Direct factory supply from Shanxi Yuxin Casting & Forging Co., Ltd. Engineered to ASME, EN, DIN, and custom technical drawing specifications.
In high-pressure piping infrastructure, petrochemical processing plants, and severe-service offshore installations, the Weld Neck Flange (WNF) serves as the gold standard for leak-tight structural connection. Unlike flat-face slip-on or lap-joint configurations, a weld neck flange features a long, tapered hub that transitions smooth mechanical stress directly into the connected pipe wall. Translating raw process specifications into a reliable, code-compliant physical forging requires an authoritative understanding of a Weld Neck Flange Drawing.
A technical 2D CAD blueprint or 3D STEP file for a weld neck flange is far more than a simple dimensional schematic. It defines critical geometric parameters engineered to withstand internal hydrostatic pressure, external bending moments, thermal expansion cycles, and volatile fluid dynamics. Precision manufacturing in China’s premier forging hubs—most notably Dingxiang County in Shanxi Province—hinges upon absolute fidelity to these technical drawings, adherence to international standards (ASME B16.5, ASME B16.47, EN 1092-1 Type 11, DIN 2633), and full metallurgical control from raw billet to final machining.
The long tapered hub of a weld neck flange provides a gradual transition of material thickness, reducing the stress concentration factor ($K_t$) at the root of the flange ring. This geometry prevents localized plastic deformation under severe thermal shock and high-frequency line vibrations.
When evaluating a manufacturer's CAD drawing, piping engineers and procurement teams must inspect seven fundamental dimensional coordinates:
Cross-reference dimensional variables for engineering approval and CAD drafting accuracy.
| Standard & Type | Pressure Class / PN | Size Envelope | Facing Variations | Standard Bevel Angle | Machining Serration (Ra) |
|---|---|---|---|---|---|
| ASME B16.5 WNF | Class 150 – 2500 | NPS ½" to 24" | RF, FF, RTJ, Male/Female | 37.5° ± 2.5° (ASME B16.25) | 3.2 – 6.3 µm (125 – 250 µin) |
| ASME B16.47 Ser. A | Class 75 – 900 | NPS 26" to 60" | RF, RTJ | 37.5° ± 2.5° (Thick walls compound) | 3.2 – 6.3 µm (Stock Finish) |
| ASME B16.47 Ser. B | Class 75 – 900 | NPS 26" to 60" | RF, RTJ (Compact Bolt Circle) | 37.5° ± 2.5° | 3.2 – 6.3 µm (125 – 250 µin) |
| EN 1092-1 Type 11 | PN 6 – PN 400 | DN 10 to DN 4000 | Type A (Flat), B1/B2 (RF), C/D/E/F | 30° (+5°/-0°) per EN ISO 9692-1 | 3.2 – 12.5 µm (depending on PN) |
| DIN 2631 - 2638 | PN 6 – PN 160 | DN 10 to DN 2000 | Form C, D, E, F, N, V | 30° per DIN 2559 | Form C: Ra 3.2 µm / Smooth |
Established in 1992 in the Zhuangli Enclave Industrial Zone of Dingxiang County, Shanxi Province—widely recognized as the “Hometown of Forging in China”—Shanxi Yuxin Casting & Forging Co., Ltd. operates as a true direct forge mill rather than an export trading desk. Occupying a modern industrial footprint with an annual forging output of over 10,000 metric tons of flanges and 2,000 tons of specialized ring forgings, YUXIN delivers end-to-end metallurgical control from raw ingot breakdown to 5-axis CNC precision machining.
Every custom Weld Neck Flange drawing submitted to YUXIN undergoes rigorous computer-aided finite element analysis (FEA) and forging flow simulation. Forgings are certified under ISO 9001:2015, PED 2014/68/EU (TÜV Rheinland), AD 2000-Merkblatt W0, and VdTÜV 350 / 399-3, accompanied by fully traceable EN 10204 3.1 or third-party witnessed 3.2 Material Test Reports (MTR).
The structural integrity of a weld neck flange relies heavily on material selection tailored to operating temperature, medium toxicity, pressure level, and environmental corrosion. Shanxi Yuxin manufactures flanges across four primary metallurgical families:
ASTM A105 / Q235B / C22.8 / P250GH: Standard forged carbon steel for ambient and high-temperature pressure systems. Normalized heat treatment guarantees fine grain structure and excellent notch toughness.
ASTM A350 LF2 (Class 1 & 2) / LF3: Engineered for sub-zero impact resilience down to -46°C (-50°F). Essential for Arctic oilfield pipelines, gas treatment headers, and refrigeration process units.
ASTM A182 F11, F22, F91: Chromium-Molybdenum alloy forgings offering high creep-rupture strength at elevated temperatures up to 650°C in refinery hydrocrackers and power plant boilers.
ASTM A182 F304/304L, F316/316L, Duplex 2205, Super Duplex 2507: Maximum resistance to pitting, crevice corrosion, and chloride stress-corrosion cracking in marine and offshore sour environments.
Custom engineered forgings solving critical piping challenges in severe operating environments across 40+ nations.
High-pressure Class 1500 and 2500 Ring Type Joint (RTJ) weld neck flanges machined from ASTM A182 F51 / F53. Designed according to API 6A and NACE MR0175 specifications to resist sour gas ($H_2S$) cracking in subsea oilfield extraction.
Large-diameter ASME B16.47 Series A weld neck flanges forged from ASTM A182 F22/F91. Engineered to handle continuous thermal cycling at 550°C with ultra-low thermal relaxation and tight gasket compression retention.
Custom drawings requiring ultra-clean stainless steel (F316L) or A350 LF2 Class 2 materials. Verified with Charpy V-notch impact testing at -196°C to guarantee structural ductility without brittle transition failures.
Zero-permeation, ultra-dense forged weld neck flanges for high-pressure hydrogen transport lines (up to 700 bar). Machined with smooth, high-precision facing finishes (Ra 0.8–1.6 µm) to ensure micro-gasket gas containment.
How Shanxi Yuxin integrates AI-driven drawing conversion, closed-die ring rolling, and CRA cladding technology.
The global pipe fitting industry is undergoing a digital and metallurgical transformation. As engineering projects demand faster lead times and higher safety margins, traditional manual drawing interpretation is giving way to automated digital engineering workflows:
Clear answers to procurement, engineering, and quality control inquiries.
When submitting a drawing for custom quotation or forging, you must provide: (1) Nominal Pipe Size (NPS/DN), (2) Pressure Class or PN rating, (3) Matching Pipe Bore or Schedule (e.g., Sch 40, Sch 80, XXS), (4) Outer Diameter of Flange (O), (5) Flange Thickness (C), (6) Length Through Hub (Y), (7) Facing Type (RF, FF, RTJ) and serration roughness finish (Ra), and (8) Material grade specification (e.g., ASTM A105, A182 F316L).
ASME B16.5 covers flange sizes from NPS ½" up to NPS 24". For pipeline sizes NPS 26" to NPS 60", ASME B16.47 applies. Within B16.47, Series A (MSS SP-44) features thicker flanges, larger bolt circles, and heavier weight, making it preferred for general piping and offshore applications. Series B (API 605) features a more compact bolt circle and smaller bolts, making it lighter and tailored for compact refinery and gas pipeline manifolds.
If the internal bore of the weld neck flange is smaller or larger than the mating pipe wall, it creates a physical step or ledge inside the flow path. This ledge causes localized fluid turbulence, increased pressure loss, cavitation, and accelerated erosion-corrosion. Machining the bore to match the pipe's schedule ensures a smooth, uniform hydraulic transition.
Every shipment from Shanxi Yuxin includes a comprehensive document package: EN 10204 3.1 Mill Test Certificate (MTC) detailing heat number, ladle chemical analysis, tensile/yield/elongation mechanical properties, heat treatment chart, hardness report, 100% Ultrasonic Testing (UT) / Magnetic Particle (MT) non-destructive examination report, and full dimensional measurement sheets.
Yes. Beyond standard ASME, EN, DIN, JIS, and GOST catalogues, YUXIN specializes in custom drawing-based forgings. Our in-house tool and die shop can forge custom hub rings, heavy-wall tube sheets, expansion joint flanges, and non-standard reducers up to 3,000 mm (120 inches) in diameter.
Explore our full line of blind, threaded, slip-on, and custom-machined industrial flanges.
Send us your 2D CAD files (DWG/PDF) or 3D STEP models. Our engineering team at Shanxi Yuxin Casting & Forging Co., Ltd. will review your tolerances, material specs, and heat treatment requirements within 24 hours.
