304 Neck Butt Welding Flange

Technical Specifications

1. Material Certification (ASTM A182 F304)

Element Standard Value Function Test Case

Ni 8.0~11.0% Austenite Stability 9.2%

C ≤0.08% - 0.05%

Cr 18.0~20.0% Oxidation Corrosion Protection 18.8% (Spectrometer)

2. Pressure-Temperature

Temperature (°C) Class 150 (bar) Class 300 (bar)

300 13.2 35.8

200 15.8 42.7

38 19.6 51.1

3. Mechanical Properties

Parameter 304 Flange Value Standard Basis

Inner Diameter Tolerance (NPS 12") ±0.25mm ASME B16.5 Table5

Tensile Strength 515 MPa ASTM A182

Yield Strength 205 MPa ASTM A182

Bolt hole center circle deviation ±0.8mm MSS SP-44

Applicable scenarios

Recommended scenarios Tolerable media Prohibited scenarios Alternative solutions

Low-pressure compressed air Dry air (dew point <-40°C) Sulfur-containing humid air Nickel-plated carbon steel

Food equipment Dairy products, juice (pH>4.5) Chlorine-containing disinfectants 316L flange

Municipal water supply Fresh water, drinking water Seawater/high chlorine water (>50ppm Cl⁻) 316 flange

HVAC Hot water (<80°C), steam Hydrochloric acid/sulfuric acid (pH<4) Hastelloy alloy

Why choose 304 Neck Butt Welding Flange?

1. Lower cost

Material Unit price (benchmark) Service life Comprehensive cost (10 years)

316 flange 2.3x 15 years + 1.2x

304 Neck Butt Welding Flange 1.6x 10 years + 1.0x

Carbon steel flange 1.0x 2 years (Rust leakage) 2.8x

2. Structural design advantages

Sealing surface accuracy: RF surface roughness of 304 stainless steel neck welding flange is 125-250μin Ra, ensuring the reliability of gasket sealing.

Tapered neck transition: Reduce stress concentration factor by 40% and extend weld fatigue life.

3. Basic corrosion resistance

Salt spray test: No red rust for 500 hours

Chromium-nickel protective layer: Cr content ≥18% forms a passivation film to resist corrosion from water, steam, and weak acid (pH>4.5).

Limitation description: Not suitable for environments containing chloride ions>50ppm (such as seawater), and 316 needs to be upgraded at this time.

FAQ

Q1: What is the cost difference with 316 flange?

Answer: The price of 304 Neck Butt Welding Flange is 30~35% lower under the same specifications (due to the difference in nickel and molybdenum content). If the medium does not contain chloride ions/acids, it is more economical to choose 304.

Q2: Can 304 be used for outdoor pipes?

Answer: In low humidity (<60%) RH) It can be used for a long time in a salt-free environment; anti-corrosion coating is required in coastal/industrial areas, otherwise pitting may occur within 2-3 years.