4A Swing Check Valve (ANSI)
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Performance, Precautions, and Differences from A182 F51 of Freeman Valve's ASTM A995 Gr. 4A ANSI check valve

 

ASTM A995 Gr. 4A (formerly CD3MN), as a cast version of 2205 duplex stainless steel, is an ideal ANSI check valve material for chloride-containing environments due to its excellent resistance to chloride ion corrosion. The following focuses on the core advantages, usage precautions, differences from the forged version (ASTM A182 F51), and its shortcomings of this ANSI check valve model manufactured by Freeman Valve.

 

1. Core Advantages of Freeman Valve's ASTM A995 Gr. 4A ANSI check valve in Resisting Chloride Ion Corrosion

 

1.1 Excellent Resistance to Chloride Ion Stress Corrosion Cracking (SCC)

 

This is the most crucial advantage of this ANSI check valve model and the key reason why it replaces the traditional CF3M ANSI check valve. From a mechanistic perspective, ASTM A995 Gr. 4A employs a ferrite (F) + austenite (A) dual-phase microstructure, completely breaking the SCC sensitivity mechanism of pure austenitic stainless steel under the coupled effects of chloride ions and tensile stress. The ferrite phase effectively inhibits crack propagation, significantly improving the ANSI check valve's SCC threshold.

 

In practical applications, this ANSI check valve exhibits far superior corrosion resistance to 304 and 316L austenitic stainless-steel castings in typical SCC environments such as seawater, brine, and chlorinated process media. It can operate stably for extended periods under conditions where traditional austenitic stainless-steel ANSI check valve frequently fail, greatly improving equipment reliability.

 

1.2 Excellent Resistance to Pitting and Crevice Corrosion

 

This advantage stems from its well-designed alloy composition: ASTM A995 Gr. 4A contains approximately 22% chromium (Cr), 3% molybdenum (Mo), and 0.10–0.30% nitrogen (N), achieving a pitting resistance equivalent (PREN) of 32–38, comparable to forged 2205 (UNS S32205) duplex steel and significantly higher than 316L castings (PREN≈25).

 

The synergistic effect of Mo and N is particularly crucial, giving it extremely strong resistance to pitting and crevice corrosion in neutral to weakly acidic media containing chloride ions (such as seawater and chloride solutions). It is especially suitable for complex casting structures with gaps, easily deposited media, and localized stagnation, such as ANSI check valve internal flow channels and flange sealing surfaces, reducing the risk of localized corrosion failure at its source.

 

1.3 Excellent Resistance to Uniform Corrosion

 

In neutral, weakly alkaline, and weakly acidic environments containing chloride ions, the high Cr content in ASTM A995 Gr. 4A ANSI check valve forms a stable passivation film with an extremely low overall uniform corrosion rate, far superior to ordinary carbon steel and low-alloy cast iron ANSI check valve. This effectively resists the overall erosion of the ANSI check valve body by chloride ions, extending the ANSI check valve's service life.

 

2. Precautions for Using ASTM A995 Gr. 4A ANSI check valve

 

2.1 Temperature Limitations

 

The recommended long-term operating temperature for this ANSI check valve is ≤300℃. Exceeding this temperature will significantly reduce the stability of its duplex structure, accelerate the precipitation of intermetallic phases, and significantly deteriorate its resistance to chloride ion corrosion. Especially under the combined conditions of "high temperature + high chloride," its corrosion resistance is far inferior to that of super duplex steel castings (such as ASTM A995 5A/6A) or nickel-based alloy castings, requiring material upgrades based on the specific operating conditions.

 

2.2 Concentration/Pressure Limitations

Use in extreme corrosive conditions should be avoided: Environments with extremely high concentrations of chloride ions, high temperature and pressure, or strong acidic chlorides (such as high-temperature concentrated hydrochloric acid, high-chlorine and high-pressure oil and gas) require careful consideration. ASTM A995 Gr. 4A ANSI check valve have insufficient resistance to pitting corrosion and SCC, making them prone to rapid corrosion failure. Appropriate selection based on operating conditions is necessary.

 

3. Core Differences Between ASTM A995 Gr. 4A and ASTM A182 F51 ANSI check valve

 

Both belong to the 2205 duplex stainless steel system. The core difference lies only in the manufacturing process and corresponding standards, as follows:

 

• ASTM A995 Gr. 4A: Follows the ASTM A995 standard and is a cast version of 2205 duplex stainless steel, primarily used for ANSI check valve components with complex structures (such as ANSI check valve bodies and covers).

 

• ASTM A182 F51: Follows the ASTM A182 standard and is a forged version of 2205 duplex stainless steel, emphasizing high strength and consistent performance. It is often used for ANSI check valve forgings with higher mechanical performance requirements.

 

4. Shortcomings of ASTM A995 Gr. 4A (Cast Version) Compared to ASTM A182 F51 (Forged Version)

 

4.1 Poor Performance Consistency and Microstructure Uniformity

The casting process has inherent limitations. During solidification, ASTM A995 Gr. 4A ANSI check valve are prone to defects such as component segregation, coarse grains, and localized porosity/venting. This leads to significant fluctuations in mechanical properties and corrosion resistance in different parts of the same batch or even the same ANSI check valve. Performance stability is far lower than that of the forged version of ASTM A182 F51 ANSI check valve. This shortcoming needs to be compensated for through rigorous heat treatment processes and non-destructive testing methods. 4.2 Slightly Inferior Low-Temperature Toughness and Plasticity

 

The elongation after fracture requirement for ASTM A995 Gr. 4A ANSI check valve is ≥20%, lower than that of forged ASTM A182 F51 ANSI check valve (≥25%). Its low-temperature toughness (especially for thick-section ANSI check valve) is more significantly affected by casting defects. If used in low-temperature conditions <-20℃, additional impact toughness verification is required, and the applicable low-temperature range is narrower than the forged version.

 

4.3 High Risk of Casting Defects and Strict Inspection Requirements

 

During the production process, this ANSI check valve is prone to casting defects such as shrinkage cavities, porosity, slag inclusions, and cold shuts. Since the ANSI check valve is a pressure-bearing component, mandatory non-destructive testing (UT), MT (magnetic particle testing), and PT (penetrating electrode testing) is required. The cost of defect detection and repair is high, and the overall failure rate is slightly higher than that of ASTM A182 F51 forged ANSI check valve.

 


Design Standard of 2205 Swing Check Valve (UNS S31803 Swing Check Valve):

Design Acc. to ASME B16.34 (ANSI Standard 2205 Swing Check Valve (UNS S31803 Swing Check Valve));

Design Acc. to EN-12516-1/2 (EN Standard 2205 Swing Check Valve (UNS S31803 Swing Check Valve), DIN Standard 2205 Swing Check Valve (UNS S31803 Swing Check Valve)).

 

Test Standard of 2205 Swing Check Valve (UNS S31803 Swing Check Valve):

Test Acc. to API 598 (ANSI Standard 2205 Swing Check Valve (UNS S31803 Swing Check Valve));

Test Acc. to EN 12266-1/2 (EN Standard 2205 Swing Check Valve (UNS S31803 Swing Check Valve), DIN Standard 2205 Swing Check Valve (UNS S31803 Swing Check Valve)).

 

Surface Finishing of 2205 Swing Check Valve (UNS S31803 Swing Check Valve):

All 2205 Swing Check Valve (UNS S31803 Swing Check Valve) surface is finely machined to achieve the required roughness and conforms to standard MSS SP-110.

 

Size of 2205 Swing Check Valve (UNS S31803 Swing Check Valve):

From DN1/4’’ to 48’’ (ANSI Standard 2205 Swing Check Valve (UNS S31803 Swing Check Valve));

From DN8 to DN1200 (EN Standard 2205 Swing Check Valve (UNS S31803 Swing Check Valve), DIN Standard 2205 Swing Check Valve (UNS S31803 Swing Check Valve)).

 

Face to Face of 2205 Swing Check Valve (UNS S31803 Swing Check Valve):

Face to Face Acc. to ASME B16.10 (ANSI Standard 2205 Swing Check Valve (UNS S31803 Swing Check Valve));

Face to Face Acc. to EN 558-1 (EN Standard 2205 Swing Check Valve (UNS S31803 Swing Check Valve), DIN Standard 2205 Swing Check Valve (UNS S31803 Swing Check Valve)).

 

Pressure Rating of 2205 Swing Check Valve (UNS S31803 Swing Check Valve):

ANSI Class 150 2205 Swing Check Valve (UNS S31803 Swing Check Valve) (ANSI Standard 2205 Swing Check Valve (UNS S31803 Swing Check Valve));

ANSI Class 300 2205 Swing Check Valve (UNS S31803 Swing Check Valve) (ANSI Standard 2205 Swing Check Valve (UNS S31803 Swing Check Valve));

ANSI Class 600 2205 Swing Check Valve (UNS S31803 Swing Check Valve) (ANSI Standard 2205 Swing Check Valve (UNS S31803 Swing Check Valve));

ANSI Class 800 2205 Swing Check Valve (UNS S31803 Swing Check Valve) (ANSI Standard 2205 Swing Check Valve (UNS S31803 Swing Check Valve));

ANSI Class 900 2205 Swing Check Valve (UNS S31803 Swing Check Valve) (ANSI Standard 2205 Swing Check Valve (UNS S31803 Swing Check Valve));

ANSI Class 1500 2205 Swing Check Valve (UNS S31803 Swing Check Valve) (ANSI Standard 2205 Swing Check Valve (UNS S31803 Swing Check Valve));

ANSI Class 2500 2205 Swing Check Valve (UNS S31803 Swing Check Valve) (ANSI Standard 2205 Swing Check Valve (UNS S31803 Swing Check Valve));

EN 1092 PN 16 2205 Swing Check Valve (UNS S31803 Swing Check Valve) (EN Standard 2205 Swing Check Valve (UNS S31803 Swing Check Valve), DIN Standard 2205 Swing Check Valve (UNS S31803 Swing Check Valve));

EN 1092 PN 25 2205 Swing Check Valve (UNS S31803 Swing Check Valve) (EN Standard 2205 Swing Check Valve (UNS S31803 Swing Check Valve), DIN Standard 2205 Swing Check Valve (UNS S31803 Swing Check Valve));

EN 1092 PN 40 2205 Swing Check Valve (UNS S31803 Swing Check Valve) (EN Standard 2205 Swing Check Valve (UNS S31803 Swing Check Valve), DIN Standard 2205 Swing Check Valve (UNS S31803 Swing Check Valve));

EN 1092 PN 63 2205 Swing Check Valve (UNS S31803 Swing Check Valve) (EN Standard 2205 Swing Check Valve (UNS S31803 Swing Check Valve), DIN Standard 2205 Swing Check Valve (UNS S31803 Swing Check Valve));

EN 1092 PN 100 2205 Swing Check Valve (UNS S31803 Swing Check Valve) (EN Standard 2205 Swing Check Valve (UNS S31803 Swing Check Valve), DIN Standard 2205 Swing Check Valve (UNS S31803 Swing Check Valve));

EN 1092 PN 160 2205 Swing Check Valve (UNS S31803 Swing Check Valve) (EN Standard 2205 Swing Check Valve (UNS S31803 Swing Check Valve), DIN Standard 2205 Swing Check Valve (UNS S31803 Swing Check Valve));

EN 1092 PN 250 2205 Swing Check Valve (UNS S31803 Swing Check Valve) (EN Standard 2205 Swing Check Valve (UNS S31803 Swing Check Valve), DIN Standard 2205 Swing Check Valve (UNS S31803 Swing Check Valve));

EN 1092 PN 320 2205 Swing Check Valve (UNS S31803 Swing Check Valve) (EN Standard 2205 Swing Check Valve (UNS S31803 Swing Check Valve), DIN Standard 2205 Swing Check Valve (UNS S31803 Swing Check Valve));

EN 1092 PN 400 2205 Swing Check Valve (UNS S31803 Swing Check Valve) (EN Standard 2205 Swing Check Valve (UNS S31803 Swing Check Valve), DIN Standard 2205 Swing Check Valve (UNS S31803 Swing Check Valve)).

 

Working Temperature of 2205 Swing Check Valve (UNS S31803 Swing Check Valve):

Please refer to the "Temperature and Pressure Curve of 2205 Swing Check Valve (UNS S31803 Swing Check Valve)" for temperature and pressure changes.

 

Ends Connection of 2205 Swing Check Valve (UNS S31803 Swing Check Valve):

ANSI Flange Ends 2205 Swing Check Valve (UNS S31803 Swing Check Valve);

ANSI Integral Flange Ends 2205 Swing Check Valve (UNS S31803 Swing Check Valve);

ANSI Welded Flange Ends 2205 Swing Check Valve (UNS S31803 Swing Check Valve);

Butt Weld (ASME B16.25) Ends 2205 Swing Check Valve (UNS S31803 Swing Check Valve);

Butt Weld x ANSI Flange Ends 2205 Swing Check Valve (UNS S31803 Swing Check Valve);

EN 1092 Flange Ends 2205 Swing Check Valve (UNS S31803 Swing Check Valve);

EN 1092 Integral Flange Ends 2205 Swing Check Valve (UNS S31803 Swing Check Valve);

EN 1092 Welded Flange Ends 2205 Swing Check Valve (UNS S31803 Swing Check Valve);

Butt Weld (EN 12627) Ends 2205 Swing Check Valve (UNS S31803 Swing Check Valve);

Butt Weld (ISO 1127) Ends 2205 Swing Check Valve (UNS S31803 Swing Check Valve);

Butt Weld x EN 1092 Flange Ends 2205 Swing Check Valve (UNS S31803 Swing Check Valve);

Male NPT (ASME B1.20.1) Ends 2205 Swing Check Valve (UNS S31803 Swing Check Valve);

Male BSPP (ISO 228-1) Ends 2205 Swing Check Valve (UNS S31803 Swing Check Valve);

Male BSPT (ISO 7-1) Ends 2205 Swing Check Valve (UNS S31803 Swing Check Valve);

Male NPT x Female NPT Ends 2205 Swing Check Valve (UNS S31803 Swing Check Valve);

Male BSPP x Female BSPP Ends 2205 Swing Check Valve (UNS S31803 Swing Check Valve);

Male BSPT x Female BSPT Ends 2205 Swing Check Valve (UNS S31803 Swing Check Valve);

Male NPT x Long Butt Weld (+100 mm) Ends 2205 Swing Check Valve (UNS S31803 Swing Check Valve);

Male BSPP x Long Butt Weld (+100 mm) Ends 2205 Swing Check Valve (UNS S31803 Swing Check Valve);

Male BSPT x Long Butt Weld (+100 mm) Ends 2205 Swing Check Valve (UNS S31803 Swing Check Valve);

Female NPT (ASME B1.20.1) Ends 2205 Swing Check Valve (UNS S31803 Swing Check Valve);

Female BSPP (ISO 228-1) Ends 2205 Swing Check Valve (UNS S31803 Swing Check Valve);

Female BSPT (ISO 7-1) Ends 2205 Swing Check Valve (UNS S31803 Swing Check Valve);

Socket Weld (ASME B16.11) Ends 2205 Swing Check Valve (UNS S31803 Swing Check Valve);

Socket Weld (EN 12760) Ends 2205 Swing Check Valve (UNS S31803 Swing Check Valve);

Female NPT x Socket Weld Ends 2205 Swing Check Valve (UNS S31803 Swing Check Valve);

Female BSPP x Socket Weld Ends 2205 Swing Check Valve (UNS S31803 Swing Check Valve);

Female BSPT x Socket Weld Ends 2205 Swing Check Valve (UNS S31803 Swing Check Valve);

Butt Weld (ASME B16.25) Ends 2205 Swing Check Valve (UNS S31803 Swing Check Valve);

Butt Weld (EN 12627) Ends 2205 Swing Check Valve (UNS S31803 Swing Check Valve);

Female NPT x Butt Weld Ends 2205 Swing Check Valve (UNS S31803 Swing Check Valve);

Female BSPP x Butt Weld Ends 2205 Swing Check Valve (UNS S31803 Swing Check Valve);

Female BSPT x Butt Weld Ends 2205 Swing Check Valve (UNS S31803 Swing Check Valve);

Female NPT x Long Butt Weld (+100 mm) Ends 2205 Swing Check Valve (UNS S31803 Swing Check Valve);

Female BSPP x Long Butt Weld (+100 mm) Ends 2205 Swing Check Valve (UNS S31803 Swing Check Valve);

Female BSPT x Long Butt Weld (+100 mm) Ends 2205 Swing Check Valve (UNS S31803 Swing Check Valve);

Long Butt Weld (+100 mm Weld Stub) Ends 2205 Swing Check Valve (UNS S31803 Swing Check Valve).

 

CE Marking of 2205 Swing Check Valve (UNS S31803 Swing Check Valve):

CE Marking is Available to 2205 Swing Check Valve (UNS S31803 Swing Check Valve) with a Diameter of DN32 or Larger.

 

Chemical Composition of 2205 Swing Check Valve (UNS S31803 Swing Check Valve):

For the Chemical Composition of 2205 Swing Check Valve (UNS S31803 Swing Check Valve), please refer to EN 10204 Type 3.1 certificate.

 

Mechanical Properties of 2205 Swing Check Valve (UNS S31803 Swing Check Valve):

For the Mechanical Properties of 2205 Swing Check Valve (UNS S31803 Swing Check Valve), please refer to EN 10204 Type 3.1 certificate.

 

Certificate of 2205 Swing Check Valve (UNS S31803 Swing Check Valve):

All 2205 Swing Check Valve (UNS S31803 Swing Check Valve) will be delivered with EN 10204 Type 3.1 Certificate.

 

Approvals of 2205 Swing Check Valve (UNS S31803 Swing Check Valve):

MSS SP-110 Certified of 2205 Swing Check Valve (UNS S31803 Swing Check Valve);

NACE MR 0175 Certified of 2205 Swing Check Valve (UNS S31803 Swing Check Valve)

API 607 Fire Safe Certified of 2205 Swing Check Valve (UNS S31803 Swing Check Valve);

ISO 9001 Certified of 2205 Swing Check Valve (UNS S31803 Swing Check Valve);

PED Certified of 2205 Swing Check Valve (UNS S31803 Swing Check Valve).

 

Available Upon Request of 2205 Swing Check Valve (UNS S31803 Swing Check Valve):

NACE MR0175 is available upon request of 2205 Swing Check Valve (UNS S31803 Swing Check Valve);

ATEX is available upon request of 2205 Swing Check Valve (UNS S31803 Swing Check Valve);

TA-LUFT is available upon request of 2205 Swing Check Valve (UNS S31803 Swing Check Valve);

SIL is available upon request of 2205 Swing Check Valve (UNS S31803 Swing Check Valve);

Degreasing is available upon request of 2205 Swing Check Valve (UNS S31803 Swing Check Valve);

Fire Safe is available upon request of 2205 Swing Check Valve (UNS S31803 Swing Check Valve);

Stem Extension is available upon request of 2205 Swing Check Valve (UNS S31803 Swing Check Valve);

Double Block and Bleed is available upon request of 2205 Swing Check Valve (UNS S31803 Swing Check Valve).

 


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