Description

Technical Datasheet: Double Eccentric Rubber Seated Butterfly Valve

Project Name: ____________________ Item No.: ____________________
Tag No.: ____________________ Quantity: ____________________

1. General Information

Item	Standard Configuration	User Specification / Remarks
Valve Type	Double Eccentric (Double Offset) Butterfly Valve	Resilient seated, zero leakage
Design Standard	API 609 / BS5155 / ASME B16.34 / EN 593 / GB/T 12238	BS5155 is a common British Standard for butterfly valves
Face-to-Face	API 609 / ASME B16.10 / EN 558 Series 13/14/16 / BS5155
Flange Drilling	ASME B16.5 / ASME B16.47 / EN 1092-2 / GB/T 9115
Inspection & Test	API 598 / ISO 5208 / EN 12266-1
Pressure Rating	Class 150 / 300 / PN6 / PN10 / PN16 / PN25
Size Range	2″ – 48″ (DN50 – DN1200)	Larger sizes available upon request
Temperature Range	-29°C to +200°C (Depending on seat material)
End Connection	Wafer Type / Lug Type / Flanged Type
Operation	Lever / Gearbox / Pneumatic Actuator / Electric Actuator
Mounting Flange	ISO 5211 (For direct actuator mounting)

2. Design Features

Feature	Description	Benefit
Double Eccentric Design	Stem axis offset from both disc center and body centerline	Disc lifts off seat immediately upon opening, reducing friction and wear
“Cam Action” Operation	Disc rotates away from seat with minimal contact during opening/closing	Extends seat life, reduces operating torque
Bidirectional Sealing	Pressure assisted sealing in both flow directions	Flexible installation, no flow direction restriction
Blow-Out Proof Stem	Stem retained by internal shoulder and thrust bearing	Enhanced safety under pressure
Replaceable Seat	Seat can be replaced without disassembling disc or stem	Low maintenance cost
Self-Lubricating Bearings	PTFE/Bronze bearings for stem support	Smooth operation, corrosion resistance
Tapered Pin/Spline Connection	Secure disc-to-stem connection	No relative movement, long service life

3. Bill of Materials (Main Components)

No.	Part Name	Standard Material	Optional Material	Remarks
1	Body	Ductile Iron (ASTM A536 65-45-12 / GGG-50)	WCB / CF8 / CF8M / Cast Iron	Epoxy coated
2	Disc	Ductile Iron (ASTM A536 65-45-12 / GGG-50)	CF8 / CF8M / Aluminum Bronze / Nickel Plated DI	Disc edge polished
3	Seat	EPDM (Ethylene Propylene Diene Monomer)	Buna-N / Viton / PTFE / Silicone	Bonded or replaceable type
4	Seat Retainer / Ring	Stainless Steel / Carbon Steel	With O-ring protection
5	Stem / Shaft	Stainless Steel (AISI 410 / 304 / 316)	17-4PH / Monel K500	Blow-out proof
6	Bearings / Bushings	PTFE / Bronze / PTFE coated bronze	Self-lubricating
7	Thrust Washer	PTFE / Bronze
8	Packing / Stem Seal	O-Ring (EPDM / Viton) / PTFE V-Ring / Graphite	Multiple sealing system
9	End Cover / Bottom Plate	Ductile Iron / Stainless Steel
10	Taper Pins / Keys	Stainless Steel (A2 / 304)
11	Fasteners	Stainless Steel (A2 / 304)
12	Gearbox / Actuator	Cast Iron / Aluminum	IP67 / IP68 rated

4. Technical Parameters & Performance

Item	Specification
Medium	Water, Wastewater, Seawater, Cooling Water, Potable Water, Air, Mild Chemicals
Operating Temperature	EPDM: -30°C to +120°C / Buna-N: -20°C to +90°C / Viton: -20°C to +200°C
Max Operating Pressure	Up to 300 psi / 25 bar (De-rate at high temps)
Seat Type	Resilient Soft Seat – EPDM / Buna-N / Viton
Sealing Performance	Zero Leakage (Bubble tight) – API 598 / ISO 5208 Rate A
Leakage Class	ANSI/FCI 70-2 Class VI (Soft seated)
Flow Direction	Bidirectional
Flow Characteristic	Approximately linear / Modified equal percentage
Disc Type	Double eccentric design with streamlined profile
Seat Design	Pressure assisted – tighter seal with higher pressure
Cavity Free	No cavities for media entrapment
Suitable for	Dead-end service (Lug type) / Isolation service

5. Test Pressure (Reference: Class 150 / PN16)

Test Type	Pressure	Standard
Shell (Hydrostatic)	1.5 x Rated Pressure (425 psi / 2.9 MPa for Class 150)	API 598 / ISO 5208
Seat (Hydrostatic)	1.1 x Rated Pressure (315 psi / 2.2 MPa for Class 150)	API 598 / ISO 5208
Low Pressure Seat (Air)	80 psi / 0.6 MPa	Bubble tight (Zero leakage)

6. Dimensions & Weight (Reference: Wafer Type, API 609 / EN 558 Series 13)

NPS	DN (mm)	L (Face-to-Face) mm	H (Overall) mm (approx)	Weight (kg) approx
2″	50	43	120	4
3″	80	64	140	6
4″	100	64	160	8
6″	150	76	200	14
8″	200	89	240	22
10″	250	114	280	32
12″	300	114	320	45
14″	350	127	360	60
16″	400	140	400	80
18″	450	152	440	105
20″	500	152	480	130
24″	600	178	550	185
(Note: For Lug type, weight is slightly higher. For higher pressure classes or exact dimensions, refer to certified GA drawing. Add actuator weight separately.)

7. Special Requirements / Options

Seat Material: EPDM (Standard) / Buna-N (NBR) / Viton (FKM) / PTFE / Silicone / Hypalon
Seat Design: Bonded seat (Integral) / Replaceable cartridge seat (Field replaceable)
Disc Material: Ductile Iron (Standard) / Stainless Steel 304/316 / Aluminum Bronze / Nickel Plated DI / Nylon Coated
Stem Material: Stainless Steel 410 (Standard) / 304 / 316 / 17-4PH / Monel K500 / Duplex
Body Material: Ductile Iron (Standard) / WCB / CF8/CF8M / Cast Iron
Body Coating: Epoxy coating (Min. 250 microns) – Color: Blue RAL 5017 / RAL 5015 / Custom
Connection Type: Wafer (Standard) / Lug (For dead-end service) / Flanged (Double flanged)
Operation: Lever (Small sizes) / Gearbox (Standard) / Pneumatic Actuator / Electric Actuator / Hydraulic Actuator
Gearbox Type: IP67 / IP68 sealed / with locking device / with position indicator
Stem Extension: Yes / No (For buried service)
Test Certificate: EN 10204 Type 2.2 / 3.1
Special Cleaning: For Potable Water (NSF/ANSI 61 / WRAS / DVGW) / For Oxygen service
NACE Compliance: MR0175 / ISO 15156 (For modified materials)
Fire Safe Design: API 607 / ISO 10497 compliant (Optional)

Design Notes:

Double Eccentric Design: The double offset (stem behind disc center and body centerline) creates a cam action during operation. When the valve opens, the disc lifts off the seat immediately, eliminating friction and wear during the first 10-15 degrees of travel. When closing, the disc only contacts the seat in the final degrees of travel, providing tight shut-off with minimal torque.
Pressure Assisted Sealing: The resilient seat is designed to deform under line pressure, creating tighter seal as pressure increases. This ensures bubble-tight shut-off even at high pressures.
ISO 5211 Mounting: Top flange conforms to ISO 5211 standard, allowing direct mounting of actuators without brackets, reducing stack height and improving alignment.
Dry Shaft Design: Stem is isolated from the medium by multiple O-rings, preventing corrosion and ensuring long-term operability.

Material Notes:

EPDM Seat: Excellent resistance to hot water, steam, ozone, UV, and mild chemicals. Ideal for water, wastewater, and potable water service. Not recommended for oils, hydrocarbons, or solvents.
Ductile Iron Body/Disc: High strength, excellent impact resistance, commonly used in water and wastewater applications.
Stainless Steel Stem: Ensures corrosion resistance and long service life.

Application Notes:

Suitable for: Water distribution, wastewater treatment, pumping stations, HVAC, cooling water systems, fire protection, irrigation, and industrial process water.
Not suitable for: Dry abrasive media, high-temperature steam (>120°C for EPDM), hydrocarbons (use Viton instead).
Installation: Can be installed in any position. For vertical installation with actuator, ensure proper support.

Note: This datasheet is prepared for a Double Eccentric Rubber Seated Butterfly Valve with resilient seat design. Ensure selected seat material is compatible with the specific service medium and temperature range. For modulating control applications, consult factory for sizing and selection.

BS5155 Rubber Seated Double Offset Butterfly Valve