Through Conduit Double Expanding Gate Valves are manufactured with a full bore port and with 2-piece (gate + segment) obturator designed for a positive, bubble tight shut off upstream and downstream under both low and high differential pressure. Double block and bleed capability and high robustness are standard feature of this seat design. The smooth, continuous bore minimizes turbulence within the valve and when in the open position it produces a pressure drop equivalent to a portion of pipe of same length and diameter.
The seat faces are outside the flow stream and therefore protected from the erosive action of the flow.
Pigs and scrapers can be run through the valve without damage.

PRODUCTION RANGE
Through Conduit (T.C.) Slab Gate Valves are available
in sizes and pressure ratings as follows:
• Class 150# from 2" through 60" • Class 300# from 2" through 60"
• Class 600# from 2" through 60" • Class 900# from 2" through 48"
• Class 1500# from 2" through 42" • Class 2500# from 2" through 24"
APPLICABLE STANDARDS
Through Conduit (T.C.) Slab Gate valves comply with API 6D / API 6D SS and all relevant international codes:
• ASME B16.34 　　 　• ASME B16.25 　　　　• ASME B16.47
• Nace MR01.75 　　　• ASME VIII Div.1

VALVE MATERIALS
Through Conduit Double Expanding Gate valves are manufactured using a wide range of materials, from carbon steel to alloys, in order to comply with all the possible services (Hydrocarbons, Mildly to Highly Corrosive, NACE,etcetera) and applications.ns, Mildly to Highly Corrosive, NACE, etcetera) and applications.

MAIN APPLICATIONS
• Offshore/Onshore applications 　　　　　　　　• Double block and bleed applications　　　　　　 • Sub-sea applications
• Scrapers/Pig Traps/Pig Launchers and Receivers • Oil and gas production/transportation isolation
• Upstream gas compressor isolation　　　　　　　　　　 • Critical and Primary isolation

Expanding gate valve is one kind advanced API 6D design gate valve, provides tight mechanically activaed seal. It has double sealing, bi-directional sealing and enforced mechanical sealing function，and is supplied in full bore fully piggable options .it can be widely used for hot steam.natural gas, oil well drilling system.oilpipeline,and oil tank storage,also can be used for block and shut valve for pipes of chemical flow with acid, alkali corrosive.

CEPAI has two kinds expanding gate valve designs,one is most popular Double Expanding Gate-RDD type, another is Single Expanging Gate valve.

DESIGN FEATURES RDD

◆ Full bore design, easy for run scraper, hot tap cutter and pigs.No flow resistance in the valve port.
◆ Fire safe design to API6FA/API607.
◆ Special top entry design, can be maintained for online condition.
◆ Valve cavity is isolated from the flow both in folly open and fully closed position. Stem packing can be replaced online in fully open and fully closed position after cavity flow released from body vent and drain plug.
◆ Automatically pressure relief system will release the over pressure in the cavity for over pressure, protect the valve.
◆ Can be installed with pipe at any angle, vertical, horizontal, reverse position.
◆ Multi operation types, hand wheel, gear box, pneumatic, electric, etc.
◆ Dust proof plate on yoke.
◆ valve has back seat and stem blow proof design.
◆ Seats may be lubricated to promote long life, minimize.

PRESSURE RELIEF PROVISIONS
The expanding gate valve is one kind enforced bi-directional sealing valve, pressure will be trapped in the valve body cavity when the valve is in the full open or closed position.
High internal pressures can result from the thermal expansion of the fluid trapped in valve cavity,and this over pressure will be released by the body safety relief system to outside valve or to connection pipe.