Forged steel butt-welded gate valve is a valve connected to pipeline systems via welding, with key components including the valve body, gate, stem, and sealing assembly. The valve body is typically made of high-temperature-resistant materials such as stainless steel or alloy steel to ensure structural stability under elevated temperatures. The gate is designed to move up and down within the valve body, enabling flow channel opening or closing. When the stem rotates, it drives the gate to rise or fall, controlling fluid flow. The sealing assembly utilizes high-temperature-resistant materials (e.g., graphite or metal seals) to prevent leakage.
This valve operates simply yet efficiently. In the closed position, the gate fully blocks the flow channel, creating a tight seal; when open, the gate lifts, allowing smooth fluid passage. The butt-welded connection ensures a robust bond between the valve and pipeline, minimizing leakage risks-making it particularly suitable for high-temperature and high-pressure applications.
Working Principle
Opening/Closing Operation:
The valve operates by rotating the handwheel or actuator to drive the valve stem, which vertically raises or lowers the gate to achieve full open or full close positions.
Flow Characteristics:
Full Open: The flow channel is straight-through with minimal resistance, ideal for high-flow cutoff applications.
Structural Limitation: The design has a larger overall height and longer opening/closing time compared to other valve types.
Sealing Mechanism:
Metal Hard Seal: The gate and seat are precision-ground, relying on medium pressure to assist sealing.
Elastic Seal: Double gates use spring compensation to maintain sealing performance despite wear.
Core Structure
Valve Body & Bonnet
Valve Body:
Monolithic or split-cast construction, typically made of cast steel (WCB), stainless steel (CF8/CF8M), or alloy steel (WC6).
Butt-Welded Ends: Machined with beveled ends (V or U groove) per GB/T 12224 for pipeline welding.
Bonnet:
Bolted or pressure self-sealing connection to the valve body, incorporating a stuffing box (seals the stem).
Gate & Seat
Gate Types:
Wedge Gate: Single (rigid wedge) or double (elastic wedge), suitable for medium-high pressure.
Parallel Gate: With flow holes or spring-assisted sealing, ideal for particulate-laden media.
Seat: Hardfaced with alloys (e.g., Stellite 6) or made from base material, forming a metal-to-metal seal with the gate.
Stem & Actuation Components
Stem:
Rising Stem (OS&Y): Stem moves visibly with the gate.
Non-Rising Stem: Stem rotates without vertical movement.
Material: Stainless steel (316/17-4PH).
Packing: Flexible graphite, PTFE, or graphite braided rings for high-temperature/pressure resistance.
Butt-Welding Details
Bevel Design: per GB/T 985.1 (e.g., 60°±5° V-groove angle).
Welding Process:
TIG welding for root pass + SMAW for fill passes.
Post-weld heat treatment required for thick-walled valve bodies.
Specification
Gate Valve, API600
Steel Valves, ASME B16.34
Face to face ASME B16.10
End Flanges ASME B16.5/ASME B16.47
Butt Welding ends ASME B16.25
Inspection and test API 598
Operated: Bare Stem
Material: F91
Size Range: 2″~36″
Pressure Rating: ASME CL, 150, 300, 600, 900, 1500, 2500
Temperature Range: -29℃~595℃
Application Scenarios
Oil & Gas Pipelines
Long-distance transmission pipelines as main isolation valves (requiring full-bore design and low flow resistance).
Chemical Plants
High-pressure media isolation at reactor inlet/outlet (hard-sealing + corrosion-resistant materials).
Power Plant Systems
Main steam pipelines (high-temperature/high-pressure conditions, material selection: 12Cr1MoVG).
Liquefied Natural Gas (LNG)
Cryogenic storage & transport systems (deep cryogenic gate valves with extended stem design).
