Check Valves for Power Generation

Yes. Vajra Industrial Solutions supplies IBR-certified check valves for boiler and steam service across the full size range from DN15 to DN600, in Class 150 through Class 2500. IBR certification involves material approval (the specific heat/charge of the casting or forging must be IBR approved), design calculations submitted to the state or central boiler inspector, hydrostatic pressure testing at 1.5× design pressure witnessed by an IBR inspector, and a stamp on the valve and an IBR certificate in the documentation package. For orders requiring IBR certification, provide the project state (Maharashtra, Gujarat, etc.) with your purchase order as each state's inspector has specific requirements. Standard lead time for IBR-certified valves is 8–14 weeks for alloy steel (WC6, WC9) and 12–18 weeks for P91.

Water hammer at the BFP check valve occurs when: the running pump trips suddenly; flow reverses in the BFP discharge line; a slow-closing swing check valve is still open when full reverse flow velocity (typically 2–4 m/s in BFP lines) has developed; the disc slams shut abruptly against the seat, generating a pressure transient (Joukowsky pressure rise = ρ × c × ΔV, which can reach 50–100 bar in high-velocity BFP systems). Prevention: (1) Tilting disc check valve with inherent closing torque — closes before full reverse velocity; (2) Non-return valve with dashpot (hydraulic damper on the disc arm) — controlled slow final closing eliminates slam; (3) Anti-slam check valve with spring-loaded disc — cracking open with forward flow, closing under spring force when differential drops, before reverse flow; (4) Variable speed drives on BFPs — controlled ramp-down reduces reverse flow rate. Vajra recommends tilting disc non-return valves for all BFP discharge service.

Standard swing check valves are not suitable for vertical upward flow installations because the disc hangs under gravity rather than being held open by flow; at low-flow conditions the disc will flutter partially closed, causing chattering damage to disc and seat. Solutions for vertical upward flow: (1) Tilting disc check valve — the disc geometry creates self-closing torque but the disc opens against gravity under forward flow; suitable for vertical-up installation; (2) Spring-loaded dual plate check valve — the spring holds the disc partially open, ensuring it stays open under low forward flow, and provides closing force in reverse flow; suitable for vertical and horizontal installation; (3) Piston (lift) check valve — spring-loaded piston works in any orientation including vertical upward; suitable for small bore (DN15–DN100) high-pressure service. For large-bore (DN150+) vertical upward installation in power plant service: specify tilting disc or spring-loaded dual plate check valve and confirm vertical installation on the purchase order.