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WN Flange
SDFL
The 321 stainless steel WNRF (weld neck, raised face) flange is a forged pipe flange produced for steam and high-temperature process piping. It is manufactured to ASME B16.5 dimensions in Class 300, with a tapered hub that is butt-welded to the matching pipe. The raised-face sealing surface is used with gaskets selected for the design temperature, pressure, and medium, such as spiral-wound gaskets.
The tapered hub transfers the wall thickness of the pipe into the flange ring and provides a gradual transition for loads and thermal movement. The hub end is prepared for a full-penetration butt weld, which allows the weld to be examined by the nondestructive testing method specified in the project code.
The raised face concentrates gasket pressure over a smaller contact area. Class 300 is a pressure class rather than a fixed working pressure; allowable pressure decreases as temperature rises, so the rating must be selected from the ASME B16.5 pressure-temperature tables for the specified material group and design temperature.
The flange is forged from ASTM A182 Grade F321 (UNS S32100, EN 1.4541), a titanium-stabilized austenitic stainless steel. Titanium combines with carbon to form titanium carbides, which reduces chromium-carbide precipitation at grain boundaries during exposure in the 427-816 °C (800-1500 °F) range. Grade F347, which is niobium-stabilized, can be supplied as an alternative when specified.
Flange dimensions follow ASME B16.5; parts can also be supplied to EN 1092-1, JIS B2220, GOST 12821, or customer drawings. Each batch is delivered with a material test report per EN 10204 3.1, and PMI testing can be arranged before shipment.
Item | Details |
|---|---|
FLANGE TYPE | Standard: WNRF Weld Neck Flange; other flange types available upon request |
SIZE RANGE | Standard: NPS 1/2" – NPS 24" (DN15 – DN100) to ASME B16.5; Custom sizes available per customer drawing |
PRESSURE | Class 150 – 2500, PN0.6 – PN400, 5K – 40K |
SEALING FACE | RF, FF, RTJ, Tongue & Groove, customizable |
STANDARDS | ASME B16.5, EN 1092-1, DIN, JIS B2220, GOST 12821, GB/T 9124.1-2019, custom standards |
MATCHED PIPE SCHEDULE | SCH5S – SCH160 |
MATERIAL | Standard: ASTM A182 F321 (UNS S32100 / EN 1.4541) Optional: F304/F304L, F316/F316L, F321, F347, duplex steel, nickel alloys, carbon stee |
SURFACE TREATMENT | Pickling & Passivation, As-machined, Mechanical Polishing, Electropolishing (EP) |
Applications | Petrochemical, pharmaceutical, power plants, shipbuilding, water treatment, general industrial piping |
The table below reproduces the ANSI B16.5 Class 300 flange dimensions shown in the reference table; all values are in inches.
Nom. Pipe Size | O | T | R | X | No./Dia. of Holes | Bolt Circle Dia | L2 | H | B2 | L | B | r | L3 | B3 | D | C | Thr |
1/2 | 3.75 | 0.56 | 1.38 | 1.5 | 4-0.62 | 2.62 | 2.06 | 0.84 | 0.62 | 0.88 | 0.88 | 0.12 | 0.88 | 0.90 | 0.38 | 0.93 | 0.62 |
3/4 | 4.62 | 0.62 | 1.69 | 1.88 | 4-0.75 | 3.25 | 2.25 | 1.05 | 0.82 | 1.00 | 1.09 | 0.12 | 1.00 | 1.11 | 0.44 | 1.14 | 0.62 |
1 | 4.88 | 0.69 | 2.00 | 2.12 | 4-0.75 | 3.50 | 2.44 | 1.32 | 1.05 | 1.06 | 1.36 | 0.12 | 1.06 | 1.38 | 0.50 | 1.41 | 0.69 |
1-1/4 | 5.25 | 0.75 | 2.50 | 2.50 | 4-0.75 | 3.88 | 2.56 | 1.66 | 1.38 | 1.06 | 1.70 | 0.19 | 1.06 | 1.72 | 0.56 | 1.75 | 0.81 |
1-1/2 | 6.12 | 0.81 | 2.88 | 2.75 | 4-0.88 | 4.50 | 2.69 | 1.90 | 1.61 | 1.19 | 1.95 | 0.25 | 1.19 | 1.97 | 0.62 | 1.99 | 0.88 |
2 | 6.50 | 0.88 | 3.62 | 3.31 | 8-0.75 | 5.00 | 2.75 | 2.38 | 2.07 | 1.31 | 2.44 | 0.31 | 1.31 | 2.46 | 0.69 | 2.50 | 1.12 |
2-1/2 | 7.50 | 1.00 | 4.12 | 3.94 | 8-0.88 | 5.88 | 3.00 | 2.88 | 2.47 | 1.50 | 2.94 | 0.31 | 1.50 | 2.97 | 0.75 | 3.00 | 1.25 |
3 | 8.25 | 1.12 | 5.00 | 4.62 | 8-0.88 | 6.62 | 3.12 | 3.50 | 3.07 | 1.69 | 3.57 | 0.38 | 1.69 | 3.60 | 0.81 | 3.63 | 1.25 |
3-1/2 | 9.00 | 1.19 | 5.50 | 5.25 | 8-0.88 | 7.25 | 3.19 | 4.00 | 3.55 | 1.75 | 4.07 | 0.38 | 1.75 | 4.10 | / | 4.13 | 1.44 |
4 | 10.00 | 1.25 | 6.19 | 5.75 | 8-0.88 | 7.88 | 3.38 | 4.50 | 4.03 | 1.88 | 4.57 | 0.44 | 1.88 | 4.60 | / | 4.63 | 1.44 |
5 | 11.00 | 1.38 | 7.31 | 7.00 | 8-0.88 | 9.25 | 3.88 | 5.56 | 5.05 | 2.00 | 5.66 | 0.44 | 2.00 | 5.69 | / | 5.69 | 1.69 |
6 | 12.50 | 1.44 | 8.50 | 8.12 | 12-0.88 | 10.62 | 3.88 | 6.63 | 6.07 | 2.06 | 6.72 | 0.50 | 2.06 | 6.75 | / | 6.75 | 1.81 |
8 | 15.00 | 1.62 | 10.62 | 10.25 | 12-1.00 | 13.00 | 4.38 | 8.63 | 7.98 | 2.44 | 8.72 | 0.50 | 2.44 | 8.75 | / | 8.75 | 2.00 |
10 | 17.50 | 1.88 | 12.75 | 12.62 | 16-1.12 | 15.25 | 4.62 | 10.75 | 10.02 | 2.62 | 10.88 | 0.50 | 3.75 | 10.92 | / | 10.88 | 2.19 |
12 | 20.50 | 2.00 | 15.00 | 14.75 | 16-1.25 | 17.75 | 5.12 | 12.75 | 12.00 | 2.88 | 12.88 | 0.50 | 4.00 | 12.92 | / | 12.94 | 2.38 |
14 | 23.00 | 2.12 | 16.25 | 16.75 | 20-1.25 | 20.25 | 5.62 | 14.00 | 13.25 | 3.00 | 14.14 | 0.50 | 4.38 | 14.18 | / | 14.19 | 2.50 |
16 | 25.50 | 2.25 | 18.50 | 19.00 | 20-1.38 | 22.50 | 5.75 | 16.00 | 15.25 | 3.25 | 16.16 | 0.50 | 4.75 | 16.19 | / | 16.19 | 2.69 |
18 | 28.00 | 2.38 | 21.00 | 21.00 | 24-1.38 | 24.75 | 6.25 | 18.00 | 17.25 | 3.50 | 18.18 | 0.50 | 5.12 | 18.20 | / | 18.19 | 2.75 |
20 | 30.50 | 2.50 | 23.00 | 23.12 | 24-1.38 | 27.00 | 6.38 | 20.00 | 19.25 | 3.75 | 20.20 | 0.50 | 5.50 | 20.25 | / | 20.19 | 2.88 |
22 | 33.00 | 2.63 | 25.25 | 25.25 | 24-1.63 | 29.25 | 6.50 | 22.00 | 21.25 | 4.00 | 22.22 | 0.50 | 5.75 | 22.25 | / | 22.19 | 3.13 |
24 | 36.00 | 2.75 | 27.25 | 27.62 | 24-1.62 | 32.00 | 6.62 | 24.00 | 23.25 | 4.19 | 24.25 | 0.50 | 6.00 | 24.25 | / | 24.19 | 3.25 |
Forgings are closed-die forged, solution-annealed, and CNC-machined. The raised face is machined to the specified surface finish, and the bore and hub end are prepared for butt welding. Inspection includes dimensional verification and visual and surface examination. Radiographic, ultrasonic, or liquid-penetrant testing and third-party inspection can be arranged when specified on the order.
1. Raw Material PMI Spectral Inspection
2. Closed-die Hot Forging (Hydraulic Forming Press)
3. Solution Heat Treatment (Continuous Heat Treatment Line)
4. Precision CNC Machining (5-axis Machining Center, High-precision CNC Lathe)
5. Semi-finishing Dimensional & Surface Inspection
6. Surface Finishing (Pickling & Passivation / Mechanical / Electropolishing)
7. Final Quality Control (Dimensional Test, NDT, Surface Defect Check)
8. Export Standard Packaging
9. Delivery
Typical services include steam distribution lines in thermal power plants, district heating networks, high-temperature heat-transfer-oil circuits, high-temperature process-gas and flue-gas lines, and pressure-vessel nozzles. Material selection should be confirmed against the design temperature, pressure, and medium by the purchaser's engineering team.
Available options include other face types (FF, RTJ, tongue-and-groove), Class 150-2500 ratings, non-standard sizes, additional heat treatment, traceability marking, and third-party inspection. Non-standard parts can be produced from customer drawings or samples.
Material Verification: 100% PMI spectral analysis, chemical composition fully traceable to original mill melt number
Dimensional Control: High-precision dimension inspection, strict tolerance compliance with international standards
Non-destructive Testing: Penetrant test, ultrasonic test, radiographic test available on request
Surface & Cleanliness: Surface defect inspection; sanitary grade electrolytic polishing & cleanliness test
Third-party Inspection: SGS, BV, TUV witnessed inspection supported
16+ Years Professional Manufacturer (Founded in 2010, based in Wenzhou, China)
Full In-house Production Chain: Forging → Heat Treatment → CNC Machining → Testing
Leading Special Alloy Technology: Mature processing of nickel-based, Hastelloy, super austenitic and super duplex steel
Dual Product System: Industrial heavy-duty flanges + Sanitary high-purity flanges
Complete Authoritative Certifications: TS pressure pipe license, ISO 9001/14001/45001, CE-PED, AD2000, EAC
Full Engineering Support: Working condition analysis, material selection, custom solution design
New Energy Layout: Professional piping solutions for data center liquid cooling, hydrogen energy and energy storage
Stable & Reliable Delivery: exported to 30+ countries
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F321 is titanium-stabilized, which reduces sensitization in the 427-816 °C range. Unstabilized grades may be sensitized after prolonged exposure in this range, depending on carbon content and exposure time.
F321 weldments commonly do not require post-weld solution treatment for standard service. Requirements for a specific application should be checked against the applicable code and project specification.
Standard-size flanges held in stock can be shipped within 3-5 working days. Custom production typically takes 8-15 working days, depending on size, quantity, and inspection requirements.
ASME B16.5 flanges are supplied from NPS 1/2 through NPS 24. Larger diameters are manufactured to ASME B16.47 or customer drawings.
Each shipment includes an EN 10204 3.1 material test report. NDT reports, PMI reports, and third-party certificates can be provided when specified on the order.
If a product does not conform to the agreed specification or documentation, replacement or return is arranged according to the sales contract. Claims should be submitted with photographs and the batch marking.
F304: Basic cost-effective grade for general ambient pipelines, water supply and compressed air systems.
F316: Molybdenum-alloyed grade with better chloride/acid corrosion resistance, ideal for chemical, seawater and pharmaceutical pipelines.
F321: Titanium-stabilized high-temperature grade that eliminates intergranular corrosion, built for steam lines, thermal power plants and heat transfer oil systems.
Yes. Each batch comes with an EN 10204 3.1 compliant MTR with unique melt number traceability. We perform 100% PMI testing before shipment, and third-party inspection reports are available on request.
