DN20 PN160 F11 Alloy Steel Gate Valve with Raised Face Flange Connection and Handwheel Operation

III. Feature Description

• Rising Stem Design: The valve features a rising stem, where the stem moves upward as the valve opens, providing a visual indication of the valve position. This design prevents stem rotation within the packing, reducing wear and ensuring reliable sealing. In high-pressure steam systems, this visibility helps operators confirm valve status, critical for safe operation.

• F11 Alloy Steel Performance: F11 alloy steel offers exceptional high-temperature strength and oxidation resistance, making it suitable for long-term service in environments up to 593℃. Its chromium and molybdenum content enhances corrosion resistance against steam and hydrocarbon media, outperforming carbon steel in high-temperature, high-pressure applications.

• Hardfaced Seats and Gates: The gate and seat surfaces are hardfaced with stellite, a cobalt-chromium alloy, to minimize wear and leakage. This hardfacing withstands the erosive effects of high-velocity media, ensuring tight sealing even after thousands of cycles—vital for high-pressure systems where leakage can lead to energy loss or safety hazards.

• Raised Face Flange Sealing: The raised face flange design, paired with spiral-wound gaskets, creates a metal-to-metal seal under high pressure. This prevents media leakage at the flange connection, even during pressure fluctuations common in power generation and oil & gas pipelines.

• Worm Gear Handwheel: The handwheel is equipped with a worm gear reducer, reducing the torque required to operate the valve under high pressure. This allows for smooth, precise operation, even when the valve is under full PN160 pressure, reducing operator fatigue and ensuring accurate flow control.

• Forging and Heat Treatment: F11 alloy steel billets are forged to form the valve body, gate, and stem, eliminating internal defects and improving material density. Post-forging, components undergo normalizing and tempering (heat treatment at 675-705℃) to enhance toughness and stress resistance, critical for withstanding high pressure and temperature cycles.

• Precision Machining: Key components such as the gate, seat, and stem are machined using CNC equipment to achieve tight tolerances. The gate and seat surfaces are ground to a smooth finish (Ra ≤1.6μm) before hardfacing, ensuring uniform contact and tight sealing. Flange faces are machined to meet ASME B16.5 standards, ensuring compatibility with pipeline flanges.

• Assembly and Packing: The valve is assembled with precision, with the stem guided by bearings to ensure alignment. The packing system uses graphite-based packing rings, which are resistant to high temperatures and provide reliable sealing around the stem. The packing is compressed to prevent leakage without excessive friction, ensuring smooth stem movement.

• Testing: Each valve undergoes rigorous testing, including:

• • Hydrostatic Shell Test: 1.5 times the PN160 rating (24.0MPa) for 30 minutes to verify the body’s structural integrity.

• • Hydrostatic Seat Test: 1.1 times the PN160 rating (17.6MPa) to ensure tight sealing between the gate and seat.

• • Operational Test: Manual operation through full open and close cycles to confirm smooth movement and proper alignment of components.