In the production of head products, users need to provide the corresponding size rules, in order to meet the custom requirements. This includes many aspects, the nominal diameter of the head is one of them, this parameter is composed of many aspects, we might as well to understand.

The nominal diameter of the head is also called the average of the outer diameter, which mainly includes the nominal diameter of the pressure vessel, the nominal diameter of the components of the vessel and the nominal diameter of the pipes connecting the components. Pressure vessels are generally tubular structure, so its nominal diameter mainly refers to the inner diameter of the cylinder, only in the container made of seamless steel tube will also take the outer diameter as the nominal diameter. When designing the head size, the nominal diameter should be consistent with the cylinder with easy pressure.

In addition to the cylinder, there are many other components on the pressure vessel, their nominal diameter should match the head head. Pipes are usually used as connecting parts, and their nominal diameters must meet the requirements of installation standards in order to ensure that they meet the requirements of airtightness.