ANSI 150 Double Flanged Butterfly Valve — Ductile Iron Body, SS304 Disc, EPDM Seat, API 609

The double flanged butterfly valve is the most robust design with the longest face-to-face dimension in the iron butterfly family — its integrally cast flanges on the body make it radically different from the wafer butterfly (flangeless, between pipe flanges) and the Lug butterfly (threaded bolt holes). By having its own flanges, the valve bolts directly to the pipe flanges with independent bolts on each side — just like any other flanged component (gate, globe, check valves) — without relying on through-bolts that pass through both flanges. This construction makes it the standard option for large diameters where the butterfly's face-to-face length is sufficient so that the pipe flanges do not need to be perfectly aligned, and where the valve's weight in large diameters requires the structural rigidity of integral flanges. Body in ductile iron, disc in SS304 (CF8), stem in SS420, and replaceable EPDM seat in accordance with API 609.

Double Flanged vs. Wafer vs. Lug — the three types of butterfly valves and when to use each

Integral flanges — why they matter in large diameters

In small diameters (2" to 6"), wafer and Lug butterfly valves are perfectly viable — through-bolts are short, pipe flanges are perfectly aligned, and valve weight is manageable. In large diameters (8" and above), problems arise that the double flanged design solves:

• Structural rigidity: A 16" or 20" wafer butterfly has considerable weight — pipe flanges must support this weight laterally. The integral flanges of the double flanged valve better distribute the mechanical loads from the valve's weight and pipe forces over the body.
• Tolerance to misalignment: In large diameters, perfect alignment of two pipe flanges separated by the valve's face-to-face length is harder to achieve in the field. The integral flanges of the double flanged valve are machined with greater precision than the assembly of two pipe flanges — reducing the risk of leaks at joints due to misalignment.
• Easier installation: The double flanged valve installs and removes exactly like a gate or globe valve — without the through-bolt coordination required for a wafer butterfly in large diameters.

Construction Materials

Technical Specifications

• Type: Double flanged butterfly valve
• Design Standard: API 609
• Actuator Mounting: ISO 5211
• Flange Drilling: ANSI 150
• Body Material: Ductile iron
• Disc: SS304 (CF8)
• Stem: SS420
• Seat: EPDM — field replaceable
• Nominal Pressure: PN16 (230 psi / 16 bar) at ambient temperature
• Working Temperature: -20 °C to +110 °C

Fluid Compatibility

• ✅ Potable water and municipal water in large diameters
• ✅ Clean industrial process water
• ✅ HVAC water — chilled water and hot water up to 110 °C
• ✅ Chlorinated water up to 5 ppm
• ✅ Non-corrosive wastewater with fine solids
• ✅ Compressed air and non-corrosive gases
• ⚠️ Water with high chlorides: SS304 disc may suffer pitting — consult version with SS316 disc
• ⚠️ Temperature above 110 °C: EPDM deteriorates — consult version with Viton seat
• ❌ Hydrocarbons: EPDM not compatible
• ❌ Aggressive acids and alkalis: ductile iron body does not resist

Automation — ISO 5211 in large diameters

The ISO 5211 mounting allows the double flanged butterfly valve to be automated with pneumatic or electric actuators. In large diameters (8" and above), the operating torque is significant — Cematic sizes the correct actuator with the verified safety factor for each diameter and process pressure:

• Single or double-acting pneumatic actuator: First choice for large diameters where response speed and torque are priorities. Single-acting NC ensures closure upon air supply failure. View butterfly valves with pneumatic actuator →
• Gearbox with handwheel: For large diameters where frequent manual operation is required and the necessary torque exceeds the capacity of a lever — the gearbox multiplies the operator's force for tight closure.
• ON/OFF or modulating electric actuator: For installations without a compressed air network or with SCADA integration. View butterfly valves with electric actuator →

Main Applications

• Municipal potable water distribution — large diameters: The most frequent application of the double flanged butterfly valve in Mexico. Municipal potable water distribution networks in diameters from 8" to 24" use double flanged butterfly valves as section isolation valves. Water operating agencies (SACMEX, CONAGUA, SIAPA, regional OOA) specify the double flanged valve for these diameters in accordance with potable water network design standards.
• Water treatment plants (WTP and WWTP) — large diameters: Isolation of sections in raw water, treated water, and effluent lines in treatment plants where main line diameters exceed 8". The double flanged valve provides the necessary structural rigidity for larger diameter valves in these installations.
• High-flow pumping systems: Isolation valves on the suction and discharge of high-flow pumps in municipal, industrial, and irrigation pumping stations. Ductile iron resists mechanical vibrations from pumps, and EPDM covers standard pumping water.
• Industrial HVAC — large buildings and facilities: Distribution of chilled water and hot water in climate control systems for large-scale facilities — airports, hospitals, shopping centers, and industrial campuses — where main piping diameters require the double flanged butterfly valve.
• Large-scale agricultural irrigation systems: Irrigation canals, distribution systems for irrigation districts, and pressurized irrigation headers in large-scale agriculture where main distribution diameters are 8" to 20" or more.
• General industry — large diameter process lines: Any industrial application with large diameter process lines with fluids compatible with ductile iron and EPDM — cooling water, process water, industrial effluents — where the double flanged valve provides the necessary robustness and ease of installation.

For the flangeless, more compact wafer version, see iron wafer butterfly valve →
For the Lug version with dead-end service in smaller diameters, see Lug ANSI 150 butterfly valve →

Technical Data Sheet (Spanish)

Data Sheet (English)