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平行滑動閘閥

平行滑動閘閥以位置密封：彈簧將兩個平行閉合件壓合以在低壓下落座，之後管線壓力上升將它們推向閥座，密封隨介質壓力增大而加緊——這種自增強密封針對蒸汽、給水等高壓高溫用途。產品範圍涵蓋 NPS 2" 至 88"（DN50 至 DN2200），Class 300 至 4500（PN25 至 PN760），閥體為碳鋼、合金鋼與雙相不鏽鋼，端接為 RF、BW 或 RTJ，操作為手動、氣動、電動或液動。此設計帶來三項具體優勢：平行閘板在平面上滑動，不會像楔形閘板在熱停機後被夾死那樣發生熱咬合，因此頻繁熱循環的高溫蒸汽管線正是為了消除該失效模式而選用此型式；無楔緊作用，操作扭矩保持低位，便於執行器選型；在高壓等級下壓力自緊閥蓋與管線壓力同樣強化閥座密封——密封力隨壓差增長，而閘板彈簧或內部撐開件設定實際的低壓差密封極限。它嚴格而言是開關型截斷閥：半開狀態會沖蝕平面閥座並引發閘板高頻抖動，因此流量控制需另配調節閥，而雜物滯留或管路變形造成的閥座失準會使閘板無法貼合——最終關閉前應沖洗管線並保持管路對中。維護對車間友好：無需專用工具即可拆解、更換閘板彈簧、研磨或修復閥座面、保持填料壓蓋壓緊度、為閥桿螺紋上脂，並定期活動閥門以免沉積物堆積在常開或常關的閥座上。垂直淨空允許位置指示有意義時選明桿，受限或地下安裝選暗桿。密封性依 API 598（殼體、關斷、後座）驗證，歐洲框架為 ISO 5208 / EN 12266-1；API 600 管轄螺栓閥蓋製程截斷閥，而 API 6D 增加管線專屬任務，包括防火測試、酸性服務、循環操作與 API 600 框架不要求的閥體腔壓自動洩放。選型取決於壓力等級對蒸汽條件、閥體合金對介質，以及端接對管路規格的匹配。

屬於閘閥系列

最後更新： 2026-11

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系列規格

Nominal valve connection size	NPS 2"~88"(DN50~DN2200)
Pressure class / nominal rating designation	Class 300~4500（PN25~PN760）
Pressure class / nominal rating designation	300~4500（PN25~PN760）
Valve body material	Carbon steel, Alloy steel, Duplex stainless steel
End connection types	RF, BW, RTJ
Operation / closure mode	Manual, Pneumatic, Electric, Hydraulic
applications	High pressure and high temperature services such as steam and feedwater
selection thermal binding elimination vs wedge	Parallel slide gate valves avoid thermal binding because the two discs slide parallel to flat seats instead of being forced between inclined seats, so body contraction during shutdown cannot wedge the closure member tight. This makes the design the usual choice for high-temperature steam lines that undergo frequent thermal cycles.
selection pressure assisted sealing low deltap basis	Sealing force comes from line pressure acting on the downstream disc, so seat tightness improves as differential pressure rises. At low pressure the disc springs or internal spreaders alone provide the baseline seat contact, which sets the practical low-differential-pressure sealing limit of the design.
selection no wedging seizure and torque	Because the discs do not wedge, opening and closing torque stays low and there is no wedging action to seize the valve after thermal expansion. This reduces actuator sizing and lowers seat wear over repeated operating cycles.
selection pressure seal bonnet self energizing	For high-pressure classes the bonnet is typically of pressure-seal type: internal pressure forces the gasket more tightly into its seat, so bonnet sealing improves as pressure rises. This matches the self-reinforcing behavior of the parallel-disc seat seal.
selection hp steam water isolation positioning	The parallel slide gate valve is an established valve type for high-pressure steam and high-pressure water isolation duty, offered in ratings from ANSI 150 to ANSI 1500 with tight shut-off obtained from line pressure rather than mechanical wedging.
selection catalog size class envelope example	A typical commercial parallel slide gate valve envelope runs from small sizes up to DN900, in ANSI class 150 to 600 with flanged or butt-welded ends. Wider class ranges are offered by power-plant specialists, so class availability must be confirmed per manufacturer.
failure throttling chatter seat erosion	Parallel slide gate valves are on-off isolation devices only. Holding the valve partially open for throttling produces turbulence across the nearly closed flat seats, eroding the seat faces and driving high-frequency disc chatter, so a separate regulating valve is required where flow control is needed.
failure trapped solids seat leakage	The flat, closely finished parallel seats are vulnerable to debris: suspended solids trapped between the faces hold the discs off the seat and cause leakage, and piping loads that distort the seats have the same effect. Line flushing before final closure and correct piping alignment are the preventive measures.
failure thermal binding wedge mechanism contrast	Thermal binding, the classic wedge-gate failure after a hot shutdown, occurs when the cooling body contracts and clamps the wedge between the seats, seizing the valve or buckling the stem. The parallel-disc design is selected precisely to remove this failure mode from high-temperature service.
installation routine maintenance and exercise	Routine care consists of checking gland packing compression, lubricating the stem threads, and periodically cycling (exercising) the valve so deposits cannot build up on the seats and disc edges - an important regime for valves that normally stand open or closed for long periods.
installation seat refurbishment workshop tooling	The valve can be disassembled for inspection without special equipment: seat faces can be examined, internal disc springs replaced, and sealing surfaces restored with standard workshop tooling, which keeps lapping or seat refurbishment practical in normal maintenance.
installation stem choice vs vertical clearance	Rising-stem versions give clear visual open/closed position indication but need vertical space above the valve; non-rising-stem versions keep the stem height fixed and suit confined installations such as underground vaults and cramped pipe racks, at the cost of less obvious position indication.
standards api598 closure testing reference	Seat (closure) tightness for steel gate valves of this family is generally proven per API 598 as referenced by the valve specification, with shell, closure and, where fitted, backseat tests. ISO 5208 / EN 12266-1 rate classes are the equivalent European acceptance frame.
standards api600 vs api6d scope	API 600 governs bolted-bonnet steel gate valves for refinery and process isolation, while API 6D is the pipeline-valve standard covering gate valves for transportation systems and adds pipeline-specific requirements such as fire testing, sour service and operational cycling. Project specifications may require one or both.
standards api6d cavity pressure relief	Where a gate valve is built to API 6D for pipeline service, the body cavity must be able to relieve trapped overpressure automatically in addition to the normal shell and seat tests - a requirement not present in basic API 600 process-isolation valves.
peer size range severe service psg	4 – 36"
peer pressure class severe service psg	ASME / ANSI Class 150 – 4500
peer body materials severe service psg	Carbon steel (A216 WCB) – standard Alloy steel (A217 WC9, A217 C12A) – standard Stainless steel (A351 CF8M) – standard
peer compliance nuclear silver psg	ASME B16.34 PED Nuclear ASME III Class 1, 2 and 3 Nuclear Safety Related – 10CFR50 Appendix B SIL
peer end connection default psg	Buttweld – standard Other end connections available upon request
psg bidirectional zero leakage shutoff	Bi-directional, zero-leakage shutoff
psg disc seat carbide overlay	The valve discs and seats have been overlaid with the same carbide overlay (68-70 RC)
psg seat lapping vacuum tight	and are lapped to achieve a bubble-tight seal under all pressure conditions, including vacuum.
psg web guide parallel discs	The web guide (which is also carbide overlayed) ensures the discs are kept parallel, whether the valve is in the open or closed position.
psg wear honing not galling	As the valve is cycled under differential pressure, the extremely hard surfaces continually hone and polish each other instead of scratching and galling.
psg pressure seal bonnet graphite composite	The pressure seal bonnet has been designed with a graphite composite seal.
psg bonnet bolting cold preload	The bonnet has sufficient mechanical bolting to ensure the seal does not relax during periods when the system is not pressurized.
psg stem gland hardfaced polished	The stem and gland are hardfaced and polished.
psg backseat chrome carbide	The back seat is coated with chrome carbide (typical hardness 68-70 RC) and polished to achieve a bubble tight seal.
peer size range double disc psg	NPS 2 1/2 to 24 DN 65 to 600
peer pressure class double disc psg	150 to 1500 PN 25 to 260
peer seating material double disc psg	Seating Material: Metal
double disc design service envelope	this exclusive disk and wedge design resists effects of extreme temperatures, gross thermal transients, high and low differential pressures, and dual-phase fluids.
double disc bonnet internal access	Increased plant and personnel safety is made possible by bonnet design, allowing easy access to valve internals while minimizing radiation exposure
peer standards nuclear double disc psg	ASME B16.34 ASME Section III
peer actuation configs double disc psg	Motor Actuated Motor Operator Hydraulic Actuated Hydraulic Operator
psg disc cooldown no stress	There is no mechanical stress exerted between the discs or problems associated with the cooldown of the fluid.
sealing principle	Positional seal, Line pressure as sealing force
special features	Spring between the two closure members provides an initial seal during low pressure conditions, Higher medium pressure creates the primary seal, the higher the medium pressure the better the sealing performance

範圍與來源備註

type level parameters	A Chinese vendor page under the same English name lists Flexible/Solid Wedge materials and 1.0-2.5 MPa water/sewage duty, while OEM references position the parallel slide type as high-pressure steam/water isolation up to ANSI 1500 - the vendor page appears to describe a low-pressure slide-gate family; its parameters are product-specific, not type-level.
sealing direction framing differs by construction	Sealing-direction framing differs by construction: one source characterizes API 600 gate valves as unidirectional sealing relying on bolted-bonnet pre-load, while parallel-slide references describe line-pressure-assisted bidirectional sealing - the framings reflect different gate constructions under the standards, not one sealing rule.
temperature range	Temperature envelope differs materially between catalog sources (-196 to 593 C on one catalog versus -29 to 425 C on another); the tenant entry quotes no single type-level envelope and per-material limits must be confirmed per manufacturer.