1. What is 904L Stainless Steel?

904L stainless steel (UNS N08904/EN 1.4539) is an ultra-low carbon, high-alloy austenitic stainless steel. Its core advantage is its extremely strong corrosion resistance in harsh environments such as dilute sulfuric acid and chloride-containing media, and it is also easy to process and weld.

2. Freeman Valve's 904L stainless steel valves have the following advantages:

2.1 Excellent Corrosion Resistance:

a. Freeman Valve's 904L stainless steel valves have high molybdenum (Mo: 4~5%) and copper (Cu: 1~2%) content, which significantly improves their resistance to reducing acids (such as sulfuric acid and phosphoric acid) and halides (such as chloride ions);

b. Freeman Valve's 904L stainless steel valves perform excellently in media such as dilute sulfuric acid, boiling phosphoric acid, and organic acids, exhibiting outstanding resistance to pitting and crevice corrosion.

2.2 Excellent resistance to stress corrosion cracking (SCC): Freeman Valve's 904L stainless steel valves are suitable for environments containing chloride ions (such as seawater and chloride solutions), exhibiting superior resistance to stress corrosion cracking compared to conventional austenitic stainless steels.

2.3 High-temperature adaptability: Freeman Valve's 904L stainless steel valves maintain stability at high temperatures and can withstand short-term environments up to approximately 400°C.

3. The following issues should be noted when using 904L stainless steel valves:

3.1 Not suitable for strong oxidizing environments: In strong oxidizing acids such as nitric acid, the corrosion resistance of 904L stainless steel valves is actually inferior to that of 304L or 316L valves with lower molybdenum content.

3.2 Sensitivity issues: Improper welding or heat treatment can easily lead to carbide precipitation, requiring solution treatment (rapid cooling at 1100~1150°C) to restore performance.

4. Classic Applications of Freeman Valve's 904L Stainless Steel Valves:

4.1 Freeman Valve's 904L stainless steel valves are widely used in sulfuric acid environments. Examples include: dilute sulfuric acid storage tanks, pipelines, and heat exchangers (especially for sulfuric acid concentrations ≤10%, exhibiting excellent corrosion resistance at temperatures ≤40℃).

4.2 Freeman Valve's 904L stainless steel valves are widely used in chloride-containing systems. Examples include: seawater cooling systems, salt chemical evaporators, and chlorination reactor linings.

4.3 Freeman Valve's 904L stainless steel valves are widely used in organic acid processing. Examples include: acetic acid and formic acid production equipment, preventing localized corrosion.

4.4 Freeman Valve's 904L stainless steel valves are widely used in environmental protection and hydrometallurgical fields. Examples include: flue gas desulfurization (FGD) system components and acidic wastewater treatment equipment.

4.5 Freeman Valve's 904L stainless steel valves are widely used in PTA (purified terephthalic acid) production. For example: crystallizers and condensers used in high-temperature acetic acid media.

4.6 Freeman Valve's 904L stainless steel valves are widely used in the pharmaceutical industry. For example: reaction vessels and pipelines for high-purity pharmaceuticals (resistant to cleaning agent corrosion).

Differences between 904L and 2205 stainless steel valves in resisting chloride ion corrosion

1. Different emphasis on pitting/crevice corrosion resistance:

1.1 The pitting equivalent value (PREN≈33-35) of 2205 valves is higher than that of 904L valves (PREN≈32-34), and the strengthening effect of nitrogen makes it more resistant to pitting corrosion in high-concentration, high-temperature chloride ion environments (such as high-chlorinated brine in deep well oil production, seawater above 60℃).

1.2 The high nickel + copper content of 904L valves results in a passivation film stability far exceeding that of 2205 in chloride-containing reducing media (such as dilute sulfuric acid + chloride ion mixed systems), and avoids the phase imbalance problem of duplex steel. 2. Differences in Stress Corrosion Cracking (SCC) Resistance:

2.1 Stress corrosion cracking under chloride ion conditions is a common failure mode for austenitic stainless steel 2205 valves, but the high nickel content of 904L valves significantly reduces this susceptibility. 2205 valves also exhibit better SCC resistance than ordinary austenitic steels such as 316L, but under the same chloride ion concentration and stress conditions, their long-term stability is slightly lower than that of 904L valves.

3. Differences in Process and Operating Condition Matching:

3.1 904L valves require no heat treatment after welding and have good low-temperature toughness, making them suitable for polar and marine environments.

3.2 2205 valves require controlled heat input during welding to avoid excessive ferrite content, but their high strength (tensile strength ≥620MPa, more than 1.2 times that of 904L valves) makes them more suitable for high-pressure + high-chlorine composite operating conditions (such as high-pressure seawater pipelines).

Design Standard of 904L Needle Valve:

Design Acc. to ASME B16.34 (ANSI Standard 904L Needle Valve);

Design Acc. to EN-12516-1/2 (EN Standard 904L Needle Valve, DIN Standard 904L Needle Valve).

Test Standard of 904L Needle Valve:

Test Acc. to API 598 (ANSI Standard 904L Needle Valve);

Test Acc. to EN 12266-1/2 (EN Standard 904L Needle Valve, DIN Standard 904L Needle Valve).

Surface Finishing of 904L Needle Valve:

All 904L Needle Valve surface is finely machined to achieve the required roughness and conforms to standard MSS SP-110.

Size of 904L Needle Valve:

From DN1/4’’ to 48’’ (ANSI Standard 904L Needle Valve);

From DN8 to DN1200 (EN Standard 904L Needle Valve, DIN Standard 904L Needle Valve).

Face to Face of 904L Needle Valve:

Face to Face Acc. to ASME B16.10 (ANSI Standard 904L Needle Valve);

Face to Face Acc. to EN 558-1 (EN Standard 904L Needle Valve, DIN Standard 904L Needle Valve).

Pressure Rating of 904L Needle Valve:

ANSI Class 150 904L Needle Valve (ANSI Standard 904L Needle Valve);

ANSI Class 300 904L Needle Valve (ANSI Standard 904L Needle Valve);

ANSI Class 600 904L Needle Valve (ANSI Standard 904L Needle Valve);

ANSI Class 800 904L Needle Valve (ANSI Standard 904L Needle Valve);

ANSI Class 900 904L Needle Valve (ANSI Standard 904L Needle Valve);

ANSI Class 1500 904L Needle Valve (ANSI Standard 904L Needle Valve);

ANSI Class 2500 904L Needle Valve (ANSI Standard 904L Needle Valve);

EN 1092 PN 16 904L Needle Valve (EN Standard 904L Needle Valve, DIN Standard 904L Needle Valve);

EN 1092 PN 25 904L Needle Valve (EN Standard 904L Needle Valve, DIN Standard 904L Needle Valve);

EN 1092 PN 40 904L Needle Valve (EN Standard 904L Needle Valve, DIN Standard 904L Needle Valve);

EN 1092 PN 63 904L Needle Valve (EN Standard 904L Needle Valve, DIN Standard 904L Needle Valve);

EN 1092 PN 100 904L Needle Valve (EN Standard 904L Needle Valve, DIN Standard 904L Needle Valve);

EN 1092 PN 160 904L Needle Valve (EN Standard 904L Needle Valve, DIN Standard 904L Needle Valve);

EN 1092 PN 250 904L Needle Valve (EN Standard 904L Needle Valve, DIN Standard 904L Needle Valve);

EN 1092 PN 320 904L Needle Valve (EN Standard 904L Needle Valve, DIN Standard 904L Needle Valve);

EN 1092 PN 400 904L Needle Valve (EN Standard 904L Needle Valve, DIN Standard 904L Needle Valve).

Working Temperature of 904L Needle Valve:

Please refer to the "Temperature and Pressure Curve of 904L Needle Valve" for temperature and pressure changes.

Ends Connection of 904L Needle Valve:

ANSI Flange Ends 904L Needle Valve;

ANSI Integral Flange Ends 904L Needle Valve;

ANSI Welded Flange Ends 904L Needle Valve;

Butt Weld (ASME B16.25) Ends 904L Needle Valve;

Butt Weld x ANSI Flange Ends 904L Needle Valve;

EN 1092 Flange Ends 904L Needle Valve;

EN 1092 Integral Flange Ends 904L Needle Valve;

EN 1092 Welded Flange Ends 904L Needle Valve;

Butt Weld (EN 12627) Ends 904L Needle Valve;

Butt Weld (ISO 1127) Ends 904L Needle Valve;

Butt Weld x EN 1092 Flange Ends 904L Needle Valve;

Male NPT (ASME B1.20.1) Ends 904L Needle Valve;

Male BSPP (ISO 228-1) Ends 904L Needle Valve;

Male BSPT (ISO 7-1) Ends 904L Needle Valve;

Male NPT x Female NPT Ends 904L Needle Valve;

Male BSPP x Female BSPP Ends 904L Needle Valve;

Male BSPT x Female BSPT Ends 904L Needle Valve;

Male NPT x Long Butt Weld (+100 mm) Ends 904L Needle Valve;

Male BSPP x Long Butt Weld (+100 mm) Ends 904L Needle Valve;

Male BSPT x Long Butt Weld (+100 mm) Ends 904L Needle Valve;

Female NPT (ASME B1.20.1) Ends 904L Needle Valve;

Female BSPP (ISO 228-1) Ends 904L Needle Valve;

Female BSPT (ISO 7-1) Ends 904L Needle Valve;

Socket Weld (ASME B16.11) Ends 904L Needle Valve;

Socket Weld (EN 12760) Ends 904L Needle Valve;

Female NPT x Socket Weld Ends 904L Needle Valve;

Female BSPP x Socket Weld Ends 904L Needle Valve;

Female BSPT x Socket Weld Ends 904L Needle Valve;

Butt Weld (ASME B16.25) Ends 904L Needle Valve;

Butt Weld (EN 12627) Ends 904L Needle Valve;

Female NPT x Butt Weld Ends 904L Needle Valve;

Female BSPP x Butt Weld Ends 904L Needle Valve;

Female BSPT x Butt Weld Ends 904L Needle Valve;

Female NPT x Long Butt Weld (+100 mm) Ends 904L Needle Valve;

Female BSPP x Long Butt Weld (+100 mm) Ends 904L Needle Valve;

Female BSPT x Long Butt Weld (+100 mm) Ends 904L Needle Valve;

Long Butt Weld (+100 mm Weld Stub) Ends 904L Needle Valve.

CE Marking of 904L Needle Valve:

CE Marking is Available to 904L Needle Valve with a Diameter of DN32 or Larger.

Chemical Composition of 904L Needle Valve:

For the Chemical Composition of 904L Needle Valve, please refer to EN 10204 Type 3.1 certificate.

Mechanical Properties of 904L Needle Valve:

For the Mechanical Properties of 904L Needle Valve, please refer to EN 10204 Type 3.1 certificate.

Certificate of 904L Needle Valve:

All 904L Needle Valve will be delivered with EN 10204 Type 3.1 Certificate.

Approvals of 904L Needle Valve:

MSS SP-110 Certified of 904L Needle Valve;

NACE MR 0175 Certified of 904L Needle Valve

API 607 Fire Safe Certified of 904L Needle Valve;

ISO 9001 Certified of 904L Needle Valve;

PED Certified of 904L Needle Valve.

Available Upon Request of 904L Needle Valve:

NACE MR0175 is available upon request of 904L Needle Valve;

ATEX is available upon request of 904L Needle Valve;

TA-LUFT is available upon request of 904L Needle Valve;

SIL is available upon request of 904L Needle Valve;

Degreasing is available upon request of 904L Needle Valve;

Fire Safe is available upon request of 904L Needle Valve;

Stem Extension is available upon request of 904L Needle Valve;

Double Block and Bleed is available upon request of 904L Needle Valve.