Butterfly valve – Triple Offset

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TRIPLE OFFSET DESIGN PRINCIPLES

Triple offset metal seat butterfly valve provides a bi-directional and bubble-tight shutoff which is attributed to the geometry of triple offset seat.

The valve stem is offset by seat (1st offset) and the valve seat surface center line is offset against the center line of pipe (2nd offset) and the conical axis is offset by valve center line (3rd offset: inclined cone). The 3rd offset completely eliminates rubbing.

The seat surfaces of body and seal ring in triple offset valve contact with the inclined “cone-in-cone” and this design requires excellent sealing and seat part durability by slight wedging effect.

In addition, the angle of contact between body and seal ring has a good sealing performance by low torque because the angle travels the initial torque from actuator to seat parts without any loss by jamming.

This valve is characteristic of concentric, offset and double offset construction with remarkable sealing performance and seat part durability, and moreover, it is hardly needed to repair.

CHARACTERISTICS AND MERITS

• Excellent durability of seat part and low operating torque by non-rubbing characteristics with triple offset construction.
• Bi-directional zero leakage service by resilient metal sealing and torque seating.
• Unrestricted selection of face to face dimensions for API, ASME(ANSI), BS, ISO, etc. and perfect interchangeability of gate, ball, plug, high performance butterfly, and other VALVE.
• Low emission by quarter turn construction and good performance at automation by virtue of low operating torque and low cost.

DESIGN FEATURE

• Designed in accordance with ASME B 16.34 or other customer requirements.
• Fire safe design.

BODY

• The valve body shall be one piece cast or fabrication.
• The body can be supplied with different types of materials in wafer, lug, or flanged and butt welding end connections to satisfy all installation requirements.

BODY SEAT

• The valve seat shall be integrated with the body.
• Stellite or stainless steel shall be applied on the seating surface of valve body.
• The valve seat is designed for inclined cone to ensure non-rubbing, non-jamming, bi-directional shutoff, and zero leakage.

DISC

• The valve disc shall be the same material as the valve body. It is supported by laminated seal ring, which is kept in place by seat retainer ring bolted to the disc and can be replaced easily.
• The spiral wound gasket shall be provided between laminated seal ring and disc.

SEAL RING (LAMINATED)

• The seal ring shall be resilient stainless steel lamella alternated by graphite, aramid fiber & cermic fiber layers.
• The surface contacting between seal ring and body seat is an inclined cone type and the inclined angle generates a slight wedging effect.
• With a seat retainer ring bolted to the disc, the seal ring is fixed to disc not too tightly to be replaced easily.

STEM

• The stem shall be stainless steel and one piece & two pieces construction.
• The stem shall be fixed to the disc by pin or in combination of pin and key.It can be protected by internal thrust bush and bush bearing.
• The thrust bush and bush bearing shall be provided to locate the valve disc in a proper position.
• The retainer ring shall be installed to avoid blowing out the stem.

PACKING

• The packing shall be consist of two braided rings in the top and bottom of valve and three die formed graphite rings in the middle.
• The lantern ring may be provided as required by customer.

ACTUATORS

• All valve shall be self-locking manual gear operation type which is served as standard.
• Electric, pneumatic or hydraulic actuator may be provided as required by customer.