Abstract: An in situ apparatus, system, and method for cladding or repairing cladding in installed pipelines are presented. The apparatus can include a coating collar, a material reservoir, a cladding head, an adjustable cladding chamber, and a chamber controller. The coating collar can include an external surface, a first circumferential wall, and a second circumferential wall and forms the adjustable cladding chamber along with interior wall of the pipe. The coating collar can have an aperture to include and allow deployment of the cladding head through it. The cladding head can be operatively coupled with the cladding material reservoir to allow efficient deployment of the cladding material on the pipe surface. The chamber controller can be coupled with the adjustable cladding chamber to control dimensions of the chamber thus restricting and controlling the environment and enabling efficient functioning of the cladding head and limiting grain growth in applied nanoclad materials.