What are the fastening techniques for Fix Bolts And Flange Bolts?

The tightening technology of Fix Bolts and Flange Bolts is crucial during installation and use, and is related to the stability, sealing and long-term reliability of the connection. The correct tightening technology can not only ensure the safety of the bolt connection, but also improve the operating efficiency of the equipment, reduce failures and maintenance costs. The following are common tightening techniques, which are detailed for the application of Fix Bolts and Flange Bolts:

Preload Control Technology
Preload refers to the initial pressure applied by the bolt during installation. Proper preload is essential for the stability of the connection of Fix Bolts and Flange Bolts. If the preload is too low, the bolt may loosen; if the preload is too high, it may cause the bolt to break or damage the connected parts.
Preload Control Methods:
Torque Method: Use a torque wrench to control the preload through a set torque value. This is the most common method and is suitable for most conventional applications.
Tension Method: Ensure the appropriate preload by measuring the axial tension of the bolt. The tension method is usually used in applications that require higher precision, such as aerospace and high-pressure vessels.
Extension Method: Control the tightening force through the elastic deformation of the bolts, often used in special occasions where high-precision preload is required.
Cross-tightening technology
Cross-tightening is a common flange bolt tightening technology, especially when it is necessary to evenly distribute pressure and ensure sealing. Tighten the bolts in a cross order to ensure uniform force between the flange and the connection surface, and avoid leakage or deformation caused by excessive local force.
Implementation steps:
Start from the center of the flange bolts and tighten gradually around.

Follow the cross-tightening sequence, usually the bolts on the diagonal are tightened alternately, and the torque is gradually increased in multiple times until the specified preload is reached.
Advantages: This method can ensure the sealing between the connection surfaces and avoid leakage problems caused by over-tightening or over-loosening of the bolts on one side.
Segmented tightening method (staged tightening)
For flange connections with high loads or sealing requirements, a single tightening may not be able to achieve uniform preload. The segmented tightening method is to gradually increase the tightening force in multiple stages to avoid damage to the bolts due to sudden high preload.
Implementation steps:
In the first tightening, increase the preload of all bolts to a low value (for example, 50%-60% of the target preload).
In the second tightening, gradually increase it to 80%-90% of the target preload.
The third time, finally increase it to the required target preload.
Advantages: Segmented tightening helps eliminate stress differences between bolts and ensures stable connections. It is suitable for high-precision or high-load applications.
Torque-angle method
The torque-angle method combines preload and angle control and is suitable for tightening applications that require high-precision control. This method first uses a torque wrench to apply a certain torque value, and then uses an angle wrench to further adjust the preload by rotating the angle.
Implementation steps:
Use a torque wrench to apply a preliminary torque first.
Then use an angle wrench to further apply a specific rotation angle to increase the preload.
Advantages: This method can more accurately control the preload of the bolt, reduce the error caused by relying solely on torque, and is suitable for high-precision connection requirements.
Use gaskets and sealing rings
The tightening of flange bolts does not only rely on the tightening force of the bolts themselves, but also usually requires gaskets (sealing pads) and sealing rings to ensure the sealing of the connection surface. These gaskets are usually placed between flanges to help absorb stress and prevent leakage.
Implementation method:
Place suitable sealing gaskets (such as rubber gaskets, metal gaskets or polytetrafluoroethylene gaskets, etc.) at both ends of the flange connection, and ensure that the flange surface is clean and flat.
When tightening the flange bolts, ensure that the gaskets are not damaged and the sealing performance is fully utilized.
Advantages: Gaskets and sealing rings can effectively improve the sealing performance, especially for flange connections in complex environments such as pressure and thermal expansion.
Use locking nuts and anti-loosening technology
Locking nuts (such as nylon locking nuts, double nut locking, etc.) and anti-loosening technology can effectively prevent bolts from loosening, especially in vibrating environments. Using this technology helps to ensure the stability of long-term connections and reduce maintenance costs.
Implementation method:
Use locking nuts containing nylon washers to create friction with the threads to prevent loosening.
For equipment with large vibrations, the use of anti-loosening washers or anti-loosening glue can increase the fixing force of the bolts.
Advantages: Locking nuts and anti-loosening technology can significantly reduce the risk of bolt loosening and improve the safety and stability of the connection.
Use bolt tension monitoring system
In high-precision or very demanding applications, a bolt tension monitoring system can be used to monitor the tension of the bolts in real time to ensure that the preload meets the expected requirements. This system determines whether the correct preload is achieved by measuring the deformation of the bolt (such as elongation).
Implementation method:
Install sensors and measuring equipment to detect the tension of the bolts in real time.
Adjust the tightening force based on the measurement results to ensure that each bolt reaches the ideal preload.
Advantages: This method is suitable for applications that require very high precision and can effectively prevent failures caused by improper preload.
Bolt torque monitoring technology
In some special applications, bolt torque monitoring technology can be used to monitor the torque value of each bolt in real time to ensure torque consistency during the bolt tightening process. This is especially important for multi-point tightening applications (such as flange connections).
Implementation method:
Use torque sensors and data loggers to monitor the torque changes of each bolt.
Adjust the torque according to the monitoring data to ensure that each bolt can meet the same tightening standard.
Advantages: This technology can help improve the consistency of bolt tightening and reduce sealing problems or loose connections caused by uneven tightening.

In the tightening process of Fix Bolts and Flange Bolts, the reasonable selection and use of tightening technology is crucial to ensure the quality of the connection. Through appropriate preload control, cross tightening, segmented tightening, torque-angle method and other technologies, the stability and sealing of the bolted connection can be effectively guaranteed. Combined with auxiliary tools such as gaskets and sealing rings, locking nuts and anti-loosening technology, the safety of the tightened connection can also be improved, especially under complex working conditions such as high load, high temperature and vibration. The comprehensive application of these tightening technologies ensures the wide reliability of fixing bolts and flange bolts in all walks of life.