Two main approaches are included in this form of replacement application.
In the first approach, a new pipe of smaller outside diameter than the inside diameter of the existing pipe is inserted (pushed or pulled) within the existing pipe and provides a complete replacement of the structural and flow functions of the existing pipe. This is usually referred to as "slip lining" and is categorized here as replacement slip lining to separate it from slip lining designed to serve as a renovation. Slip lining methods are described in more detail in separate boxes.
In the second approach, many of the "renovation" methods may be considered to provide a pipe replacement provided their design allows the new liner to carry all the internal and external loads required without consideration of the existence of the host pipe (including any enhancement to the buckling resistance of the liner). When they are designed in this way, they are considered here to be a fully-independent rehabilitation and to function as a "replacement".