Description
Product Detail
A weld neck flange is a butt-welded flange featuring a long tapered neck that transfers stress from the flange to the pipe, making it one of the most reliable flange types for high pressure, high temperature and cyclic service. It is widely used in process piping, offshore platforms, refineries, power plants and critical utility systems where strength, leak tightness and long service life are required.
SASA FLANGE supplies weld neck flanges in standard and customized dimensions according to ASME, EN, DIN, JIS, GB and project drawings. Each order can be supported with chemical analysis, mechanical testing, dimensional inspection, PMI testing, sealing face inspection, EN 10204 3.1 certificate and full heat number traceability to meet international project quality requirements.
- ✓Product Name: Weld Neck Flange
- ✓Material Grade: Carbon steel, stainless steel, alloy steel, low temperature steel and duplex stainless steel grades
- ✓Product Type: Forged pipe flange with long tapered hub and butt weld end
- ✓Main Feature: High strength connection, excellent stress distribution, reliable sealing for severe service
- ✓Applications: Oil and gas, petrochemical, power generation, shipbuilding, desalination and water treatment piping
Product Parameters
| Product Name | Weld Neck Flange |
| Material Grade | ASTM A105, A350 LF2, A694 F52/F60/F65, ASTM A182 F304/F304L/F316/F316L/F321/F11/F22/F91/F51/F53/F55 |
| Material Type | Carbon Steel, Stainless Steel, Alloy Steel, Low Temperature Steel, Duplex Stainless Steel, Super Duplex Stainless Steel |
| Product Form | Forged flange, machined flange, long weld neck flange, standard weld neck flange |
| Size Range | DN15 – DN1500 (1/2 inch – 60 inch) |
| Pressure Class | Class 150 – 2500 / PN6 – PN100 / JIS 5K – 40K |
| Sealing Face | RF, FF, RTJ, TG, MFM |
| Surface Treatment | Anti-rust oil, painted, hot-dip galvanized, pickling, passivation, machined finish |
| Standard | ASME B16.5, ASME B16.47 Series A/B, EN 1092-1, DIN, JIS B2220, GB/T 9119 or customer specification |
| Inspection | Chemical Analysis, Mechanical Test, PMI Test, Dimensional, Hydrostatic |
| Certificate | EN 10204 3.1 Material Certificate available |
| Processing Service | Cutting, CNC Machining, Custom Drilling, Custom Size Processing |
Chemical Composition
The following chemical composition is for reference based on a common carbon steel weld neck flange grade. Actual composition depends on the specified material grade, standard and heat number. Final chemical values shall comply with the applicable ASTM, EN, DIN, JIS or GB material standard and be confirmed by the mill test certificate.
| Element | C | Si | Mn | P | S | Cr | Ni | Mo | Other |
|---|---|---|---|---|---|---|---|---|---|
| ASTM A105 Content % | 0.35 max | 0.10 – 0.35 | 0.60 – 1.05 | 0.035 max | 0.040 max | 0.30 max | 0.40 max | 0.12 max | Cu 0.40 max |
Mechanical Properties
Mechanical properties of weld neck flanges vary according to material grade, heat treatment condition and section thickness. The data below shows typical minimum values for commonly requested grades used in industrial piping. For project orders, SASA FLANGE provides mechanical test reports in accordance with the relevant material standard and purchase specification.
| Grade | Tensile Strength | Yield Strength | Elongation | Hardness | Density |
|---|---|---|---|---|---|
| ASTM A105 | 485 MPa min | 250 MPa min | 22% min | 187 HB max | 7.85 g/cm3 |
| ASTM A182 F316/F316L | 515 MPa min | 205 MPa min | 30% min | 217 HB max | 7.98 g/cm3 |
Common Size Table
| Size Range | Pressure Class | Sealing Face | Material | Availability |
|---|---|---|---|---|
| DN15 – DN50 | Class 150 – 600 | RF | A105, F304L, F316L | Stock / Production |
| DN65 – DN300 | Class 150 – 1500 | RF / RTJ | A105, LF2, F304, F316, F11 | Stock / Production |
| DN350 – DN600 | Class 150 – 2500 | RF / RTJ | A105, A694 F52, F22, F316L | Production |
| DN700 – DN1500 | Class 150 – 900 | RF | A105, A350 LF2, F304L, F51 | Made to Order |
Different Specifications Comparison
| Type | Description | Typical Use |
|---|---|---|
| Raised Face Weld Neck Flange | Standard weld neck flange with raised sealing face for common gasket seating | General process piping, oil and gas, water and utility systems |
| Ring Type Joint Weld Neck Flange | High pressure weld neck flange with RTJ groove for metal ring gasket sealing | High pressure hydrocarbon, refinery and offshore systems |
| Long Weld Neck Flange | Extended hub design often used as a nozzle flange or vessel connection | Pressure vessels, columns, tanks and specialized piping connections |
| Flat Face Weld Neck Flange | Flat sealing face for use with full-face gaskets and cast iron equipment | Low pressure water service and equipment connections |
Equivalent Standards and International Names
Weld neck flanges are manufactured to multiple international dimensional standards, while material grades are selected separately according to ASTM, EN or other specified codes. Buyers should confirm both the flange standard and the forging material grade when ordering. The table below shows common dimensional standards and typical material equivalents used in global projects.
| Standard / Region | Standard Code | Typical Grade / Equivalent |
|---|---|---|
| USA | ASME B16.5 | ASTM A105, A182 F304/F316, A350 LF2, A694 F52 |
| Europe | EN 1092-1 | P245GH, C22.8, 1.4301, 1.4404, 1.4462 |
| Germany | DIN 2633 / 2635 / 2638 | C22.8, P250GH, 1.4571, 1.4462 |
| Japan | JIS B2220 | SFVC2A, SUS304, SUS316, SF440A |
| China | GB/T 9119 | 20#, 16Mn, 304, 316L, 2205 |
Production Process Flow
Weld neck flange quality depends on strict control of forging, heat treatment and precision machining. SASA FLANGE follows documented manufacturing procedures to ensure dimensional accuracy, sealing performance, traceability and compliance with project specifications.
- 1. Raw Material Selection
- 2. Forging / Cutting
- 3. Heat Treatment
- 4. Rough Machining
- 5. Finish Machining
- 6. Drilling
- 7. Surface Treatment
- 8. Inspection
- 9. Marking
- 10. Packing
- 11. Delivery
| Process Step | Description | Quality Control Point |
|---|---|---|
| Raw Material | Select certified forging billets or plates | Material certificate and traceability |
| Forging | Hot forging to achieve required shape | Forging temperature and reduction ratio |
| Heat Treatment | Normalizing, tempering or annealing | Temperature and holding time control |
| Machining | Sealing face, bolt holes, dimensions | Dimensional accuracy and surface finish |
| Inspection | Final inspection before shipment | Dimension, surface, PMI, hydrostatic |
Product Inspection
1. Chemical Composition Inspection
Chemical composition inspection is performed on raw material and finished flange samples to verify compliance with the specified grade such as A105, F316L or F11. Testing is carried out by spectrometer or laboratory analysis to confirm carbon, manganese, chromium, nickel, molybdenum and other required elements before release for production or shipment.
2. Mechanical Properties Testing
Mechanical testing verifies that the flange material meets the required tensile strength, yield strength, elongation and hardness values after forging and heat treatment. Test coupons are prepared according to applicable standards, and the results are reviewed against ASTM or EN requirements to ensure the weld neck flange performs safely in pressure piping service.
3. Dimensional Inspection
Dimensional inspection covers outer diameter, flange thickness, hub dimensions, bore size, bolt circle, bolt hole diameter, facing height and overall machining tolerances. Sealing face finish and concentricity are also checked to ensure proper gasket seating and alignment with mating flanges, reducing the risk of installation problems and leakage in the field.
4. PMI Testing and Hydrostatic Testing
PMI testing is available to confirm alloy identity for stainless steel, duplex and alloy steel weld neck flanges, preventing material mix-up on critical projects. Hydrostatic testing can be arranged according to customer specification or assembled system requirements. EN 10204 3.1 certificate, inspection records and heat number traceability are supplied for complete quality documentation.
Product Packaging
- ✓Wooden Case Packaging: Suitable for high-pressure and large-diameter products
- ✓Pallet Packing with Shrink Wrap: Suitable for batch shipments and standard sizes
- ✓Anti-rust Oil Coating + Waterproof Paper: Used for ocean freight protection
- ✓Individual Plastic Bag + Carton: Used for small fittings and threaded products
- ✓Clear Marking: Grade, size, pressure class, heat number and PO number
Applications
Weld neck flanges are preferred in piping systems that require high mechanical strength, reliable leak tightness and resistance to pressure or temperature cycling. Their tapered hub design reduces stress concentration and makes them suitable for critical service across many industrial sectors.
| Industry | Typical Applications | Why This Product Is Used |
|---|---|---|
| Oil and Gas | Transmission pipelines, refineries, gas processing units, offshore platforms | Provides strong butt-welded connection for high pressure, vibration and cyclic loading |
| Chemical Processing | Corrosive fluid lines, reactors, process skids, acid and solvent piping | Available in stainless and alloy grades for corrosion resistance and sealing reliability |
| Power Generation | Steam lines, boiler feed systems, turbine auxiliaries, high temperature piping | Handles elevated temperature and pressure with good stress distribution |
| Water Treatment | Pump stations, desalination units, filter systems, large utility pipelines | Offers durable flanged connection with easy maintenance and dependable gasket sealing |
| Marine and Offshore | Seawater systems, ballast lines, fire-fighting pipelines, topside process piping | Suitable for harsh service where strength, corrosion resistance and inspection traceability are important |
Why Choose SASA FLANGE?
- ✓Professional manufacturer of Weld Neck Flange for global industrial projects
- ✓Customized size, pressure class and material grade according to drawings
- ✓Full standard support: ASME, EN, DIN, JIS, GB, GOST and customer specifications
- ✓Material traceability with heat number control and EN 10204 3.1 material certificate
- ✓Chemical analysis, mechanical testing, PMI testing, hydrostatic and dimensional inspection
- ✓Stock availability for standard items, lead time 3-7 days; custom production 15-30 days
- ✓Export-grade packaging for sea, air and land transportation
- ✓15+ years experience supplying 50+ countries worldwide
FAQ
Q: What is a weld neck flange?
A: A weld neck flange is a forged flange with a long tapered hub that is butt welded to the pipe. This design improves stress distribution from the flange into the pipe wall and makes it suitable for high pressure, high temperature and severe cyclic service. It is widely used where joint integrity and long-term reliability are critical.
Q: What materials are available for weld neck flanges?
A: SASA FLANGE supplies weld neck flanges in carbon steel, low temperature carbon steel, stainless steel, alloy steel, duplex and super duplex grades. Common materials include ASTM A105, A350 LF2, A694 F52, A182 F304/F316, F11, F22, F91, F51 and F53, selected according to pressure, temperature and corrosion requirements.
Q: What pressure class is supported?
A: Weld neck flanges are available in ASME Class 150, 300, 400, 600, 900, 1500 and 2500, as well as EN PN6 to PN100 and JIS 5K to 40K ranges depending on size and standard. The correct pressure rating should be selected together with material grade and design temperature for the actual service condition.
Q: Can SASA FLANGE supply custom sizes?
A: Yes. SASA FLANGE can produce weld neck flanges to customized bore sizes, hub dimensions, drilling patterns, facing types and non-standard thicknesses based on drawings or project specifications. We also support special materials, long weld neck designs, RTJ grooves, large diameters and machining requirements for OEM and EPC project supply.
Q: What certificate is provided?
A: Standard documentation includes EN 10204 3.1 material certificate with heat number traceability. According to project requirements, SASA FLANGE can also provide MTC, dimensional inspection reports, PMI reports, mechanical test results, chemical analysis records and hydrostatic or other third-party inspection documents to support quality approval and export compliance.
Contact Us
If you are looking for weld neck flange or related custom flange products, please contact SASA FLANGE with your required size, pressure class, material grade, standard, surface treatment, quantity and inspection requirements. Our team will provide professional technical solutions and competitive quotation within 24 hours.
- 📧 Email: sales@sasaflange.com
- 📱 WhatsApp: +86 13764965049
- ☎️ Tel: +86 21 52236361
- 🌐 Website: www.sasaflange.com
