Flanged

Marine double flanged butterfly valves are used in shipboard piping systems where short face-to-face length, rigid mechanical connection, and quarter-turn shut-off or limited throttling are required. The double flanged body allows direct installation between mating pipeline flanges and differs from wafer and lug designs in face-to-face dimensions, body support, and response to piping loads.

This category includes the Alfa Europe S36 butterfly valve, JIS Short Double Flanged type, with bonded liner and flange drilling to JIS B 2211 5K/10K. The stated size range is DN50 to DN1000, with face-to-face dimensions to JIS F-7480 and operating temperature range from -23 to +120 °C.

Available body materials include EN-JS 1030 ductile iron, stainless steel 1.4408, ASTM A216 WCB, and aluminium bronze BS 1400 AB2. For seawater, ballast, and cooling water service, body and disc material selection should be based on corrosion resistance, water conductivity, suspended solids content, and ship class requirements. The NBR seat should be assessed for temperature limit, chemical compatibility, oil contamination, and expected cycling frequency.

During selection and installation, the JIS flange rating, piping alignment, disc clearance, operating torque, access to lever or actuator, and liner replacement provisions should be verified. In throttling duty, differential pressure and disc opening angle affect noise generation, vibration, seat wear, and shut-off tightness. These valves are generally selected for isolation service; where flow regulation is required, the operating envelope should be reviewed against cavitation risk, erosion tendency, and permissible leakage class.