RT Valves - Triple Offset Butterfly Valves

CONSTRUCTION DETAILS

Body
The body geometry is designed as the result of stress calculations according to current engineering standard and rules. The body material is high quality steel. The seats surface is covered by a wear resistance stainless steel deposited by welding overlay. On request the seat surface can be covered also with stellite or other special material overlays. The body desing ca be wafer or lug or flanged or butt welding ends type.

Disc
The disc is designed to reduce at the minimum possible the pressure drop and the cavitation effects. In full open position the disc is rotated by 90° in respect of full close position. The disc seat is made with a metallic and graphoil composite gasket that can be replaced. This sealing don’t contain PTFE, rubber or other plastic components that can be susceptible to high temperatures limiting the use of the valve only in the allowable range for the body material. The triple offset design of the disc seats permits a friction free operation and a superior tightness performance without the need of a resilient seat. This feature guarantees a long life of the seat with reduced maintenance. This full metal construction of the seat make the valve inherently fire safe then the ideal choice to handle flammable fluids.

Shaft
The shaft is one piece and full length type permitting to use the valve also for high differential pressure. Different shaft materials are available for all kind of applications or service condition. The shaft is supported by two long length bearings that reduce the torque and increase the reliability. To avoid any leakage the stem has a high finish degree and
a strict diametrical clearance. The torque is transmitted from the stem to the disc means two or more keys to assure a high resistance to static and dynamic force.

Gasket
The standard gaskets used for sealing are in pure graphite stainless steel reinforced. This type of gasket is suitable for many different applications. For special applications (cryogenic gases, high corrosion acids etc.) RT can supply special gaskets designed for the specific application or according to customer specifications.

Stem
In all outside screw valves the stem is provided with integral backseat for emergency leak repairing. The stem is produced whit special turning machinery for a high resistance and durability. The stem thread is metric type according to ISO standard with trapezoidal section. The tread is left hand type in the way that the valve opens rotating clockwise the handwheel.

Packing
The standard packing is made of four or more pure graphite rings with square section with anti-extrusion system. Other materials like PTFE are available on request.

Bracket
The standard valves are provided bracket with ISO 5211 connection suitable to apply on the valve a quarter turn gearbox or an actuators. On request RT can provide a full range of gearbox already assembled on the valve suitable for all service conditions. One or more keys transmit the torque from the operator to the stem.