that the curtain area no longer influences the discharge area. The discharge area, and therefore the capacity of the valve are subsequently determined by the bore area. This occurs when the disc lifts a distance of at least a quarter of the bore diameter. A full lift conventional safety valve is often the best choice for general steam applications.

The disc of a high lift safety valve lifts a distance of at least 1/12th of the bore diameter. This means that the curtain area, and ultimately the position of the disc, determines the discharge area. The discharge capacities of high lift valves tend to be significantly lower than those of full lift valves, and for a given discharge capacity, it is usually possible to select a full lift valve that has a nominal size several times smaller than a corresponding high lift valve, which usually incurs cost advantages.Furthermore, high lift valves tend to be used on compressible fluids where their action is more proportional.

In low lift valves, the disc only lifts a distance of 1/24th of the bore diameter. The discharge area is determined entirely by the position of the disc, and since the disc only lifts a small amount, the capacities tend to be much lower than those of full or high lift valves.

Except when safety valves are discharging, the only parts that are wetted by the process fluid are the inlet tract (nozzle) and the disc. Since safety valves operate infrequently under normal conditions, all other components can be manufactured from standard materials for most applications. There are however several exceptions, in which case, special materials have to be used, these include:

Cast steel -Commonly used on higher pressure valves (up to 40 bar g). Process type valves are usually made from a cast steel body with an austenitic full nozzle type construction.

For all safety valves, it is important that moving parts, particularly the spindle and guides are made from materials that will not easily degrade or corrode. As seats and discs are constantly in contact with the process fluid, they must be able to resist the effects of erosion and corrosion.

The spring is a critical element of the safety valve and must provide reliable performance within the required parameters. Standard safety valves will typically use carbon steel for moderate temperatures. Tungsten steel is used for higher temperature, non-corrosive applications, and stainless steel is used for corrosive or clean steam duty. For sour gas and high temperature applications, often special materials such as monel, hastelloy and ‘inconel’ are used.

Standard safety valves are generally fitted with an easing lever, which enables the valve to be lifted manually in order to ensure that it is operational at pressures in excess of 75% of set pressure. This is usually done as part of routine safety checks, or during maintenance to prevent seizing. The fitting of a lever is usually a requirement of national standards and insurance companies for steam and hot water applications. For example, the ASME Boiler and Pressure Vessel Code states that pressure relief valves must be fitted with a lever if they are to be used on air, water over 60°C, and steam.

A test gag (Figure 9.2.7) may be used to prevent the valve from opening at the set pressure during hydraulic testing when commissioning a system. Once tested, the gag screw is removed and replaced with a short blanking plug before the valve is placed in service.

The amount of fluid depends on the particular design of safety valve. If emissio