Dual plate Check valve - BB | Gestra

GESTRA BB DISCOCHECK – Dual Plate Check Valve

The GESTRA BB is a wafer-type dual plate check valve designed for installation between flanges. It features two independently moving plates, dual shafts, and four springs. The valve operates without an actuator; closure is achieved via spring force and differential pressure. Suitable for both horizontal and vertical pipe runs to prevent reverse flow.

Variants and Connections

• BB 3…C: Carbon steel body (1.0619 / SA216 WCB)
• BB 3…A: Stainless steel body (1.4408 / SA351 CF8M)
• EN Series: DN50–DN500, PN10/16/25/40, EN 1092-1 flanges
• ASME Series: NPS 2"–20", Class 150/300, ASME B16.5 RF flanges
• Face-to-face: EN 558 Series 16 or API 594, depending on version

Sealing and Spring Options

Standard seat is metal-to-metal. Soft seat options include EPDM, FPM/FKM, NBR, PTFE, selected based on temperature and chemical compatibility. EPDM, NBR, and FPM seats meet EN 12266-1 leakage rate A; metal-to-metal and PTFE correspond to leakage rate G.

Spring selection depends on installation orientation: 7 WA for horizontal flow, 2 WA for reduced opening pressure, 5 VO for vertical downward flow, and Inconel springs for temperatures above 300°C.

Applications

Applicable for water, steam, condensate, gases, and industrial liquids. Suitable for fluid groups 1 and 2 per PED (A/C versions). Commonly used in steam systems, pump discharge lines, chemical plants, utilities, cooling water, and process piping.

Installation Guidelines

Install in clean piping with correct flow direction and flange alignment. Manufacturer recommends at least 5×DN upstream for flow stabilization. For pulsating flow (e.g., near compressors), special assessment or versions may be required.

FAQ

When is a damper required? In lines subject to water hammer or rapid flow changes.
When is DN-based selection insufficient? When flow drops below the valve’s minimum stable region, leading to increased noise and wear.