ASTM A193 Grade B7 Duble End Studs

A Double End Stud, also known as a double head Stud, is a cylindrical fastener with threads at both ends. It finds widespread application across various industries including power, chemical, oil refining, valves, railways, bridges, steel structures, automotive parts, machinery, boiler steel structures, suspension towers, large-span steel structures, and large buildings.

The diameter, length, and quantity of double head studs must meet specific requirements, and their type and material are determined by their grade. Commonly used double head studs, also referred to as full thread studs, come in two types: coarse and fine threads. Coarse threads are denoted by M followed by the nominal diameter, while fine threads are represented by M followed by the nominal diameter and pitch.

According to fastener standards, M36 bolts typically utilize coarse threads, while M36 and larger diameters can use fine threads with a pitch of 3.

The usage of double head studs varies depending on their dimensions:

• Double head studs with a bm=1d ratio are generally employed for connecting two steel parts.
• Those with bm=1.25d and bm=1.5d ratios are commonly used for connecting cast iron and steel connectors.
• Double head studs with bm=2d are typically used for connecting aluminum alloy connectors and steel connectors.

The former type of connector mentioned above features internal threaded holes, while the latter type has through holes. Double head studs with equal length threads on both ends require nuts and washers to connect two parts with through holes. One end of a welding stud is welded to the surface of a connected part, while the other end (threaded end) passes through the connected part with a through hole. Subsequently, a washer is installed, and a nut is screwed on to connect the two parts as a whole.

Popular types of double head studs include B7 Double Head Studs, SA193-B7 Double Head Studs, and High Strength Double Head Studs, such as the American SA193-B7 double head studs.