Pressure vessels lose their normal working capacity due to excessive mechanical or temperature loads and are called failures. There are three forms:

1. Strength failure: excessive plastic deformation or cracking of the container under load.

2. Stiffness failure: excessive elastic deformation of the container, resulting in difficulty in transportation, installation or loss of normal working ability.

3. Stable failure: The sudden change in shape of the container under load results in loss of working ability.

The design of the pressure vessel must take into account the above three failure possibilities and should be fully considered to ensure the normal use of the equipment.

Detailed description of the pressure vessel

(1) The maximum working pressure (Pw) (Note 1) is greater than or equal to 0.1Mpa (without hydrostatic pressure, the same below);

(2) The inner diameter (non-shaped section refers to its largest dimension) is greater than or equal to 0.15 m, and the volume (V) (Note 2) is greater than or equal to 0.25 m3;

(3) The containing medium is a gas liquefied gas or a liquid with a maximum working temperature higher than or equal to the standard boiling point.

Pressure vessels are used in a wide variety of applications. It is an equipment that plays an important role in various sectors of the national economy, such as the petrochemical industry, the energy industry, scientific research, and military industry. The pressure vessel generally consists of a cylinder body, a head, a flange, a sealing element, an opening and a nozzle, and a support. In addition, it is equipped with safety devices, gauges and internals that perform different production processes. Pressure vessels are prone to explosions, fires and fires that endanger the safety of people, equipment and property and environmental pollution due to sealing, pressure and media. At present, all countries in the world regard it as an important inspection and inspection product. The specialized agencies designated by the state implement supervision and inspection and technical inspection in accordance with the regulations and standards stipulated by the state.