Flap Type NRV | Flanged Swing Check Valve NRV Supplier India | CI DI WCB SS304 SS316 | IS 5312 | DN50–DN1000 | PN10 PN16 | Pump Station Municipal Water | KELOR

Description

Flanged Swing Check Valve (Flap Type NRV) Supplier India | CI / DI / WCB / SS304 / SS316 | IS 5312 | DN50–DN1000 | PN10–PN16 | Municipal Water / Pump Station / Sewage / Industrial | KELOR

Supplier: Krishna Industries (KELOR) – Ahmedabad, Gujarat, India
Established: 2017 | GSTIN: 24AKLPP6499B1ZT | IEC: AKLPP6499B
MOQ: 10 Nos | Body: CI / DI / WCB / SS304 / SS316
Standard: IS 5312 / API 598 | Sizes: DN50–DN1000 | Pressure: PN10 / PN16

Flanged Swing Check Valve Supplier in India

Krishna Industries (KELOR), based in Ahmedabad, Gujarat, is a B2B supplier of Flanged Swing Check Valves (Flap Type NRV) — Cast Iron (CI IS 210 / IS 5312) / Ductile Iron (DI ASTM A536) / WCB (ASTM A216) / SS304 (CF8 ASTM A351) / SS316 (CF8M ASTM A351) body — single flap full bore hinged disc — CI / DI / SS304 / Bronze disc — metal-to-metal or soft seat — integral flanges PN10 / PN16 (IS 5312) / Class 150 / Class 300 (ASME B16.5) — DN50 (2″) to DN1000 (40″) — horizontal and vertical installation — counterweight / spring assist / dashpot water hammer prevention options — IS 5312 / API 598 tested — GST invoice — MOQ 10 Nos — Pan India dispatch from Ahmedabad.

The flanged swing check valve is the standard pump discharge non-return valve for Indian municipal water supply, sewage rising mains, fire pump stations, and large bore industrial pumping systems — specified wherever IS 5312 is the project standard, where DN300 and above requires a self-supporting flanged body, and where counterweight or dashpot slam prevention is required to protect long pipeline systems from water hammer.

Flanged Body vs Wafer Type Swing Check Valve — Which to Specify

Water Hammer and Slam Prevention

The primary failure mode of swing check valves in pump discharge service is disc slam — and in large bore municipal pump stations, the resulting water hammer is the leading cause of pipeline joint failure, valve damage, and pump seal failure. Understanding the mechanism and the available prevention options is essential before specifying a swing check valve for any pump discharge application.

Why Disc Slam Occurs

When a pump trips, forward flow in the discharge pipeline decelerates rapidly. The water column in the rising main continues moving forward briefly under its own momentum, then decelerates and begins to reverse. The check valve disc, which was held open by forward flow, begins to swing shut under gravity as flow decelerates. If the disc is still partially open when reverse flow starts, the reverse flow accelerates the disc rapidly toward the seat — the disc slams against the seat at high velocity, generating a sharp pressure wave (water hammer) that propagates through the entire pipeline. In long rising mains DN300 and above, this pressure wave can reach several bar above normal operating pressure and cause pipe joint failure, valve body cracking, and pump mechanical seal damage.

Body and Disc Material Selection

Technical Specifications

Applications in Indian Industries

• Municipal water supply pump stations — GWSSB, MCGM, Chennai Metrowater, HMWSSB — CI IS 5312 PN16 with SS304 disc — DN150–DN600 — pump discharge NRV on main and standby pumps — counterweight standard on DN300+ — IS 5312 Part 1 compliance mandatory for government tender supply — flanged CI swing NRV is the dominant NRV type specified in Indian municipal water supply pump station tenders — test certificate to IS 5312 supplied with each valve
• Sewage rising mains and STP pump stations — CI or DI IS 5312 PN10/PN16 DN150–DN1000 — sewage pump discharge NRV — DI body for large bore DN400+ where CI body weight becomes a structural issue — dashpot or counterweight for long rising mains where water hammer risk is high — rubber soft seat for tight shut-off on sewage (prevents backflow odour through leaking seat) — flanged body for independent removal during pump maintenance
• Fire pump stations — IS 15301 / NFPA 20 — CI or WCB flanged swing NRV DN80–DN300 — jockey pump, main electric pump, and diesel backup pump discharge NRVs — IS 5312 CI body standard for Indian fire pump station specifications — fast-closing design important (fire pump trips must not allow backflow through main pump when jockey pump maintains pressure)
• Industrial large bore pumping — mining dewatering, power plant cooling water — DI or WCB DN200–DN600 — mine dewatering sump pump discharge — power plant cooling water pump discharge — high flow velocity at large bore — dashpot specified for long underground mine dewatering rising mains where water hammer can damage shafts and pipes — DI body for higher mechanical strength in mining environment
• Chemical and process plant pump discharge — SS316 CF8M Class 150/300 DN50–DN300 — corrosive chemical pump discharge NRV — acid transfer pump outlet, alkali dosing pump discharge, seawater intake pump station — SS316 body and disc for full corrosion resistance — Class 150/300 flanged per ASME B16.5 for process plant piping class compliance

Related Products — Krishna Industries (KELOR)

• Wafer Swing Check Valve — wafer body (no integral flanges) — compact face-to-face — DN50–DN300 — process plant, HVAC, chemical pump discharge where IS 5312 is not specified and compact installation is required
• Single Plate Wafer Check Valve (NRV) — single plate spring-loaded wafer NRV — very low cracking pressure — compact — DN50–DN300 — process plant pump discharge where spring-loaded closing is preferred
• Dual Plate Check Valve — dual plate spring-loaded wafer NRV — short face-to-face — fast closing — lower water hammer than single plate swing — DN50–DN600 — alternative to flanged swing NRV where compact face-to-face is critical
• Cast Iron Gate Valve — install on pump suction and discharge headers in pump stations — isolation gate valve on same IS 5312 / IS 14846 specification alongside flanged swing NRV on discharge
• Y Strainer — install upstream of pump (on suction) in pump stations — removes debris that causes disc and seat wear in swing NRV on discharge

Frequently Asked Questions

1. What is the difference between a flap type NRV and a dual plate check valve for pump discharge service?

A flanged swing check valve (flap type NRV) has a single full-bore hinged disc that swings open on forward flow and closes under gravity and reverse pressure. It is the IS 5312 standard design for Indian municipal pump stations — proven, simple, and maintainable through the removable top cover. A dual plate check valve has two spring-loaded half-discs in a wafer body — the spring loading means the discs begin closing before flow reversal, which significantly reduces water hammer. The dual plate wafer valve has a much shorter face-to-face dimension and is more compact. For most Indian municipal pump station projects where IS 5312 is specified, the flanged swing NRV is the compliant product. Where the project specification allows API 594 or EN 16767 dual plate check valves, the dual plate is a good alternative at DN300 and below where water hammer is the primary concern. At DN600 and above, the flanged swing NRV with dashpot remains the standard Indian specification.

2. Can a flanged swing check valve be installed vertically?

Yes — with the correct specification. A standard flanged swing NRV is designed for horizontal pipeline installation where gravity assists disc closure. For vertical pipeline installation with upward flow, the disc must be spring-loaded or counterweighted to close against the upward flow direction — gravity alone is insufficient and the disc may remain partially open when flow stops, allowing reverse flow. When ordering for vertical installation, specify this explicitly so the correct disc loading is supplied. Most Indian pump station vertical discharge risers above ground use flanged swing NRV with counterweight for vertical service.

3. When should I specify IS 5312 vs ASME B16.34 for a flanged swing check valve?

IS 5312 is the Indian standard specifically for swing check valves for water works purposes — it defines face-to-face dimensions, body materials (CI and DI), pressure ratings (PN10/PN16), and testing requirements for municipal water supply and sewage applications. Specify IS 5312 for all Indian municipal water supply, sewage, and pump station projects — government tenders will specify IS 5312 explicitly and non-compliant valves will be rejected. ASME B16.34 applies to industrial process plant valves in carbon steel (WCB) and stainless steel body materials for process piping — Class 150/300 flanged. Specify ASME B16.34 for industrial process pump discharge NRVs in chemical, pharma, oil and gas, and power plant service where CI/DI IS 5312 body is not specified and higher pressure classes or corrosion-resistant materials are required.

4. What documents are supplied with flanged swing check valve orders?

Standard supply includes GST invoice with HSN code and packing list. On request: IS 5312 test certificate (shell test and seat leakage test results) — required for most municipal tender supplies. MTC (Material Test Certificate) for body material (CI IS 210 heat analysis, or SS A351 chemical and mechanical properties) — for process plant and critical service orders. Dimensional inspection report confirming face-to-face and flange drilling per IS 5312 / ASME B16.5 — for EPC project quality records. Third party inspection (TPI) release note (Lloyds, BV, TÜV) for orders specifying TPI as per project quality plan.

5. What is the MOQ?

MOQ is 10 Nos. Municipal pump station and infrastructure project orders — typically 10 to 200+ Nos across sizes — with IS 5312 test certificate, MTC on request, dimensional report, and GST invoice. Specify body material, disc material, size, pressure rating (PN10/PN16 or Class 150/300), seat type (metal or soft), installation orientation (horizontal/vertical), and water hammer prevention requirement (standard / counterweight / spring / dashpot) when requesting pricing. WhatsApp complete specification and size list for project pricing within 2 hours.

Conclusion

Krishna Industries (KELOR) supplies Flanged Swing Check Valves (Flap Type NRV) for municipal water supply, sewage rising mains, pump stations, fire pump stations, and industrial large bore pumping — Cast Iron (CI IS 210 / IS 5312) / Ductile Iron (DI) / WCB (ASTM A216) / SS304 (CF8) / SS316 (CF8M) body — single flap full bore hinged disc — CI / DI / SS304 / Bronze disc — metal-to-metal or soft seat — PN10 / PN16 (IS 5312) / Class 150 / Class 300 (ASME B16.5) — DN50 (2″) to DN1000 (40″) — counterweight / spring assist / hydraulic dashpot water hammer prevention options — IS 5312 / API 598 tested — GST invoice — Pan India dispatch from Ahmedabad. WhatsApp body material, disc material, size, pressure rating, and water hammer prevention requirement for project pricing within 2 hours.