Resilient Seated Butterfly Valve S31H Bray International

Resilient Seated Butterfly Valve

Series 31H

Size Range
NPS 2 to 20 / DN 50 to 500
Temperature Range
-20°F to 250°F (-29°C to 121°C)
Maximum Allowable Operating Pressure
250 psi (17.2 Bar)


Resilient Seated Butterfly Valve - Series 31H

Size Range
NPS 2 to 20 / DN 50 to 500
Body Materials
Cast Iron, Ductile Iron
Temperature Range
-20°F to 250°F (-29°C to 121°C)
Stem Materials
416 Stainless Steel
Maximum Allowable Operating Pressure
250 psi (17.2 Bar)
Seat Materials
Bonded EPDM, Bonded BUNA-N
Shutoff Rating
Bidirectional Bubble-tight
Disc Materials
Nylon 11 Coated Ductile Iron, Aluminum Bronze, Stainless Steel
Body Style
Testing Standard
MSS SP-61, API 598, EN 12266-1
ATEX, NSF 61/372, PED, PE(S)R, SIL
Face to Face
MSS SP-67, API 609 Category A, EN 558 Series 20
High Pressure, HVAC, Dead-End service

Features & Benefits

Series 31H lug-style resilient seated butterfly valve is drilled and tapped to meet ASME Class 125/150 and PN16 flanges. The durable, high strength one-piece stem design utilizes an efficient internal disc to stem connection.

Series 31H valves provide a primary and secondary seal between the disc and seat, as well as the stem and seat, ensuring the total encapsulation of line media with zero external leakage.

STEM RETAINING ASSEMBLY: The stem is retained in the body by means of a unique stainless steel Spirolox® retaining ring, a thrust washer and two C-rings, manufactured from brass as standard, stainless steel upon request.

STEM BUSHING: Non-corrosive, heavy duty acetal bushing absorbs actuator side thrust.

STEM SEAL: Double “U” cup seal design is self-adjusting and gives positive sealing in both directions.

PRIMARY AND SECONDARY SEALS: These seals prevent line media from coming in contact with the stem or body. The primary seal is an interference fit of the molded seat flat with the disc hub. The secondary seal is created because the stem diameter is greater than the diameter of the seat stem hole.

BODY: One piece wafer or lug style. Polyester coating for excellent corrosion resistance. Nylon 11 coating is available as an option.

SEAT: Bray’s tongue and groove seat design provides complete isolation of flowing media from the body. The seat also features a molded o-ring which eliminates the use of flange gaskets.

DISC: Casting is spherically machined and hand polished to provide a bubble tight shutoff, minimum torque, and longer seat life. Bray’s resilient Nylon 11 coating comes as standard.

STEM: Precision double “D” disc to stem connection drives the disc without the need for screws or pins. The close tolerance, double “D” connection that drives the valve disc is an exclusive feature of the Bray valve. Disassembly of the Bray stem is just a matter of pulling the stem out of the disc.

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