API 609 Metal Seated Butterfly Valve , Industrial Triple Offset Butterfly Valve

Api 609 Metal Seated Butterfly Valve Cast Steel Triple Offset Industrial Valves


1. Standards

Design and Manufacture; API 609. MSS SP-67, MSS SP-68
Inspection and Test: API S98

End flange dimension: ASME B16 5 (NPS≤24). ASME B16 47 B series
BW end dimension: ASME B16.25

Face to face and end to end; API 609

Pressure-temperature ratings: ASMF B16.34


2. The Seal Principle of Hard Seal Butterfly Valve Triple Offset

The Triple Offset Butterfly Valve provides a bi-directional bubble tight shut-off.This geometry ensures that the disc seal contacts the body seat only at the final shut-off position without rubbing or galling, providing a torque generated resilient seal with sufficient “wedging” to ensure auniform seal contact.


Triple Offset Butterfly Valve Geometry

3. The Triple Offset Geometry
OFFSET 1 The shaft is offset behind the seat axis to allow complete sealing contact around the entire seat

OFFSET2 The shaft centerline is offset from the pipe and valve which provides interference free opening and closing of the valve

0FFSET3 The seat cone axis is offset from the shaft centerline to eliminate friction during closing and opening and to achieve uniform compressive sealing around the entire seat.


4. Friction Free Sealing for Long Cycle Life
(1) Seat is Cr13 Metal alloy or hardfaced with Stellite as standard.

(2) The gasket is spiral wound SS/Graphite for zero leakage.

(3) Seat ring forces are generated by the torque during closing uniformly around the entire circumference. The resilient seal fleses and energizes, assuming the shape of the seat. The compression forces equally distributed around the perimeter provide a tight bi-directional shut off.
The resiliency of the seal allows the valve body and disc to contract or expand, without the risk of jamming due to temperature fluctuations. It is self-adjusting.



Hard Seal (Metal Seated)Butterfly Valve triple offset series are used in such fields as metallurgy, light industry, electric power, petrochemistry, coal gas channel etc.


Triple Offset Butterfly Valve Drawing

6. Materials List (Triple Offset Butterfly Valve)


No. Part Name Materials
1 Body ASTM A216 WCB ASTM A351 CF8 ASTM A351 CF3 ASTM A351 CF8M ASTM A351 CF3M
2 Pin ASTMA29 1035 / A276 304 ASTM A276 304 ASTM A276 304L ASTM A276 316 ASTM A276 316L
3 Stem 420 / 304 / 316 304 304L 316 316L
4 Disc WCB / CF8 / CF8M A351 CF8 A351 CF3 A351 CF8M A351 CF3M
5 Seal Ring 304/316+Graphife / PTFE 304+Grapnite / PTFE 304L+Graphite / PTFE 316+Graphite / PTFE 316L +Graphite / PTFE
6 Retainer Flange A105 / A182 F304 / F316 F304 A182 F304L A182 F316 A182 F316L
7 Bolt B7 / B 8/ B8M B8 B8 B8M B8M
8 Bolt B7 B8 B8 B8M B8M
9 Cover A105 A182 F304 A182 F304L A182 F316 A182 F316L
10 Gasket Graphite Graphite Graphite Graphite Graphite
11 Bushing Luberized bronze 304 Nitriding 304L Nitriding 316 Nitriding 316L Nitriding
12 Bushing 304 Nitriding
13 Packing Seat A105/304 304 304L 316 316L
14 Packing Graphite
16 Packing Cover WCB CF8 CF3 CF8M CF3M
17 Nut A194 2H A194 8 A194 8 A194 8M A194 8M
18 Bolt A193 B7 A193 B8 A193 B8 A193 B8M A193 B8M
19 Yoke WCB WCB Galvanization, CF8
Drive Actuator Handle, Electric actuator, Worm gear, Pheumatic actuaror


Metal Seated Butterfly Valve

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