Inserts come in one of 3 types, and are called so because of their design that enables pipes to ‘insert’ themselves into one side, while the other is welded on to another size pipe – usually one of a smaller size – thus acting as a reducing fitting. The ‘insert’ side of these Fittings come in either a threaded or socket weld design, depending on applicability.
The type 1 insert has a slight bevel from the ‘insert’ part as it reduces through the fitting. This enables larger sizes to be reduced without an excessively weighted fitting.
The type 2 insert is a cylindrical piece, and the easiest to fabricate. This type of insert is the most common design.
The type 3 insert has a reversed bevel, and a slight lip that increases the outside diameter of the piece from the ‘insert’ portion through the fitting. This allows the fitting to safely sustain sufficient pressure while enabling a one step reduction.