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Gate Valves


Double Expanding

Gate Valves




How Does It Work
 The Expanding Gate Valve achieves its sealability by mechanically expanding the 2-piece obturator assembly (gate and segment) against the seats. The gate is attached and driven by the stem and a centralizer mechanism retain the gate segment assembly during the open and closing travel. The valve must be torqued fully open or fully closed to seal properly. This design prevents damage to the sealing surfaces of the gate and seat and isolates the body cavity preventing buildup of foreign material, increasing the life of the valve.
Fully Closed
In the full expanded closed position, the segment has engaged the lower stop and the gate is wedged downward, expanding the gate and segment against the upstream and downstream seats forming a tight mechanical seal.
Mid Position
During open and closing travel, the gate-segment assembly the gate travels across the wedge angle of the segment. The centralizer mechanism allows the gate and segment assembly to travel freely without sticking or wedging preventing relative movement between the gate and segment.
Fully Open
In the full expanded open position, the segment has engaged the upper stop and the gate is wedged upward expanding the segment and the gate into the seats sealing against both seats. This protects the seat faces from line flow, while isolating the body cavity from the flow bore.

Seat and Disc
The 2-piece obturator and the seats are manufactured from forged steel. Both are HVOF Tungsten or Chrome carbide coated. Sealant can be injected, as a temporary solution when damage occurs in the sealing members.

Stem Design and Seal System
The valve is engineered with rising stem. The standard stem seal is with braided graphite and can be fitted with an emergency grease injection device. In the event of a gasket failure, this feature allows restoring of the sealing.

Double Block and Bleed
The DBB design is a standard feature of the Viar Valvole double expanding gate valve . When the valve is in fully closed position, pressure and or fluid in body-bonnet cavity can be released through the body drain system. In the same position, a double isolation between the two sides of the valve is achieved.

Relieving Device
Expanding Gate Valve design will trap pressure in the valve body cavity when the valve is in the full open or closed position. To protect the valve from overpressure, in case of fluid thermal expansion and, generally, when pressure in the body cavity exceeds the pipeline pressure, the valve can be provided with upstream relief piping/valve which relieves excess body pressure in excess to the upstream side.

Full Bore Through Conduit
The pressure drop is minimized without any turbulence. The valve is Piggable: Pigs and scrapers can be run through the valve without damages to the valve.

Optional Features
• Material Options (CRA Alloys for Very Corrosive Service Media)
• Seat & Stem Sealant Injection System
• Actuation

Benefits
• Gas Tight, Metal to Metal Sealing
• Corrosion Resistant
• Easy Maintenance
• High Pressure / High Temperature
• Bi-directional Sealing
• Fast Closing • Fire Safe.


Company

COMPANY HISTORY

100% Italian Family Owned.

EQUIPMENTS

Grant flexibility and reliability.

ASSEMBLY & DELIVERY

Granting Fast Track deliveries

QUALITY

Control & Assurance.

DESIGN

Simulation of every structural aspect.

SPECIAL TEST

In addition to API6D standard tests.

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Brochure Gate
uni iso 9001 - 2008
TA-LUFT ORING GRAPHITE
TA-LUFT GRAPHITE
SIL 3 TRUNNION
SIL 3 FLOATING
RTN
Quality management certificate
PED Quality assurance certificate
ATEX
BP OHSAS 18001-2
BS OHSAS 18001
Certificate of API 6A monogram
Certificate of API 6D monogram
Certificate of API 6DSS monogram
GOST R-1
GOST R-2
GOST R-3