Válvulas industriais conforme normas API · ASME · DIN · EN
Válvulas de Segurança Operadas por Piloto
As válvulas de segurança operadas por piloto combinam uma válvula principal com um piloto externo: o piloto sente a pressão da linha e controla a válvula principal, dando abertura total na pressão de ajuste com blowdown curto enquanto permanece dinamicamente estanque abaixo dela — de modo que a pressão de operação pode rodar próxima à pressão de ajuste sem simmer ou perda de meio. A cobertura típica de classe vai de DN25-DN200 (1" x 2" a 8" x 10" entrada x saída) em ANSI Classe 150-600 / PN16-PN100 em corpos WCB, CF8 ou CF8M; a janela de pressão de ajuste é confirmada frente à capacidade exigida e à seleção do piloto no RFQ. Os pilotos são de ação pop ou modulante e selecionáveis em campo; os tipos modulantes toleram contrapressão superimposta maior. Terminais flangeados (RF). A arquitetura do piloto é o que compra as margens: com área de dome maior que a área do assento a válvula principal permanece estanque até dentro de 5% da pressão de ajuste (98% de estanqueidade do assento) onde válvulas de mola já simmer, pilotos de ação pop abrem a cerca de 1% de sobrepresão e reassentam a 97% (ajustável a 85%, blowdown -3% a -15%), pilotos modulantes acompanham a demanda e alcançam abertura total a 110% do ajuste, e contrapressão até 70% — excepcionalmente 95% — é compensada com um dispositivo antirretorno. O modo de falha determinante é a linha de sensibilidade do piloto: meios com partículas ou cristalizantes entopem seu furo de ~10 mm (mantenha a válvula em serviço limpo, atente a coque e polimerização), e uma rampa rápida de partida pode desbalancear o dome e simular uma abertura. A instalação mantém a tomada remota com área equivalente de 3/8 de polegada até 100 pés sem válvula de bloqueio na linha de suprimento, e a conexão de teste de campo permite teste funcional em serviço. ASME VIII UG-126(b) exige o piloto autoacionado e a válvula principal em falha aberta à capacidade total. A seleção depende da razão operação-versus-ajuste, da contrapressão, do meio e da ação do piloto.
Faz parte da Válvulas de Segurança família
Última atualização: 2026-11
Especificações da família
| Pressure class / nominal rating designation | ANSI Class 150-600 / PN16-PN100 |
|---|---|
| Nominal valve connection size | DN25-DN200 (1in x 2in - 8in x 10in inlet x outlet) |
| Valve body material | WCB, CF8, CF8M |
| End connection types | flange (RF) |
| Service temperature range | -162 to 320°C |
| pilot type | pop-action or modulating; field-selectable |
| design note | main valve + external pilot; full-lift at set pressure with short blowdown |
| operating pressure ratio vs spring limit | Spring-loaded valves struggle to close completely above roughly 90% of set pressure; the pilot-operated main valve closes with a dome area larger than the seat area so closing force exceeds opening force, letting system operating pressure run within 5% of set pressure without increased seat leakage - the standard choice for high operating-to-set ratios |
| pop action reseat and adjustable blowdown | Pop-action pilot: opens at about 1% overpressure, closes at 97% of set pressure adjustable down to 85%, with blowdown adjustable between -3% and -15% above the API standard; modulated-closure pilots hold blowdown to max 7% |
| modulating vs pop pilot principle | Pop-action fully empties the main-valve dome for snap full lift; in modulate action the dome is only partially emptied, with the extent of emptying determined by the inlet pressure, so the main valve modulates with the relief demand |
| modulating partial opening capacity control | Modulating diaphragm-pilot execution: the valve opens further as process pressure rises and reaches full lift at 110% of set (High Gain option by 105%); the pilot is the nonflowing type - with the main valve relieving at steady pressure, no process fluid flows through the pilot |
| back pressure tolerance | Pilot actuation is differential, so back-pressure tolerance is high: pilot-operated safety valves can consistently compensate 70% back pressure and in certain cases run at a 95% back-pressure ratio; operability stays unaffected up to 70% of set pressure provided a backflow preventer is used whenever back pressure can exceed inlet pressure |
| seat tightness high operating ratio | Pilot-operated SRVs can achieve seat tightness up to 98% of set pressure for both the main valve and the pilot valve - the basis for running close to set pressure without simmer |
| posv definition | A pilot-operated safety relief valve is a pressure relief valve in which the major relieving device (main valve) is combined with and controlled by a self-actuated auxiliary pressure relief valve called a pilot valve |
| asme ug 126b pilot requirements | ASME Code Sec. VIII UG-126(b) permits pilot-operated pressure relief valves provided the pilot is self-actuated and the main valve opens automatically at not over set pressure and discharges full rated capacity even if some essential part of the pilot fails - the fail-open requirement |
| pilot blowdown short adjustment | The pilot portion of some pilot-operated valves can be set at blowdowns as short as 2% - far tighter than direct-spring pop valves |
| sensing line blockage failure mode | The pilot sensing (pressure-tap) line is the governing failure mode: media containing particles or prone to crystallization can plug the roughly ten-millimeter line, after which the safety valve can no longer perform its intended function; pilot-operated valves are supplied with filters and generally recommended for relatively clean service |
| dirty service limits | Pilot-operated valves should not be employed in abrasive or dirty service, where coking, polymerization or corrosion of wetted pilot parts can occur, or where the lading fluid can freeze or condense at ambient temperature; for severe dirty service where interconnecting tubing can clog, a pilot-operated SRV might not be the best fit |
| rapid pressure ramp false lift | During plant start-up with an extremely rapid system-pressure ramp rate, the dome area may not equalize with the same inlet pressure, resulting in insufficient closing force - a pilot-operated-specific false-lift mode |
| soft seal and temperature limits pilot | Pilot soft seals (O-rings) bound the application envelope: at temperatures of 200 °C and above the safety valve manufacturer should be consulted |
| sensing line remote pickup sizing rules | Installation rule for remote pressure pickup: piping must have the equivalent flow area of 3/8 in tubing for lengths up to 100 feet, longer runs require factory consultation; a block valve in the remote pilot supply line is not recommended and, if used, must be opened before pressurizing the main valve |
| field test connection in service | A field test connection allows operators to functionally test the pilot-operated SRV while it remains in service - a maintenance advantage over direct spring valves that must be pulled for bench testing |
| oem maintenance resources posv toolbox | OEM maintenance reference: the valve manufacturer publishes a dedicated maintenance toolbox for pilot-operated types 811 (pop action) and 821 (modulating) with repair guidance to the manufacturer quality standards |
| set pressure range example diaphragm pilot | OEM example envelope (pilot-operated relief valve with diaphragm pilot): set pressure range 15 psig to 740 psig; reseat pressure defined as the supply pressure where the dome pressure increases to 75% of supply pressure - an industry-reference anchor, not a tenant supply claim |
| Source 1 — orifice area range | effective orifice areas of 0.128 through 45.664 inches |
| Source 1 — inlet size range | valve inlet sizes 1-inch through 8-inch |
| Source 1 — Set-pressure range | set pressures from 15 to 3,705 psig (1 to 260 barg) |
| Source 1 — continuous temperature range | Continuous service temperatures from -50°F to +450°F |
| Source 1 — nonflowing pilot principle | with the non-flowing pilot provides highly reliable system overpressure protection |
| Source 1 — dirty service pilot design | The pilot is a non-flowing design minimizing the entry of dirt and the accumulation of hydrates |
| Source 1 — pilot supply filtration | Inline tubing external filter is also available |
| Source 1 — vertical pilot mounting | Consistent set pressure and blowdown are assured compared to horizontally mounted pilots that are erratic |
| Source 1 — orifice nozzle replacement | The orifice size may be changed by replacing a single component |
| Source 1 — external blowdown adjustment | Adjustable blowdown is external, reducing time and cost-consuming expenditures of valve removal |
| Source 1 — replaceable soft seat | With a replaceable soft seat, expensive parts and time-consuming lapping of metal seats are no longer necessary |
| Source 1 — asme capacity verification | capacity is assured by an independent third party, the ASME National Board Laboratory in Columbus, Ohio |
| Source 1 — operating ratio capability | The valve can be set within 5% of system operating pressure allowing the process to be maintained at close tolerance without valve leakage |
| Source 1 — typical applications | for Gas Compressors, Pressure Vessels, Cold Box Storage, Meter Runs, Gas Plants, Pipelines, and Transmission Stations |
| Source 2 — low pressure vacuum protection | provide safe, dependable, and accurate low pressure and/or vacuum protection |
| Source 2 — api2000 sealing | Seals in accordance with API 2000 requirements for Pilot Operated Relief Valves |
| Source 2 — rated flow overpressure | Rated flow at 10% overpressure provides the ability to operate closer to the tank MAWP, increasing the operating range of the process |
| Source 2 — seat action flexibility | Flexibility in terms of film or o-ring seat and snap or modulating action allows product customization to specific application requirements |
| Source 2 — vacuum breaker variant | The Model 1662A incorporates a vacuum breaker. |
| Source 2 — Nominal valve connection size | Sizes: 2” through 12” (50-300mm) |
| Source 2 — pressure settings | Pressure Settings: from 7.0* InWC to 15 psig |
| Source 2 — vacuum settings | Vacuum Settings: 7.0 InWC to 12 psig |
| Source 2 — standard body materials | Standard Body Materials: Carbon Steel (WCB/CS), Stainless Steel (CF8M/316), Aluminum (356) |
| Source 2 — supply media temperature range | Supply Media Temperature Range: -320° F to 300° F |
| Source 2 — drilling classes | 150# ANSI, PN10, PN16, JIS drilling classes available |
| Source 2 — pilot accessories | Pilot exhaust piped to discharge header, Field test connection, Manual blow down, Conical film seat pallet, Remote sense pickup, Pilot supply filter |
| Source 3 — Nominal valve connection size | Size 1/2” to 20” |
| Source 3 — Pressure Rating | Pressure Rating 150# x 150# to 2500# x 300# |
| Source 3 — End connection types | End Connection Flange End, Screwed End, Tri-Clover End |
| Source 3 — seat options | Seat Metal Seat / Soft Seat |
| Source 3 — orifice standard | Orifice As per API 520 |
| Source 3 — blowdown and overpressure | Blow Down <10% of Set Pressure, Over Pressure >10% of Set Pressure |
| Source 3 — Valve body material | Material Carbon steel, Stainless steel, Duplex-SS, nickel-molybdenum alloy, Alloy-20, nickel-copper alloy |
| Source 3 — pilot sensing design | Design - High Pressure, Semi- Nozzle/ Full- Nozzle, Piston Sensing Pilot |
| Source 3 — type options | Type Conventional, Balanced Bellow, Balance Piston, Pilot Operated, PTFE Lined |
| Source 4 — seat design options | Soft seat design: Provides repeatable bubble-tight performance before and after each relief cycle, Metal-to-metal seat design: Provides pilot valve performance in high temperature service |
| Source 4 — balanced design principle | Balanced design: Lift unaffected by back pressure; no expensive and fragile bellows required to balance against high back pressure |
| Source 4 — full lift dot maop capability | Full lift at set pressure: No overpressure required for full lift; allows D.O.T. installation to be set higher than Maximum Allowable Operating Pressure (MAOP) when pop action is used |
| Source 4 — replaceable seats and seals | Replaceable soft seats and seals: All seats and seals are renewable easily and quickly; no expensive, time-consuming seat lapping required |
| Source 4 — api526 center to face dimensions | API 526 direct spring center-to-face dimensions available for Series 200, 400, 500 and 800 pilots eliminating the need for piping modifications during upgrades |
| Source 4 — pop action cryogenic benefit | Pop action available: No main valve throttling, which helps prevent freeze-ups in cryogenic or refrigerant type services |
| Source 4 — modulating action benefits | Modulating action available: Significantly cut product loss per relief situation; reduce environmental pollution; avoid oversizing consequences; not as sensitive to inlet pressure losses as pop action |
Notas de âmbito e fontes
| back pressure capability tension | Back-pressure capability tension: the page spec states superimposed back pressure up to ~50% of set, while OEM documents state 70% consistent compensation (LESER, 95% in certain cases; Crosby 70% with backflow preventer); the ~50% figure should be owner-reviewed against per-configuration OEM limits. |
|---|---|
| pilot closure figures | Generic vendor pages describe pilot closure near 90% of set pressure; OEM pop-action figures are 97% (adjustable to 85%, blowdown -3% to -15%) - the OEM figures govern; generic-website numbers were excluded from this page. |
| set pressure envelope | Emerson Series 400 shows a 15-740 psig (about 1-51 barg) set-pressure envelope, so the page 0.1-10 MPa range is a tenant selection, not an industry ceiling; temperature envelope (-162 to 320 °C) sits against soft-seal limits where the manufacturer must be consulted at 200 °C and above - quote per configuration. |
Encomenda e documentação
Documentos
Solicite com o pedido o conjunto documental de que precisa — os itens habituais para esta execução (certificados de material, relatórios de ensaio segundo a norma de inspeção indicada, desenhos dimensionais) são confirmados e fornecidos com a cotação.
Cotação
Um pedido pronto para cotação indica: dimensão nominal e classe de pressão, preferência de materiais do corpo e da sede, ligação terminal, acionamento, e o fluido de serviço com a sua temperatura. Os valores típicos nesta página são gamas de referência; os valores vinculativos são confirmados na cotação.
Amostra e fornecimento
As condições de fornecimento, quantidades encomendadas e prazos são acordados por encomenda — indique o país de destino e o calendário requerido com o pedido.
Armazenamento e expedição
Armazene as válvulas com sedes e vedantes protegidos de UV, ozono e deformação, mantenha as proteções das faces de junção até à instalação e, nas execuções com sede em elastómero ou PTFE, evite o armazenamento prolongado ao ar livre — os compostos das sedes envelhecem mais depressa à luz solar direta e em condições de congelamento.
Perguntas frequentes
O que uma solicitação de cotação para válvulas de segurança operadas por piloto deve incluir?
A norma e a classe aplicáveis, o tamanho nominal, os materiais do corpo e do assento, o meio de serviço com temperatura e o destino — o que estiver faltando é confirmado durante a cotação.
Que tamanho e classe de pressão estão disponíveis em válvulas de segurança operadas por piloto?
Uma faixa de tamanho e classe de pressão verificada para esta válvula ainda não está publicada nesta página — o tamanho e classe de pressão aplicável à sua aplicação é proposto e confirmado durante a cotação. Envie as condições de serviço com a consulta; a seleção é indicada na proposta.
Que material do corpo estão disponíveis em válvulas de segurança operadas por piloto?
Uma faixa de material do corpo verificada para esta válvula ainda não está publicada nesta página — o material do corpo aplicável à sua aplicação é proposto e confirmado durante a cotação. Envie as condições de serviço com a consulta; a seleção é indicada na proposta.
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