When purchasing valves, random documents provided by the supplier are required.

This needs to be divided into various situations. If it is only used for valves on ordinary pipelines, only pressure test records and simple material certificates of pressure-bearing parts are required. If it is used in very important places (such as nuclear power plants, submarines, and high-temperature and high-pressure boilers), the supplier will need to provide very complete random documents, such as raw material chemical composition analysis, mechanical properties, heat treatment reports, and parts of important parts. Processing records, detailed records of valve pressure tests, and even valve painting and packaging, etc. Of course the price is also very different.

Hope it helps.