The Flat Welding Flange with Neck, commonly known as a Slip-On Flange (SO Flange), is designed to slide over the pipe and be fillet welded on both the inside and outside.
It features a short hub (neck) that provides improved alignment and moderate strength, making it suitable for low to medium pressure piping systems.
This type of flange offers a good balance between ease of installation, cost efficiency, and performance.