Specification

Zero Leakage Direct Buried Flat Plate Gate Valve Two-way Sealing Bevel Gear Transmission Flat Gate Valve

I. Product Overview

NEWWAY zero-leakage direct-buried flat plate gate valves are specially designed for underground pipeline systems, featuring fully sealed buried structures to eliminate space occupation and external damage of surface-mounted valves. Using a flat gate for flow cutoff, the valves adopt ductile iron (GGG50) or cast steel (WCB) bodies with double-layer anti-corrosion coatings, suitable for municipal water supply/drainage, gas, and heating underground pipelines. The innovative anti-settlement sealing structure resists soil displacement, with bidirectional zero-leakage performance certified to API 598, ideal for long-term maintenance-free underground networks.

II. Core Technical Parameters

Nominal Diameter: DN50-DN1200 (2″-48″)

Pressure Class: PN10/PN16/PN25 (1.0MPa/1.6MPa/2.5MPa)

Temperature Range: -20℃~120℃ (heating media), -40℃~60℃ (gas media)

Body Material: Ductile iron GGG50 (tensile strength ≥500MPa), cast steel WCB (tensile strength ≥485MPa)

Sealing System: Metal hard seal (STL overlay) + NBR soft seal, leakage rate ≤0.01% (bubble-tight)

Connection Types: Flanged (GB/T 9113, ASME B16.5), butt-welded (BW)

Protection Grade: IP68 (burial depth ≤6m), anti-soil corrosion compliant with NACE MR0175

Product Overview

III. Structural Design & Technical Features

**Direct-Burial Optimization

Extended stem design (protrusion ≥300mm) with anti-theft ground operation well, preventing well water accumulation.

Three-layer anti-corrosion system (zinc-rich epoxy primer + fiberglass winding + polyurethane topcoat), salt spray test ≥3000h without corrosion.

**Anti-Settlement Sealing Structure

Elastic compensation design between gate and seat allows ±5° axial deflection for uneven soil settlement.

Bellows compensator between bonnet and body absorbs thermal expansion displacement (compensation ≤8mm).

**Low-Torque Operation System

Bevel gear reduction (3:1 ratio) reduces DN300 valve torque from 220N·m to 65N·m.

Trapezoidal thread stem (pitch 6mm) with self-lubricating bronze bushing, operation life ≥10,000 cycles.

IV. Manufacturing Processes & Quality Control

Precision Casting

Ductile iron castings use lost foam process with graphite spheroidization grade ≥2, eliminating shrinkage defects.

Cast steel parts normalized at 920℃ + tempered at 650℃, impact energy ≥34J at -20℃ (Charpy V-notch).

Surface Treatment Technology

Three-layer coating for body anti-corrosion:

Bottom: Zinc-rich epoxy primer (dry film 80μm)

Middle: Fiberglass reinforced layer (1.2mm)

Top: Weather-resistant polyurethane paint (RAL7035, dry film 100μm)

3D Quality Inspection

Pressure test: 1.5x shell strength (30min hold, no deformation), 1.1x sealing test (zero leakage).

Burial simulation: 6m hydrostatic pressure + soil pressure cycling (1000 cycles, no leakage).

NDT: 100% ultrasonic testing (UT), compliant with GB/T 2970 grade III.