ANSI Stainless Steel Swing Flange Check Valves

ANSI Stainless Steel Swing Flange Check Valves are automatic shut-off valves designed and manufactured strictly to ANSI/ASME standards.They combine the corrosion resistance of stainless steel with the advantages of swing-type structure, mainly consisting of stainless steel body, bonnet, swing disc, hinge mechanism and flanged ends.

Working principle is simple and reliable:During forward flow, medium pressure rotates the disc around the hinge to open, ensuring smooth flow.In case of backflow, the disc closes automatically under its own weight and reverse pressure, tightly preventing backflow and protecting the piping system and downstream equipment.

Featuring firm and easy-to-maintain flanged connections and excellent corrosion resistance, these valves are widely used in ANSI piping systems for petrochemical, natural gas, food & pharmaceutical, water treatment and power plant industries.They are especially ideal for medium-low to medium-high pressure applications requiring automatic backflow prevention, high sealing and corrosion resistance.With compliance and practicality, ANSI Stainless Steel Swing Flange Check Valves have become key components ensuring unidirectional flow in ANSI piping systems.

Core Technical Parameters

Core Product Advantages

ANSI standard compliant, strong adaptability

Designed and manufactured strictly in accordance with ANSI/ASME, API and other American standards. It can be directly applied to various ANSI piping systems without extra modification, reducing procurement and installation costs.ANSI Stainless Steel Swing Flange Check Valves are key components for backflow prevention in ANSI pipelines.

All-stainless steel, corrosion-resistant and durable

Adopts ANSI stainless steel such as F304/CF8, F316/CF8M, with excellent corrosion, high temperature and wear resistance.It ensures stable long-term operation in sour, chlorinated and other corrosive media, reducing replacement frequency and maintenance cost.

Swing structure, high flow efficiency

Single/double/multi disc design suits different diameters. Smooth flow passage, low resistance and sensitive operation.Closing response as fast as 0.5s quickly blocks backflow, effectively protecting downstream pumps, compressors and equipment from water hammer.

Reliable sealing, wide application range

Hard seal for high temperature, particle-laden and high-wear conditions; soft seal for medium-low temperature and clean media.Firm flanged connection meets API 598 Class IV with zero visible leakage, suitable for low to medium-high pressure conditions.

No external drive, easy operation

Automatically opens and closes by medium pressure and disc gravity, no extra power required.Simple structure, stable performance, lower equipment investment and energy consumption.

Component Materials & Structure

(Highlight quality, ensure stable performance)

Core Component Materials

(ANSI compliant, quality controllable)

● Body / Bonnet: ASTM A182 F304/F316 (forged), ASTM A351 CF8/CF8M (cast), both meet ANSI material standards for different corrosive conditions.

● Disc: Same material as body + Stellite alloy overlay (ASTM A417 for hard seal), or stainless steel + PTFE soft seal ring (soft seal), balancing sealing and durability.

● Hinge mechanism: Forged 316 stainless steel; hinge shaft made of 174PH precipitation hardening stainless steel (ASTM A193 630), greatly improving wear resistance and strength to avoid jamming.

● Seals: Inconel alloy ring for high temperature; PTFE/perfluoroether rubber for medium-low temperature clean media; 316L spiral wound gasket (ANSI B16.20) for flange sealing.

● Bolts / Nuts: ASTM A193 B8/B8M (stainless steel bolts), ASTM A194 8/8M (matching nuts), comply with ANSI high-pressure fastening standards, matching body material for consistent corrosion resistance.

Structural Features

(Scientific design for ANSI conditions)

Swing-type structure with flexible single/double/multi disc options according to diameter. Flanged wafer/unitary structure for different installation needs.External hinge for easy maintenance.Straight-through flow design ensures low resistance and sensitive operation.With scientific structure, ANSI Stainless Steel Swing Flange Check Valves deliver practicality and stability for various ANSI pipeline applications.

Design & Manufacturing Standards

Selection Guidelines

Accurately match ANSI pressure class

Class150 (PN20) for low pressure; Class300 (PN50) for medium pressure; Class600 (PN100) for medium-high pressure.Strictly match pipeline Class to avoid overpressure. ANSI Stainless Steel Swing Flange Check Valves must be selected accordingly for safe operation.

Select disc structure by diameter

Small diameter (NPS 1/2"~2"): single disc swing type, low resistance, sensitive action.Large diameter (NPS 3" and above): double/multi disc, reduces vibration and water hammer risk.

Choose sealing type by working condition

High temperature (>200℃), particles or high wear → metal hard seal (Stellite overlay).Medium-low temperature (≤200℃), clean media → soft seal (PTFE/perfluoroether) for near-zero leakage.

Match material to medium corrosion

General non-corrosive media → 304 (F304/CF8).Chlorinated, sour or corrosive media → 316 (F316/CF8M).Severe corrosion → upgrade to special stainless steel for longer service life.

Match ANSI flange specification

Confirm facing type (RF/RJ) and material grade fully match pipeline flanges to prevent sealing failure.

Operation & Maintenance

(Extend service life, ensure stable operation)

Installation Notes

● Before installation: verify Class, material, diameter and flange facing match ANSI system. Check body, disc and hinge for damage. Manually test disc movement for smooth operation.

● Install according to flow direction arrow to ensure forward flow opens the disc. Reverse installation is strictly prohibited.

● Reserve sufficient clearance on the disc side for full opening, avoid obstruction by pipes or walls.

Routine Maintenance

● Regularly inspect flange and bonnet seals; retighten bolts or replace gaskets if leakage occurs.

● Periodically disassemble to clean internal debris, apply high-temperature grease on hinge shaft to prevent jamming.

● For high-flow or large-size applications, install water hammer arrestors downstream. Close upstream valves slowly to reduce shock.

Restart after Long-term Shutdown

Before restart: manually check disc movement, inspect interior for blockage or seal damage.Open medium slowly and gradually increase pressure and flow to avoid jamming or seal failure.

Application Fields

With ANSI compliance, corrosion resistance, reliable sealing and sensitive operation,ANSI Stainless Steel Swing Flange Check Valves are widely used in ANSI piping systems for:

● Petrochemical: corrosive media such as chemical fluid, sour oil, acid & alkali, low to medium-high pressure.

● Natural gas: natural gas and LPG pipelines, strong corrosion resistance, reliable backflow prevention.

● Food & pharmaceutical: clean medium pipelines, high-precision sealing, hygienic grade.

● Water treatment: chlorinated water, sewage and corrosive media treatment systems.

● Power industry: power station auxiliary systems and steam pipelines, high temperature and wear resistant.