Today the number, shapes and sizes of different types of nuts, bolts and fasteners has grown almost to a point where if you aren’t immersed in it every day it is hard to keep up with the many different types and the applications in which they are best suited for. This short article points out different types of bolts and the main applications they are used for today.

Square head bolts are a type of bolt that have a square shaped external wrenching head, thus giving the name square head bolt. These are typically made from carbon steel and because of the square shaped head they provide a large bearing area for positive gripping. The square head makes them easy to tighten in blind areas perfect for tight areas. While head bolts are used in many applications they are used largely in the new buildings for aesthetics and in the railroad industry.

Carriage bolts are another bolt that is widely popular mainly for use with bare timber as well as fastening metal components. Carriage bolts are round headed bolt with the portion directly beneath the head formed into a square section. When used on bare timber this makes the bolt self locking when places through a round hole or a square hole when used with metal components. Like all fasteners carriage bolts are used for many applications so they come in many different sizes to suit the need of the application.

U bolts not as commonly used as other bolts get their name from their shape, they are a bolt shaped in the form of the letter “U” with screw threads on either end. Primarily speaking u bolts are used to support pipework in buildings for pipes typically carrying carious gases and fluids. Because of their application U bolts are typically described by what type of pipe it will be used to support. This would be a description that would include the pipes thread length, thread size, inside height and diameter.

Lag Bolts are among the toughest types of bolts as they are generally used to connect heavy pieces of lumber and various other material that carry an intense load. Lag bolts also known as lag screws come in many sizes with diameters from ¼” to 1 ¼ ” and lengths up to 6″ or more. Lag bolts typically have an external hex head and require a nut to help support the heavy weight they are intended to support.

Square head bolts, carriage bolts, U bolts and lag bolts are types that we are commonly asked about and what they actually are. Hopefully this provides a good explanation to those looking to better understand the use, design, and intentions for each of these types of bolts.