304/304L Stainless Steel Flanges

Corrosion Resistance: Excellent resistance to oxidation and corrosion in fresh water, mild chemical media, and atmospheric conditions. The 304L grade provides additional protection against intergranular corrosion after welding.

Weldability and Formability: The low carbon content of 304L prevents carbide precipitation during welding; flanges are suitable for all standard welding processes including TIG, MIG, and stick welding.

Full Range of Types: Weld neck (WN), slip-on (SO), blind (BL), socket weld (SW), threaded (TH), lap joint (LJ), plate flanges, and orifice flanges.

Pressure Ratings: Available in Class 150, 300, 600, 900, 1500, and 2500 (PN6 to PN400 in metric equivalents).

Mechanical Strength: Good tensile and yield strength combined with excellent ductility, suitable for moderate-pressure pipelines and structural bolted connections.

Excellent Formability: 304/304L stainless steel offers superior forming characteristics, making it ideal for complex flange geometries and custom configurations.

Cost-Effective Solution: Lower alloy content (no molybdenum) compared to 316/316L makes 304/304L a more economical choice for applications where chloride-induced pitting is not a concern.

International Certifications: Flanges can be certified by ABS, BV, DNV, LR, GL, RINA, CCS, KR, and NK, and comply with NORSOK, PED, and ASME standards for global projects.

These standards ensure that our 304/304L stainless steel flanges meet global requirements for chemical composition, mechanical properties, dimensional tolerances, and pressure-temperature ratings.

The lower carbon content in 304L minimizes carbide precipitation during welding, providing enhanced resistance to intergranular corrosion compared to standard 304, especially in welded service environments.

Heat Treatment Condition:
All flanges are solution annealed at 1010–1080°C followed by rapid cooling (water quenching or rapid air cooling). This treatment restores full corrosion resistance, relieves internal stresses from forging, and enhances ductility, ensuring reliable performance in general industrial, food processing, and moderate chemical service.

Delivery Condition: Flanges normally supplied in solution annealed and pickled condition, providing a clean, smooth surface and excellent corrosion resistance.

Reference: ASME B16.5 – 304 stainless steel. For 304L the ratings are identical. Maximum continuous service temperature is 800°C (1472°F).

Standard Dimensions: ASME B16.5 for sizes up to 24″, and ASME B16.47 Series A/B for large diameters up to 60″. EN 1092-1 dimensions available upon request.

Raw Material Selection: High-quality 304/304L stainless steel bars or billets from certified mills (Baosteel, TISCO, POSCO, Outokumpu) with certified chemical composition and traceability.

Cutting & Heating: Material is cut to precise weight using band saws or shearing equipment, then induction-heated to forging temperature (1100–1200°C).

Forging: Hot forged using hydraulic presses (3000–8000 tons) or hammer forging to shape the flange blank. Multiple forging steps ensure grain flow optimization.

Heat Treatment: Solution annealing at 1010–1080°C followed by rapid cooling (water quenching or rapid air cooling) to restore corrosion resistance and ductility.

Machining: CNC lathes and milling machines produce precise dimensions, bolt holes, and facing surfaces. Common operations include facing, boring, drilling bolt holes, and groove cutting for RTJ.

Surface Finishing: Raised face serration, flat facing, or RTJ groove machining per ASME B16.5 requirements.

Marking: Laser engraving or stamping with grade (304/304L), size (NPS), class, heat number, manufacturer identification, and standard.

Inspection & Testing: Dimensional check, PMI, hardness test, and NDT as required.

Surface Treatment: Pickling, passivation, or rust preventive oil coating to protect against corrosion.

Chemical Analysis: Positive Material Identification (PMI) 100% verification using handheld XRF spectrometer.

Mechanical Testing: Tensile strength, yield strength, elongation, and hardness per ASTM A370.

Dimensional Inspection: OD, ID, bolt circle, bolt hole alignment, thickness, flatness using calibrated gauges and CMM.

Thread Inspection: NPT thread verification using GO/NO-GO gauges per ANSI B1.20.1.

NDT – Liquid Penetrant Testing (PT): 100% for surface defects.

NDT – Ultrasonic Testing (UT): For internal flaws upon request.

Intergranular Corrosion Test: ASTM A262 Practice E for 304L.

Third-Party Inspection: SGS, BV, DNV, TUV, LR, or ABS on customer request.

Chemical & Petrochemical (Mild Service): Non-chloride acid transfer lines, organic chemical piping, solvent systems.

Marine & Offshore (Limited): Fresh water and brackish water systems, firefighting lines, accommodation piping (ABS/BV/DNV/LR certified available).

Pharmaceutical Equipment: Clean steam systems, water-for-injection (WFI) distribution, sanitary process lines.

Food & Beverage Industry: Dairy processing lines, brewery piping, pasteurizer connections, fruit juice processing.

Power Generation: Auxiliary cooling water, condensate return lines, low-pressure steam systems.

Water Treatment: Reverse osmosis feed lines, demineralized water distribution.

HVAC & Refrigeration: Chilled water lines, condenser water piping.

Construction & Infrastructure: Handrails, structural supports, architectural piping.

Pulp & Paper: White water systems, non-corrosive process streams.

Small flanges (≤4″): Heavy-duty cartons with moisture barrier paper on pallets.
Medium flanges (6″–12″): Wooden crates with foam padding dividers, VCI paper wrapping.
Large flanges (≥14″): Individual wooden crates or steel-framed pallets with foam padding.

All shipments: Rust preventive oil coating, individual tagging (grade, size, class, heat number), waterproof shipping marks.

Womic Steel’s Delivery Strengths:                                            

Ready stock: Class 150 and 300 flanges in sizes 1/2″–24″ – dispatch within 24 hours.

Direct cooperation with global shipowners for competitive freight.

Professional loading by in-house teams.

Complete documentation for customs clearance.

1. What is the difference between 304 and 304L flanges?
304L has lower carbon (≤0.03%), preventing carbide precipitation during welding. For welded flange joints exposed to 425–870°C, 304L is preferred.

2. Can 304 flanges be used in seawater?
No. For marine applications, use 316L, duplex 2205, or super duplex 2507 flanges.

3. What is the maximum temperature for 304L flanges?
Continuous service: 800°C (1472°F). Intermittent service: 850°C (1562°F).

4. Do you provide material test reports?
Yes. EN 10204 3.1 MTR included. Third-party inspection available.

5. Are your flanges suitable for food processing?
Yes, with electropolished or high-polish (≤32 μinch) finish for food contact surfaces.

Complete Product Range: All flange types and pressure classes – one-stop sourcing.

Strict Quality Control: ISO 9001, PED 2014/68/EU, API Q1 certified.

Advanced Forging & Machining: Modern CNC equipment and heat treatment furnaces.

Full Traceability: Heat number stamped – traceable to raw material.

Flexible Customization: Special sizes, facings, or non-standard materials.

Global Delivery: Exported to over 50 countries.

Tel / WhatsApp:

Victor: +86 15575100681

Jack: +86 18390957568

E-mail: info@womicstainless.com

Website: www.womicsteel.com

Contact Womic Steel today for a competitive quote on 304/304L stainless steel flanges. We offer certified quality, fast production lead times, and reliable global delivery to keep your pipeline projects running smoothly.

Stock Examples (Class 150 WN RF – 304/304L):

1/2″ (DN15) × Sch40S

2″ (DN50) × Sch40S

4″ (DN100) × Sch10S

6″ (DN150) × Sch40S

12″ (DN300) × Sch80S

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