Abstract: Disclosed are a pre-tightening force repairing method, a repairing method involving a combination of a pre-tightening force and a clamp, and a repaired pipeline. The repairing method includes: (a) fixing part of a fiber material to a pipeline; (b) applying a pre-tightening force to the fiber material, winding multiple layers of the fiber material around the pipeline under the pre-tightening force; (c) in the state of applying the pre-tightening force, completing the curing of the multi-layer fiber composite material; and (d) mounting a clamp outside a repairing part of the fiber composite material. The magnitude of the pre-tightening force is designed to overcome the situation whereby a fiber composite material layer comes unstuck from the pipeline due to the radial shrinkage of the pipeline caused by a decrease in internal pressure and/or the axial stretching of the pipeline after the pipeline, which is under pressure, is repaired.

Abstract: A method for repairing/strengthening and crack arrest of pipe, especially metal pipe, in which, first, to cover an insulated material on the position needing repairing/strengthening and crack arrest, then to lay a high strength fiber composite material. The modulus of elasticity of the material used in the invention is close to the metal pipe's, it can be integrated with the pipe and bear the internal pressure with the pipe, thus the final composite pipe reaches required bear capacity, such as, the original most operation pressure of pipe can be recovered; and it can take effect for crack arrest of pipes when pipes happen burst accident. Otherwise, because of the insulated material is used on the bottom layer, it prevent thoroughly from galvanic corrosion between pipe and strengthening material.