Seat and Disc
The Solid flat disc and the seats
are made from forged steel.
Both can be ENP coated to prevent
corrosion or galling. Seats can be
provided with a thermoplastic insert
in the face in contact with the disc.
This soft seat insert guarantees
the primary sealing while the metal
contact between disc and seats
guarantees the secondary sealing.
Metal to metal seating design
is available upon request for abrasive
service and for high temperature
design. In this second case,
the seats and the disc are coated
with HVOF Tungsten or Chrome
In normal operating condition,
the slab gate does not need to
be lubricated to maintain a seal.
Sealant can be injected,
as a temporary solution when damage
occurs in the sealing members.
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 or/and with a backseat
between stem and bonnet.
In the event of a gasket failure, this
feature allows restoring of the sealing.
The DBB design is a standard
feature of the Viar Valvole slab gate
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 achived.
Self Relieving Seats
The single piston effect design
of the seats automatically relieves
the body pressure in excess.
In case of fluid thermal expansion and,
generally, when the pressure
in the body cavity exceeds the pressure
in the pipeline, the seat is forced back
into its housing and the pressure
in excess is released between the seat
and the gate into the line.
Full Bore Through
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.
• Material Options (CRA Alloys
for Very Corrosive Service Media)
• Seat and Stem Sealant Injection
• Tungsten Carbide Coated,
Metal to Metal Sealing.
• Compact Design
• Gas Tight, Metal to Metal Sealing
• Corrosion Resistant
• Easy Maintenance
• High Pressure/High Temperature
• Bi-directional Sealing
• Fast Closing
• Fire Safe
• Protection against