Common flanges, due to their use in various locations, exhibit differences in pressure ratings to some extent. For instance, large stainless steel flanges are primarily used in chemical engineering for high-temperature pipelines, thus demanding high material pressure-bearing performance.

Customers often request forged flanges, as the material's density is increased through forging, thereby enhancing its pressure-bearing capacity.

Large stainless steel flanges are subject to clear pressure ratings in both domestic and international standards, typically categorized as PN25, PN6, PN10, PN16, PN25, PN40, and so on. The most commonly used are PN10 and PN16. A flange, also known as a flange hub or boss, is a component that connects shafts to each other, used for pipe end connections; there are also flanges used at equipment inlets and outlets for connecting two pieces of equipment, such as reducer flanges.

Flanged connections, or flange joints, refer to a removable connection that consists of a flange, a gasket, and bolts, all three interconnected to form a combined sealing assembly.

The pressure class of a flange is related to its design pressure, but they are not the same. It represents a flange's strength series. The higher the pressure class, the stronger the flange.

To be precise, given the material, design temperature, and design pressure, we can select a pressure grade for a category of piping within a process unit based on the temperature-pressure curves on the flange standards, and from there determine the pressure grades for valves and other piping components.

Pressure ratings can vary depending on the flange standard system, such as the European system, the American system, etc., like PN1.6, PN2.5, or CL150/PN2.0, etc. Of course, some standards combine the two. Since flanges are used in different locations, there are certain distinctions in pressure ratings, for instance, large stainless steel flanges are primarily used in chemical engineering for high-temperature pipelines, thus demanding high pressure-bearing properties from their materials.

Therefore, customers often demand forged flanges, as the material's tissue density is enhanced through forging.