Built-in "Flange" (Washer Face)

Its most distinctive feature is a wide, flat, washer-like flange (collar) that is integrally formed with the bolt near the bolt head. This built-in flange structure eliminates the need for an additional washer, saving installation time while ensuring even pressure distribution across the flange surface-a factor critical for preventing leaks.

Bolt Head Design

Common head types include:

Hex head: The most widely used type, which can be easily tightened with a wrench.

Socket head: Suitable for narrow spaces where standard wrenches cannot reach (requires an Allen key for operation).

Square head: Less commonly used today, but still applied in some industrial scenarios due to its stronger grip.

Thread Type

Most flange bolts are partially threaded (only the end of the bolt shank is threaded). This design ensures that the unthreaded part of the shank bears the load (rather than the threaded part), which not only improves strength but also reduces wear on the flange bolt holes.

Thread standards vary by region (for example, the United States adopts the UNC/UNF thread standard, while Europe and Asia mostly use metric threads) to match the specifications of different flange bolt holes.

Material and Coating

The material selection of flange bolts depends on the environment of the system (such as pressure, temperature, and chemical exposure):

Carbon steel: Suitable for general low-pressure, non-corrosive scenarios.

Stainless steel (Grade 304, 316): Suitable for corrosive environments (e.g., chemical plants, marine systems).

Alloy steel (e.g., Grade A193 B7): Suitable for high-pressure, high-temperature systems (e.g., oil refineries, power plants).