Weld Neck Flange

A steel flange is a pipe fitting used to connect pipes, valves, pumps, and other equipment in a piping system. It provides easy assembly, disassembly, and maintenance while ensuring a leak-proof seal under high pressure and temperature conditions.

1. Classification of Steel Flanges

A. By Connection Type

1. Weld Neck Flange (WN)

   • Features a long tapered hub for smooth stress distribution.

   • Used in high-pressure and high-temperature applications (oil & gas, petrochemical).

2. Slip-On Flange (SO)

   • Slides over the pipe and is welded on both sides.

   • Easier to align but less robust than weld neck flanges.

3. Socket Weld Flange (SW)

   • Pipe is inserted into the flange and welded for a strong joint.

   • Ideal for small-diameter, high-pressure piping.

4. Lap Joint Flange (LJ)

   • Used with a stub end, allowing easy rotation for alignment.

   • Common in systems requiring frequent dismantling.

5. Threaded Flange (TH)

   • Screws onto pipes without welding.

   • Used in low-pressure, non-critical applications.

6. Blind Flange (BL)

   • Seals the end of a piping system.

   • Used for pressure testing, isolation, or future expansion.

7. Orifice Flange

   • Designed for flow measurement (used with orifice plates).

B. By Facing Type

• Flat Face (FF) – For low-pressure applications.

• Raised Face (RF) – Most common, provides better sealing.

• Ring-Type Joint (RTJ) – Used in high-pressure, high-temperature systems.

• Tongue & Groove (T&G), Male & Female (M&F) – For precise alignment.

2. Materials Used in Steel Flanges

3. Applications of Steel Flanges

✔ Oil & Gas Industry – Pipeline connections, refineries.
✔ Chemical & Petrochemical Plants – Corrosive fluid handling.
✔ Water Treatment & HVAC – Pump and valve connections.
✔ Power Plants – High-pressure steam systems.
✔ Shipbuilding & Marine – Saltwater-resistant piping.
✔ Food & Pharmaceutical – Hygienic, easy-to-clean systems.