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Bolts & Nuts & Bag of Tricks - Engineering's needle and thread

Understanding the Importance of the Turn-of-the-Bolt Method (SANS 10094) in Water Storage Tank Assembly by Savanna Tanks


When constructing Steel Water Storage Tanks, ensuring the structural integrity and durability of the tank is critical, especially since these tanks are used for storing large volumes of water under varying environmental conditions. This is particularly true for Savanna Tanks, a leading provider of Sectional Steel Water Tanks, Galvanized Steel Water Tanks, and Pressed Steel Water Tanks across Southern Africa. The correct assembly of tank panels is crucial for ensuring longevity and safety. One essential aspect of this assembly is the proper tightening of nuts and bolts using the Turn-of-the-Bolt method, as specified in SANS 10094. In this blog post, we will delve into why this method is so important and how it can be applied in practice using an example of an M20 x 55 - 8.8 screw set.


What is the Turn-of-the-Bolt Method?

The Turn-of-the-Bolt method is a widely used procedure for tightening bolts to achieve a specific tension. It is a method specified in SANS 10094 (South African National Standards) and is preferred by Savanna Tanks for constructing Modular Steel Tanks and other Industrial Water Storage Solutions because of its simplicity, reliability, and effectiveness. This method ensures that the nuts and bolts used in the assembly are tightened to the required tension, providing strength, stability, and resistance to external forces.

When it comes to Hot-Dipped Galvanized Steel Tanks or Corrosion-Resistant Water Tanks, the proper application of the Turn-of-the-Bolt method is particularly crucial because it guarantees a secure connection without compromising the protective coating of the bolts, thus preventing premature corrosion. For water reservoirs used in municipal and industrial settings, such as Water Reservoirs for Municipal and Industrial Use, maintaining the structural integrity of every joint is paramount for long-term service and safety.


How is the Turn-of-the-Bolt Method Applied?

To implement the Turn-of-the-Bolt method, the following steps are typically followed:

  1. Snug Tightening: Each nut is initially tightened to a snug condition, defined as bringing the connected parts into firm contact using a spanner or wrench. For a tank structure, this involves the initial tightening to remove any gaps between the connected sections of the steel panels. Savanna Tanks follows this method meticulously during tank assembly to ensure the best fit for their products.

  2. Marking the Bolt and Nut: After the snug-tight condition is achieved, a reference mark is made on the nut and bolt. This mark indicates the starting position of the nut, which will serve as a visual reference for the required rotation.

  3. Final Tightening: The nut is then turned a specified fraction of a rotation (usually 1/3, 1/2, or 2/3 of a turn) as specified by SANS 10094. The degree of rotation depends on the length and diameter of the bolt and the material's grade. This process stretches the bolt to produce the desired clamping force, ensuring that the tank panels are tightly secured.

  4. Verification: Once the turn has been completed, the marks are checked to verify the amount of rotation applied. If the marks do not align as expected, the tightening process is repeated. Savanna Tanks ensures that every bolt is inspected to meet SANS standards, guaranteeing that their tanks perform reliably under demanding conditions.


Example: Applying the Turn-of-the-Bolt Method Using an M20 x 55 - 8.8 Screw Set

To illustrate, let’s consider using an M20 x 55 - 8.8 screw set for assembling a Customizable Water Storage Solution from Savanna Tanks. This type of screw set is commonly used in constructing Sectional Steel Water Tanks and Pressed Steel Water Tanks due to its strength and durability.

  • Bolt Specification: M20 refers to the nominal diameter of the bolt, 55 indicates the length, and 8.8 is the grade, indicating a high tensile strength.

  • Application: When applying the Turn-of-the-Bolt method, the snug-tightened M20 nut should be rotated by 1/2 turn (180 degrees) for a bolt length of 55 mm, as specified in SANS 10094 for grade 8.8 bolts. This rotation ensures that the bolt achieves the required tension to securely fasten the tank panels without damaging the steel or the bolt itself.

  • Result: The final result is a secure, high-tension joint that can withstand the internal and external forces exerted on large water storage tanks, providing a long-lasting and reliable assembly. In Galvanized Steel Water Tanks, this method is particularly effective because it ensures a uniform clamping force, preventing leaks or deformations in the tank structure over time. Savanna Tanks has extensive experience in applying this method to ensure every tank they manufacture meets stringent safety and performance standards.



Why is the Turn-of-the-Bolt Method Crucial for Savanna Tanks’ Water Storage Solutions?

The primary reason the Turn-of-the-Bolt method is preferred for water storage tanks is that it provides a consistent and measurable way to achieve the correct clamping force without relying on specialized equipment like torque wrenches. This is especially important for Industrial Water Storage Solutions and large-scale Water Reservoirs for Municipal and Industrial Use, where uniform tension across all bolt connections is necessary to maintain the tank's shape and prevent any structural weaknesses.

Moreover, for Corrosion-Resistant Water Tanks, ensuring that each bolt is correctly tightened minimizes the risk of water ingress into bolt holes, which can lead to corrosion and compromised structural integrity. For Hot-Dipped Galvanized Steel Tanks, the turn-of-the-bolt method also reduces the risk of over-tightening, which can strip the galvanizing and expose the underlying steel to corrosion.

For Savanna Tanks, employing the Turn-of-the-Bolt method is not just about meeting industry standards, but also about delivering Customizable Water Storage Solutions that stand the test of time, even under harsh environmental conditions. The reliability of this method allows Savanna Tanks to offer high-quality, durable tanks to customers across Southern Africa, including Steel Water Storage Tanks, Modular Steel Tanks, and more.


Conclusion

In summary, the Turn-of-the-Bolt method specified in SANS 10094 is a reliable and effective approach for assembling various types of steel water storage tanks, from Sectional Steel Water Tanks to Modular Steel Tanks and more. By applying this method correctly, Savanna Tanks ensures that their tanks remain structurally sound and durable, providing safe and long-lasting water storage solutions for both municipal and industrial use. For complex installations involving large tanks, such as Customizable Water Storage Solutions, following the SANS 10094 standards not only ensures compliance but also guarantees that the tank will perform optimally under all operating conditions.

With a reputation built on quality and adherence to best practices, Savanna Tanks stands out as a leader in the industry, providing robust, high-quality water storage tanks that meet the needs of diverse applications.



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