Slip on Flange midaspipelines.com

Slip on flanges, also called SO flanges, are a popular type of pipe flange designed to accept pipe into the bore/center of the flange for welding around both the Outer Diameter (OD) of the pipe and on the interior side of the connection.

The slip-on flange is a straightforward alternative to a weld neck flange, offering flexibility in adjusting the pipe length relative to the flange’s position due to its lack of a weld bevel. This design provides ample clearance for the pipe and facilitates easier welding and fabrication.

Primarily used in lower pressure applications, slip-on flanges typically feature a hub that resembles a raised face but can also be supplied in a "ring style" without a hub if space constraints demand it. While the hub style is more prevalent, the ring style is also valid within the slip-on category. For higher pressure applications, slip-on flanges may be manufactured with a lap joint height for improved connection quality. In cases where a lap joint is unavailable or the hub height is not critical, a slip-on flange can be produced with a machined hub to resemble a lap joint style.

In general, slip-on flanges are less suitable for high-stress applications compared to weld neck flanges. The latter features a reinforced hub and a tapered weld bevel, providing a more robust connection to the pipe’s butt weld end, which is better suited for environments subject to significant mechanical stress.