Some metallic pipelines suffer from corrosion issues due to internal and external environmental conditions. The pipe-in-pipe technology has been developed by inserting a new pipe (e.g., plastic pipe or flexible pipe) into an existing pipeline. The pipe-in-pipe approach may be applicable to the reconstruction of an existing pipeline, where the existing pipe is used as protective casing and the inserted new pipe is used to contain corrosive petrochemicals. The new pipe is installed in the long existing pipeline with several bends. The magnitude of the pull-in load and the response of the inserted pipe are the major concerns during installation. This paper presents the installation process of inserting a plastic pipe into an existing steel pipe, based on model tests, finite element analysis (FEA), and analytical investigations. First, a series of model tests are presented. In order to optimize the process of installation, sensitivity analyses based on model tests were conducted to study the influence of some key parameters, including the radius of curvature of the pipeline and diameter of the pipe. Then ABAQUS finite element models were applied to analyze the major factors. In addition, analytical studies on calculating the pull-in load are presented to make a comparison with the FEA and model test results. Since little previous work has been done about simulating the installation process of this kind of rehabilitation, the proposed finite element analysis results and the analytical studies of the installation can serve as a feasibility study for the design and evaluation of offshore pipeline rehabilitation project.