Flange Connection Types: WN, SO, BL, SW, TH, And LWN Explained

🔧 Flange Connection Types Explained

1. WN – Weld Neck Flange

Full Name: Weld Neck Flange

Connection: Butt-welded to the pipe

Features: Long tapered hub, strong weld joint

Advantages: Excellent strength and leak resistance under high pressure and temperature

Applications: Oil & gas, power plants, high-temperature pipelines

2. SO – Slip-On Flange

Full Name: Slip-On Flange

Connection: Pipe slips inside the bore; fillet weld on both sides

Features: Easy to align and install

Advantages: Low cost, simple installation

Applications: Low- to moderate-pressure systems in water, HVAC, fire protection

3. BL – Blind Flange

Full Name: Blind Flange

Connection: Bolted to pipe ends without bore

Features: Solid plate to block flow

Advantages: Ideal for sealing pipe ends and pressure testing

Applications: Pressure vessel ends, system isolation

4. SW – Socket Weld Flange

Full Name: Socket Weld Flange

Connection: Pipe inserted into socket; fillet welded on the outside

Features: Smooth bore alignment with pipe

Advantages: Good strength, better for small bore pipes

Applications: High-pressure, small-size pipelines

5. TH – Threaded Flange

Full Name: Threaded Flange

Connection: Screwed onto threaded pipe

Features: No welding required

Advantages: Easy installation, useful in explosive areas where welding is risky

Applications: Low-pressure systems, temporary setups

6. LWN – Long Weld Neck Flange

Full Name: Long Weld Neck Flange

Connection: Welded to equipment or vessel with long tapered neck

Features: Extra neck length distributes stress

Advantages: Ideal for high-stress environments and vessels

Applications: Pressure vessels, heat exchangers, reactors

✅ Quick Comparison Table