The definition of a pressure vessel

A pressure vessel is a closed container that can withstand internal pressure. It is usually used to store, transport, or process gases, liquids, and other substances.

Specifically, pressure vessels need to meet the following characteristics: 

1. Withstand pressure: The internal pressure may come from the substances stored or processed, or it may be due to external applied pressure. 

2. Airtightness: The container needs to maintain good sealing to prevent the leakage of substances. 

3. Safety: The design, manufacture, and use of pressure vessels all need to follow strict safety standards to ensure that there are no dangers such as cracking or explosion in normal operation and possible abnormal situations. 

Pressure vessels have a wide range of applications, such as gas storage tanks, gas cylinders, boilers, reaction kettles, etc. They play an important role in many industries such as chemical, petroleum, energy, and pharmaceuticals. 

When using pressure vessels, it is necessary to strictly comply with relevant safety regulations and operating procedures, and carry out regular inspections and maintenance to ensure their safe and reliable operation.