Welding Neck Flanges  Manufacturers, Traders, Suppliers

Dimensions and wall thickness
Welding neck flanges (acc. ANSI B 16.5) are available in dimensions from ½“ upto 24“ and in a wall thickness of STD/XS/S160/XXS.
Special competence for special materials
Threaded flanges can be ordered for the following pressure stages (150/300/600/900/1500/2500 lbs). Our speciality is the delivery of special materials.
Technical data
More details, technical data and dimensions can be seen from our data sheet „flanges“ in the download area. Information on special measurements and special designs will be given upon your request.
WAZ (acceptance test certificate)
Of course, you may obtain a standard WAZ 3.1 with each delivery. Upon request, we are able to deliver a WAZ 3.2 (normally TÜV or other inspection institutions).

Here's a detailed overview of the production process for a Welding Neck Flange (WN Flange), which combines forging, machining, and quality control to ensure strength and precision:
Production Process of Welding Neck Flange
1. Raw Material Selection

• Material: Carbon steel, stainless steel, alloy steel, etc. (e.g., P250GH,A105, SS304, F11)
• Form: Usually round steel billets or ingots
• Quality Check: Chemical composition & mechanical properties verified before use

2. Forging

• Heating: Billets are heated in a furnace to approx. 1,100–1,250°C
• Open Die or Closed Die Forging: The heated billet is formed into the basic flange shape using high-pressure hammer or press
• Rough Shape Formed: Includes the flange face, neck, and hub

3. Heat Treatment

• Normalizing / Annealing / Quenching & Tempering (depending on material & standard)
• Improves mechanical strength, grain structure, and machinability

4. Rough Machining

• Turning of outer diameter (OD), inner bore, and thickness
• Drilling of the bolt circle holes and shaping of the hub
• Prepares the flange for accurate final machining

5. Final Machining (Finish Machining)

• Precision machining of:

• Raised face (RF), RTJ, or flat face
• Neck to match pipe schedule
• Bore to exact dimension
• Bolt holes drilled to specification

CNC machines are used to ensure tight tolerances

6. Inspection & Testing

• Dimensional Inspection
• Visual & Surface Defect Inspection
• Ultrasonic Testing (UT) or Radiographic Testing (RT) (especially for pressure-critical flanges)
• Hardness Testing, Hydrostatic Testing, Marking Check

7. Surface Treatment

• Anti-rust coating: Black paint, oiling, zinc plating, hot dipping galvanzied
• Surface Finish: According to ASME, EN, or DIN standards (typically Ra 3.2–6.3 µm for RF)

8. Marking & Packaging

• Marking: Standard, size, material, pressure class, heat number
• Packaging: Wooden pallets, crates, or custom packaging with anti-corrosion wrap

Applications of Welding Neck Flanges
Welding neck flanges (WN flanges) are widely used in industries that require high strength, durability, and reliable sealing under high pressure and temperature. Their long tapered hub and butt-welded connection provide excellent stress distribution and reduce the risk of failure.
Typical Applications:
1. Oil & Gas Industry

• Pipelines transporting crude oil, natural gas, or refined products
• Offshore drilling platforms and subsea systems
• Refineries and petrochemical plants

2. Petrochemical & Chemical Plants

• Chemical reactors, pressure vessels, and heat exchangers
• Systems requiring corrosion-resistant materials

3. Power Generation

• Steam pipelines in thermal power plants
• Nuclear and combined cycle power plants
• Boiler systems and condensate lines

4. Water Treatment & Desalination

• High-pressure piping for seawater intake and distribution
• Pumping stations and pressure control systems

5. Shipbuilding & Marine Engineering

• Piping systems in cargo ships and naval vessels
• LNG and LPG carrier piping

6. Aerospace & Defense

• High-performance piping systems in defense manufacturing
• Fuel and hydraulic systems requiring precision and reliability

7. Pharmaceutical & Food Industries

• Sterile piping where smooth internal bore and reliable sealing are crucial (when using stainless steel)