A split flange is a type of flange that can be easily installed on pre-existing piping. It is made up of two interlocking pieces that fit securely together using nuts and bolts or welding it into place. Because it is made of two parts, split flanges are used to reinforce weakened areas of piping, or to add an attachment in places conventional flanges cannot.

Split-flange fittings use rubber O-rings to seal joints and contain pressurized fluid. The O-ring sits in a groove on the flange, and then mates with a port's flat surface. The flange is then attached to the port with four mounting bolts. The bolts tighten downward onto the clamps of the flange, thereby eliminating the need for large wrenches to connect the components of large-diameter tubing.