Bellows Sealed Gate Valves

About DIN and ANSI Bellows Sealed Gate Valves

A bellows sealed gate valve is an isolation valve in which a welded metal bellows sits around the stem, forming a metal barrier between the process fluid and the atmosphere. Conventional gate valves rely on gland packing alone to seal the stem, and packing can weep as it wears or as the stem moves. With a bellows seal the stem can still travel up and down to raise and lower the gate, while the fluid is contained by the bellows itself.

Two models are listed here. On the DIN Standard Bellows Sealed Gate Valve, the lower end of the metal bellows is automatically welded to the stem assembly and the upper end to a connecting plate, creating a complete metal seal designed to prevent stem leakage. The ANSI Standard Bellows Sealed Gate Valve uses the same welded bellows construction and adds a double seal design, with gland packing behind the bellows as a second line of protection.

Choosing between them mainly comes down to the piping standard used on your plant: DIN for metric, PN-rated systems and ANSI for ASME-class pipework. Bellows sealed valves are generally specified for media where stem emissions must be avoided, such as thermal oil, toxic or hazardous chemicals, vacuum lines and high-value fluids.

• Gate valves are for full-open or full-closed isolation, not throttling
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