Description

DOUBLE OFFSET RUBBER SEATED BUTTERFLY VALVE – TECHNICAL DATA SHEET

(Ductile Iron Body & Disc / Rubber Seat)

Project Name: ________________________
Item No.: ________________________
Tag No.: ________________________
Quantity: ________________________
Date: ________________________

1. VALVE GENERAL INFORMATION

Parameter	Specification
Valve Type	Double Offset Butterfly Valve (High Performance)
Body Construction	Wafer / Lug / Flanged (as required)
Body Material	Ductile Iron (ASTM A536 Grade 65-45-12 / GGG-50)
Disc Material	Ductile Iron (ASTM A536 Grade 65-45-12 / GGG-50) + Electroless Nickel Plating (ENP)
Seat Material	EPDM / NBR / Viton (Bonded or Replaceable Cartridge type)
Stem Material	Stainless Steel (AISI 416 / 431 / 304 / 316)
Bushings / Bearings	Self-lubricating PTFE / Bronze-backed PTFE
Nominal Size (DN / NPS)	2″ – 48″ (DN50 – DN1200)
Pressure Rating	Class 125 / Class 150 / PN10 / PN16 / PN25
End Connection	Wafer, Lug, or Flanged (RF / FF)
Design Standard	API 609 / ASME B16.34 / EN 593 / ISO 5752
Face-to-Face Standard	API 609, ISO 5752 Series 20 (Short) / Series 13 (Long)
Flange Drilling Standard	ASME B16.5 / ASME B16.47 / EN 1092 / JIS
Inspection & Test Standard	API 598 / ISO 5208 / EN 12266-1
Temperature Range	-30°C to +120°C (EPDM), -10°C to +80°C (NBR), -15°C to +150°C (Viton)

2. MATERIALS OF CONSTRUCTION

No.	Component	Material	Remarks
1	Body	Ductile Iron (ASTM A536 65-45-12 / EN-GJS-450-10)	Epoxy coated (internal/external, min. 300 μm)
2	Disc	Ductile Iron (ASTM A536) + Electroless Nickel Plating (ENP)	Corrosion resistant, smooth surface
3	Seat	EPDM Rubber (or NBR/Viton)	Bonded-in or replaceable cartridge design
4	Upper Stem	Stainless Steel (AISI 416 / 431)	Anti-blowout design
5	Lower Stem	Stainless Steel (AISI 416 / 431)	—
6	Bearings / Bushings	PTFE / Bronze	For low friction and wear resistance
7	Thrust Washer	PTFE / Stainless Steel	—
8	O-Rings / Seals	EPDM / Viton	For stem sealing
9	Nameplate	Stainless Steel / Aluminum	—
10	Fasteners	Stainless Steel (304)	For lug/flanged types

Alternative materials available upon request (e.g., Super Duplex, Alloy 20, etc.).

3. DESIGN FEATURES (DOUBLE OFFSET)

Feature	Description	Benefit
Double Offset Geometry	Two independent offsets: (1) stem axis offset from disc centerline; (2) disc centerline offset from pipe centerline	Cam-like sealing action minimizes rubbing, reduces torque and wear
Rubber Seat	Resilient elastomer seat (EPDM/NBR/Viton) provides bubble-tight shut-off	Zero leakage even at low pressure
Nickel Plated Disc	Electroless nickel plating gives excellent corrosion and erosion resistance	Prolongs service life in water/wastewater
Cartridge or Bonded Seat	Seat can be vulcanized to body or replaceable without removing actuator	Easy maintenance
Long Service Life	Double offset design eliminates “jamming” of disc against seat	Lower operating torque and longer seat life
Bi-directional Shut-off	Seals equally well in both flow directions	Flexible installation
Top Entry / Anti-blowout Stem	Stem retained with anti-blowout ring	Safety in case of internal pressure
Low Flow Resistance	Disc opens to 90° with minimal obstruction	Low pressure drop

4. APPLICABLE STANDARDS & SPECIFICATIONS

Item	Standard
Design & Manufacturing	API 609, ASME B16.34, EN 593
Face-to-Face Dimensions	API 609, ISO 5752 Series 20 / 13
Flange Connection	ASME B16.5, B16.47, EN 1092-2, JIS B2220
Inspection & Testing	API 598, ISO 5208, EN 12266-1
Coating	WRAS approved fusion-bonded epoxy, min. 300 μm

5. PRESSURE TEST (PER API 598)

Test Type	Description
Shell (Hydrostatic)	1.5 × rated pressure for Class 150 / PN16
High Pressure Seat Test	1.1 × rated pressure (water)
Low Pressure Seat Test	5–6 bar (air or nitrogen)
Leakage Rate	Zero (bubble-tight) per ISO 5208 Rate A

100% hydrostatic shell and seat tests, plus low pressure air test performed on every valve.

6. PERFORMANCE DATA

Parameter	Specification
Service Medium	Water, Wastewater, Oil, Gas, Mild Chemicals (depending on elastomer)
Design Temperature	See seat material selection
Max. Working Pressure	Up to 25 bar (PN25) / Class 150
Leakage Class	ISO 5208 Rate A / API 598 Class A (bubble-tight)
Operation Torque	Low due to double offset design
Installation Position	Any (horizontal, vertical, inclined)
Flow Direction	Bi-directional (marked on body)
Cracking Pressure	N/A (quarter-turn valve)

7. DIMENSIONS (Reference – Wafer Type, API 609 Short Pattern, Class 150)

DN (mm)	NPS (inch)	Face-to-Face L (mm)	Flange ØD (mm) – Drilling
50	2″	43	4 × 19 mm on 125 mm BC
80	3″	46	4 × 19 mm on 160 mm BC
100	4″	52	8 × 19 mm on 190 mm BC
150	6″	56	8 × 22 mm on 250 mm BC
200	8″	60	8 × 22 mm on 320 mm BC
250	10″	68	12 × 26 mm on 385 mm BC
300	12″	78	12 × 26 mm on 450 mm BC
350	14″	78	12 × 29 mm on 510 mm BC
400	16″	102	16 × 29 mm on 575 mm BC
450	18″	114	16 × 32 mm on 635 mm BC
500	20″	127	20 × 32 mm on 700 mm BC

For lugged or flanged types and other pressure ratings, please refer to API 609 or contact the manufacturer.

8. OPTIONAL UPGRADES

Option	Description
Seat Material	NBR, Viton, Silicone, PTFE (for higher temperatures)
Disc Material	CF8, CF8M, 2205, 2507, Aluminum Bronze, etc.
Body Material	Cast Iron, Carbon Steel WCB, Stainless Steel
Stem Material	AISI 304, 316, 17-4PH, Inconel
End Connection	Lugged or Flanged (RF, FF, RTJ)
Coating	Fusion-bonded epoxy (WRAS approved), NACE compliant
Operation	Lever, gearbox, electric/pneumatic actuator

9. QUALITY CONTROL

100% chemical analysis and mechanical testing on all heat numbers
100% DPT (dye penetrant) on castings; MT/UT/RT available as requested
100% hydrostatic shell and seat test, plus low pressure air seat test
All coatings thickness checked with calibrated gauges

10. WARRANTY

12 months service life at minimum; free spares and maintenance instruction provided when required.

This technical data sheet is for reference purposes only. All specifications are subject to change without prior notice. For specific project requirements, please consult the manufacturer.

Typical Rubber Seated Double Offset Butterfly Valve