3/4″-800LB-SW Bellows Seal Gate Valve

Nominal Size 3/4 inch (DN 20)
Pressure Class Class 800LB (equivalent to PN 140 ~ 160 bar, depending on standard)
End Connection Socket Weld (SW)
Structure Type Outside Screw & Yoke (OS&Y) / Solid Wedge
Stem Sealing Bellows seal + auxiliary graphite packing

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Technical Data Sheet

Product: Bellows Seal Gate Valve
Model / Size: 3/4″ – 800LB – SW

Product Description

This valve adopts a bellows seal design, which fundamentally eliminates stem packing leakage commonly found in conventional gate valves. The bellows assembly, combined with the stem, forms a static seal. An additional packing box serves as a secondary backup seal, achieving a “zero leakage” stem sealing performance. It is suitable for severe service conditions including high temperature, high pressure, high vacuum, and toxic, flammable, or corrosive media.

Basic Parameters

Item	매개변수
공칭 크기	3/4 inch (DN 20)
Pressure Class	Class 800LB (equivalent to PN 140 ~ 160 bar, depending on standard)
End Connection	Socket Weld (SW)
Structure Type	Outside Screw & Yoke (OS&Y) / Solid Wedge
Stem Sealing	Bellows seal + auxiliary graphite packing

설계 표준

Item	기준
Design & Manufacture	API 602 (Steel Gate, Globe and Check Valves for Petroleum and Natural Gas Industries – Compact Design)
Pressure-Temperature Rating	ASME B16.34
End Connection (SW)	ASME B16.11
Face-to-Face Dimension	ASME B16.10 / Manufacturer’s standard
Inspection & Testing	API 598 (or ISO 5208)
Bellows Testing	ISO 15848-1 (Fugitive Emissions Standard)

Bill of Materials (Typical Configuration)

Part Name	Material (Typical Options)	비고
몸	A105 / A182 F316	Carbon steel / Stainless steel optional
Wedge	A105 + 13Cr / F316	13Cr or Stellite hardfacing on sealing faces
Seat Ring	Integral per API 602	Stellite 6 hardfacing on body seat
줄기	A182 F6a / F316	Precipitation hardened stainless / Austenitic SS
Bellows Assembly	SS304 / SS316L	Multi-ply formed, high cycle life
Bonnet	A105 / A182 F316	Matching body material
Packing	Flexible Graphite	With corrosion inhibitor
Handwheel / Stem Nut	Carbon steel (or ductile iron) / Copper alloy

Dimensions & Weight (Reference)

Item	Value
Face-to-Face (L)	Approx. 117 mm (per API 602)
Handwheel Diameter (W)	Approx. 100 mm
Overall Height (H)	Approx. 240 mm
Socket Weld Bore (D)	Per ASME B16.11, socket depth approx. 10 mm
Approx. Weight	5.5 ~ 7.5 kg (depending on material)

Operating Conditions

Item	매개변수
Suitable Media	Steam, thermal oil, toxic gases/liquids, corrosive media, hydrocarbons
Temperature Range (Carbon Steel)	-29°C ~ 425°C
Temperature Range (Stainless Steel)	-196°C ~ 538°C (cryogenic / high temperature)
Max. Allowable Pressure	Per ASME B16.34, Class 800LB at ambient temperature (38°C) approx. 13.8 MPa (138 bar)

Testing & Inspection

Shell Strength Test: 1.5 times rated pressure, no leakage.
High-Pressure Seat Test: 1.1 times rated pressure.
Low-Pressure Pneumatic Test: 0.6 MPa compressed air.
Bellows Leak Test: Helium mass spectrometry, leakage rate < 1×10⁻⁶ Pa·m³/s (or meeting Class V sealing requirement).
Operational Test: Valve cycled fully open/close under rated differential pressure.

Features & Benefits

Zero Leakage Assurance: The bellows isolates the stem from the atmosphere, eliminating external stem leakage – ideal for stringent environmental applications.
Long Service Life: High-cycle-life bellows design ensures reliability under frequent operation.
Low Maintenance: Dual stem sealing (bellows + packing) provides a secondary seal in the event of bellows failure, ensuring system safety.
High Temperature & Pressure Capability: Class 800 rating with socket weld ends is suitable for high-pressure steam and thermal oil systems.

Notes:

Dimensions and weights are typical values based on API 602; actual values may vary slightly depending on manufacturer design (e.g., handwheel size, bonnet height).
For NACE MR0175 (sour service) compliance, please specify when ordering.
During installation, follow the approved Welding Procedure Specification (WPS) for socket weld connections to avoid welding stress that could affect bellows life.

보증:

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