Thick-walled cylinder \"self-reinforcement”

Principle: Self-reinforcement involves subjecting thick-walled cylinders to a pressure higher than the operating pressure before use, thereby creating prestress that helps to make the stress within the wall uniform during operation. Function: Forms a plastic layer and an elastic layer under overpressure. After pressure is released, the plastic layer retains residual strain; the elastic layer, hindered by this residual strain, also fails to return to its original position, resulting in an interaction force between the two layers. Residual compressive stress is formed in the plastic layer, residual tensile stress is formed in the elastic layer, and prestress is generated in the cylinder wall. Methods: 1. Hydraulic method: An ultra-high-pressure hydraulic pump is used to apply pressure to a sealed thick-walled cylinder, causing plastic deformation of its inner wall. 2. Mechanical extrusion method: Plastic deformation of the inner layer of the cylinder wall is achieved by using a punch or a hydraulic press to force the shaft with an interference fit into the thick-walled cylinder, or by using a bridge crane to pull the shaft across the thick-walled cylinder. 3. Explosive expansion pressure method: High-energy sources are used to generate high pressure and shock waves in an extremely short time, thereby causing plastic deformation of the cylinder.

See Chapter 5 of Wang Zhiwen’s “Design of Chemical Engineering Vessels”.