A coupling assembly and method for retrofitting a water pipe for installation of a pipe insert or device is disclosed. The coupling assembly may include a plunger assembly, a two-part clam shell, an adapter port, and an internally ribbed flexible sleeve including first internal ribs and second internal ribs, wherein the first internal ribs are configured to engage a grooved portion of the adapter port. Prior to installation, a first portion of the internally ribbed flexible sleeve may be attached to the adapter port and a second portion of the sleeve may be rolled up over the first portion. The method may include aligning the port adapter with the cut water pipe; rolling the second portion of the sleeve from the port adapter onto the cut pipe; placing a two-piece clam shell over the sleeve; and tightening two oppositely treaded nuts over the two-piece clam shell.