ASME B16.5 DN15-DN1200 Weld Neck Flanges Resistant to Extreme Temperature

1. Product Description
The weld neck flange is a pipe flange featuring a tapered neck that transitions smoothly from the flange face to the pipe wall. The neck provides reinforcement and reduces stress concentration at the connection point, making it suitable for high-pressure and high-temperature pipeline systems. It is connected to the pipe by butt welding, ensuring a strong, leak-resistant joint. Available in raised face (RF), flat face (FF), and ring type joint (RTJ) sealing faces.

2. Key Specifications

• Material: Carbon Steel (A105), Stainless Steel (304/316/321), Alloy Steel (F11/F22), Duplex Steel

• Nominal Size: 1/2” – 60” (DN15 – DN1500)

• Pressure Rating: Class 150, 300, 600, 900, 1500, 2500

• Flange Face Type: Raised Face (RF) / Flat Face (FF) / Ring Type Joint (RTJ)

• Wall Thickness / Schedule: SCH10 – SCH160, STD, XS, XXS

• Connection: Butt Weld

• Standards: ASME B16.5, ASME B16.47, DIN, EN1092, JIS, GB/T9115

• Surface Treatment: Anti-rust oil, galvanized, or passivated

3. Applications
Widely used in petroleum, chemical, natural gas, power generation, nuclear energy, shipbuilding, papermaking, food processing, water treatment, and municipal construction. Particularly suitable for high-pressure, high-temperature, and critical pipeline systems requiring reliable sealing and structural integrity.

4. Product Advantages

• Tapered neck design distributes stress evenly, reducing fatigue at the weld joint

• Strong butt-weld connection provides excellent joint integrity under high pressure and temperature

• Smooth bore minimizes turbulence and flow resistance

• Available in a wide range of pressure classes and materials

• Easy to inspect and test after welding

• Compatible with standard gaskets and bolting for simplified assembly

5. Product Functions
The weld neck flange connects pipes, valves, pumps, and other equipment to form a sealed pipeline system. Its butt-welded neck ensures a continuous, strong joint capable of withstanding high pressure, temperature fluctuations, and cyclic loading. It also allows easy disassembly and maintenance at flanged connections.

6. Instruction for Use

• Verify flange size, pressure class, and face type match the pipeline and mating flange.

• Clean the pipe end and flange neck; remove oil, rust, and debris.

• Align the flange with the pipe, ensuring the flange face is perpendicular to the pipe axis.

• Tack-weld at several points, then complete butt welding per applicable standard (e.g., ASME B31.3).

• Allow the weld to cool; inspect for defects.

• Install the gasket, align with the mating flange, and tighten bolts in a cross pattern to the specified torque.

• Perform a pressure test to confirm no leakage.

7. Precautions

• Do not subject the flange to impact or drop during storage and handling.

• Keep stainless steel flanges away from contact with dissimilar metals to prevent galvanic corrosion.

• Ensure the pipeline is depressurized and drained before installation or maintenance.

• Do not use damaged or deformed flanges; inspect the neck and face for cracks before welding.

• Use the correct gasket material compatible with the fluid and operating temperature.

• Tighten bolts evenly and in a cross pattern to avoid uneven gasket compression.

• For high-pressure applications, use flanges with verified material certificates.

8. Shipping Information

• Standard export packing: wooden case or pallet with moisture-proof wrapping.

• Dispatch within 3–7 working days for stock items; 15–30 days for customized or bulk orders.

• Shipping methods: sea freight, air freight, or express courier (DHL/FedEx/UPS) depending on quantity and destination.

• Tracking number provided upon dispatch.

9. Payment Terms

• T/T (bank transfer): 30% deposit, 70% balance before shipment.

• L/C at sight accepted for orders exceeding USD 10,000.

• PayPal / Western Union for sample orders.

• All prices are quoted EXW or FOB unless otherwise specified.

10. Packaging

• Each flange is wrapped in plastic film or bubble bag.

• Multiple pieces are packed in sturdy wooden cases or pallets.

• Desiccant is added for sea shipments to prevent moisture.

• Custom labeling and marking available upon request.

• Flange faces are protected with covers to prevent damage during transport.

11. Return & After-Sales Policy

• 7-day return or exchange for quality defects (buyer bears return freight unless the defect is verified as our responsibility).

• Custom-made or non-stock items are not eligible for return unless defective.

• Warranty period: 12 months from delivery for manufacturing defects.

• Claims for shortage or damage must be reported within 3 working days of receipt with photo evidence.

• Technical support available for installation, gasket selection, and bolting torque