Flanged Flexible Seal Butterfly Valve

 

Flanged butterfly valve with flexible rubber seat for bubble-tight shut-off. Designed for water, wastewater, and industrial pipelines where flanged connections are required.

 

 

Item	Specification
Valve Type	Flanged Flexible Seal Butterfly Valve
Connection Type	Flanged (EN 1092-2 / ANSI B16.1 / BS 10 / JIS)
Nominal Size	DN50 – DN1200
Pressure Rating	PN10 / PN16 / ANSI150 (Custom PN25 available)
Seat Type	Flexible rubber (fully vulcanized or replaceable)
Body Material	ASTM A536 / EN GJS-450 Ductile Iron
Disc Material	SS304 / SS316 / Coated Ductile Iron
Seat Material	EPDM (Standard) / NBR / FKM / PTFE
Stem Material	SS304 / SS316
Top Flange	ISO 5211 for actuator mounting
Coating	Fusion Bonded Epoxy (250-300 microns)
Standards	EN 593 / API 609 / ISO 5752

 

 

Flanged Ends Bolt Directly to Your Pipeline
No alignment worries. No gasket slipping. Bolt the valve directly to your pipe flanges. The flanged design gives you a secure, leak-free connection every time.

Flexible Rubber Seat Provides Bubble-Tight Shut-Off
The flexible seat presses tightly against the disc edge. When you close the valve, the rubber wraps around the disc. No water passes through. Zero leakage. ISO 5208 Rate A certified.

Full Flange Drilling to Your Local Standard
EN 1092-2 for Europe. ANSI B16.1 for USA. BS 10 for UK. JIS for Japan. We drill to your standard. No field modification needed. Bolt holes align perfectly.

Ductile Iron Body Gives You Strength
Grey iron cracks. Ductile iron bends. Our valve body uses EN-GJS-450 ductile iron. 450 MPa tensile strength. 12% elongation. Handles pressure surges and pipe stress.

Flexible Seat Design Has Two Configuration Options
Fully vulcanized seat bonds to the body. No leak path behind the seat. Replaceable seat allows field service without removing the valve from the line. Tell us your preference.

 

 

Low Flow Resistance Saves Pumping Energy
The streamlined disc creates very little pressure drop. When fully open, the disc sits edge-on to the flow. Water passes freely. Your pump works less. Energy bills go down.

Corrosion-Resistant Epoxy Coating Included
We coat every valve body with fusion bonded epoxy. 250-300 microns thick. RAL 5005 blue standard. Protects against rust, chemicals, and weather. Buried or above ground both fine.

Stainless Steel Disc and Stem Options
SS304 standard for fresh water. SS316 for salt water and aggressive chemicals. No rust. No pitting. Long service life even in tough conditions.

Manual or Actuated – Same Valve
Order with hand lever for manual operation. Add electric or pneumatic actuator later. The ISO 5211 top flange accepts all standard actuators. No need to buy a new valve.

Replaceable Seat Extends Valve Life (Option)
The seat wears out after many cycles. With replaceable seat design, you change just the seat. Keep the valve body. Keep the disc. Keep the stem. Lower lifetime cost.

 

 

Water Pump Stations – Flanged connections at pump suction and discharge. Easy to remove when pump needs service.

Water Treatment Plants – Complex piping inside buildings. Flanged valves bolt to pipes, strainers, and equipment.

Sewage Treatment Plants – Flanged valves at aeration basins and clarifiers. EPDM seat resists sewage chemicals.

Valve Vaults and Manholes – Flanged connections allow valve removal without cutting pipe. Maintenance crews appreciate this.

Industrial Cooling Water – Flanged valves at heat exchangers and cooling towers. Regular maintenance requires disassembly.

Fire Pump Rooms – Flanged fire protection valves. High pressure rating for fire system demands. Bolted connections are secure.

HVAC Mechanical Rooms – Flanged chilled water and hot water valves. Easy to service. Easy to replace.

Chemical Dosing Stations – Flanged connections for chemical injection lines. FKM seat resists aggressive chemicals.

Food and Beverage Processing – Flanged sanitary valves. PTFE seat for food contact. Stainless steel disc and stem.

 

 

Seat Material	Temperature Range	Best For	Color Code
EPDM	-20°C to 80°C	Water, wastewater, mild chemicals	Red or black
NBR	-10°C to 80°C	Oils, fuels, hydraulic fluids	Yellow or blue
FKM (Viton)	-10°C to 150°C	High temperature, aggressive chemicals	Green or brown
PTFE (encapsulated)	-20°C to 150°C	Strong acids, food, pharmaceutical	White or grey

 

 

Hand Lever with Locking Plate – Standard on manual valves (DN50-DN300). Locks at 10 positions between 0° and 90°. Insert padlock to prevent unauthorized operation.

Worm Gear Operator – For DN350 and larger. Also recommended for DN250-DN300 with high pressure. Self-locking. Position indicator included. Handwheel for operation.

Limit Switch Box – Mounts on ISO 5211 top flange. Provides open/closed electrical feedback to control room. Mechanical or proximity switches. Weatherproof enclosure.

Pneumatic Actuator – Double-acting or spring-return (failsafe). For automated operation using plant compressed air. Includes solenoid valve and speed controllers.

Electric Actuator – On-off or modulating (4-20mA) control. Weatherproof (IP67) or explosion-proof (ATEX). Manual override handwheel standard.

Positioner (Modulating Control) – Converts 4-20mA or 0-10V signal to precise disc position. Accuracy within +/- 1%. For pneumatic or electric actuators.

Full-Face EPDM Gaskets – For flanged connections. 3mm thick. Matches valve flange dimensions. One gasket per flange connection.

Stainless Steel Disc and Stem Upgrade – SS316 for salt water, chlorides, and aggressive chemicals. No pitting. No crevice corrosion.

 

 

Air-Tightness Test (ISO 5208 Rate A):

Close valve. Apply 0.6 bar air pressure to one side.

Submerge valve in water tank (or apply soap solution to seat area).

Watch for bubbles for 60 seconds.

Requirement: Zero bubbles. No visible leakage.

Result: Pass / Fail recorded on each valve.

Hydrostatic Seat Test (High Pressure):

Close valve. Fill with water.

Apply 1.1 times rated pressure (PN16 → 17.6 bar).

Hold pressure for 60 seconds.

Measure any water passing through seat.

Requirement: Zero leakage for soft-seated valves.

Result recorded on test certificate.

 

 

Before Installation:

Inspect valve for shipping damage. Check flange faces for scratches.

Verify flange drilling matches your pipe flanges.

Check gasket size and material.

Installation Steps:

Place gasket between pipe flange and valve flange.

Align bolt holes. Use alignment pins for large flanges.

Insert bolts. Lubricate threads if needed.

Tighten bolts by hand in cross (star) pattern.

First torque pass: 30-40% of final torque.

Second torque pass: 70-80% of final torque.

Final torque pass: 100% of final torque (use torque wrench).

Repeat cross pattern for all passes.