Flange bolts has a wide, circular base that is integrated into the bolt head. This wide, circular base is meant to distribute the clamping loads of the bolt over a larger area. Because the flange bolts spread the clamping load over a larger area, they are used to reduce stress on the material that are being clamped, espeshally soft materials like aluminum.
Some flange bolts has serrations on the underside of the flange. These serrations allow the bolt to grip the material it is being used on, and they prevent the bolt from loosening from vibration. The markings on the head of the bolt represent the strength of a flange bolt.
Flange Bolts: Uses, Grades and How to Tighten
Three radial lines on a flange bolt indicate that it is a medium-carbon grade 5 bolt. Six radial lines on a flange bolt indicate that it is a grade 8 alloy steel bolt. Metric flange bolts use class markings instead of radial lines to show the tensile strength of the bolt.
The grade of a flange bolt must match the load that the bolt will experience. If a worker uses an incorrect grade of bolt, the joint may become loose or the bolt may snap. There are many types of flange bolts, and they are used in different application.
Standard hex flange bolts have smooth bases on the bolt. These flange bolts are used on applications where it is important to not mar the finish of the surface. Serrated flange bolts have teeth on the bases of the bolts.
These bolts are used in applications that experience high levels of vibration. Frame flange bolts have extra-wide base. These bolts are used to spread the load on structural steel beams.
The type of bolt that is used in an application depends on the material to be clamped and the vibration that the bolt will experience. Flange bolts can have different torque value depending on the condition of the threads of the bolt. If the threads are dry, there will be more friction between the threads.
More torque is required when the threads are dry. If the threads are lubricated, there will be less friction between the threads of the bolt. Because there is less friction between the threads, a lower torque value should be used when the threads are lubricated.
If the torque value for dry threads is used on a lubricated bolt, the bolt may snap or the threads may become stripped. Before tightening a bolt, it is important to check the threads to see if they are dry or if they are lubricated with oil or anti-seize compound. A specific tightening sequence should be used with flange bolts to ensure the joint is secured properly.
If a single flange bolt is tightened all of the way, it can cause the flange face to warp. Instead, a star or cross pattern can be used to tighten the flange bolts. The flange bolts should also be tightened in stages.
First, the bolt should be tightened to 30 percent of the specified torque. Then the bolts should be tightened to 60 percent of the specified torque. Finally, the bolts should be tightened to 100 percent of the specified torque.
Several precision tool are available to tighten flange bolts to the required torque value. A click wrench is one of the most helpful tool for beginners to use. Digital and beam torque wrenches are the most accurate tools for experienced workers.
Impact guns are used to apply torque to the bolt quick. However, they are not recommended for tightening bolts to the final torque value. With an impact gun, it is easy to apply too much torque to the bolt.
A hand-held torque wrench should be used to ensure that the flange bolts reach the correct torque value. Flange bolts are used in many different important applications. Engine block and cylinder head flange bolts are used to secure the components of an engine and prevent the engine from leaking.
Flange bolts are also used in the structural framing of steel beams. Many types of heavy machinery use flange bolts to secure the panels of the machines to prevent them from vibrating. High-pressure pipe lines use flange bolts to maintain the pressure in the pipes.
Given the importance of these components of the machinery, it is essential that flange bolts used in these applications has the correct torque and grade.
