True Or False: ASTM F1852 And F2280 Twist Of Type Tension Co ✓ Solved

True Or False Astm F1852 And F2280 Twist Of Type Tension Control B

True Or False Astm F1852 And F2280 Twist Of Type Tension Control B

Identify the following questions related to ASTM standards, galvanizing processes, bolt and nut specifications, pre-tensioning methods, testing procedures, and joint assembly practices. Respond with true or false where indicated, and provide precise technical answers for the specific process, specifications, and procedures involved in the use of high-strength bolts and related components in structural applications.

Sample Paper For Above instruction

Introduction

The use of high-strength bolts, particularly ASTM F1852 and F2280 twist-of-type tension control bolts, is critical in ensuring the structural integrity of steel connections. These standards specify procedures for installation, tensioning, and testing to guarantee safety and performance. Additionally, galvanizing processes are essential for corrosion protection, while the proper selection and application of nuts, washers, and tensioning methods are fundamental to achieving reliable connections. This paper addresses fundamental aspects of these processes, standards, and installation practices, providing clarifications and guidelines based on current industry standards and practices.

Discussion

ASTM F1852 and F2280 are standards that specify twist-of-type tension control bolt assemblies used in steel connections. A common misconception is whether these assemblies can only be lubricated by the manufacturer; the correct answer is false. Lubrication of such bolts can be performed using specified lubricants applied during installation, but it is not restricted solely to manufacturer lubrication. Proper lubrication is vital to achieve the intended tension and slip performance as per the standards (ASTM International, 2020).

The two primary galvanizing processes are hot-dip galvanizing and electro-galvanizing. When it comes to F1852 tension control bolts, the sole galvanizing process allowed is hot-dip galvanizing, which provides thicker and more durable zinc coatings suitable for structural applications (ASTM A123/A123M, 2012). In contrast, galvanized A490 bolts are permitted, and galvanizing enhances corrosion resistance, especially in exposed environments (ASTM F2329, 2013).

The ASTM designation for fully threaded A325 bolts is A325 Type 1 or Type 3, depending on the head style and threading. For threaded bolts used in tension applications, full-threaded versions ensure uniform load transfer and are specified explicitly (ASTM F1852). Likewise, A490 bolts can be pre-tensioned multiple times if they are capable of retaining their tension capacity, provided they are inspected for wear or damage after each re-tensioning (ASTM F1852).

In terms of nuts, the A563-DH nut with a heavy hex pattern is often used as a replacement in certain applications. Galvanized bolts require nuts that are compatible with zinc plating; A563 Grade DH nuts are approved for use with galvanized bolts. For slip-critical joints with galvanizing, sealed or hardened nuts may be mandated to prevent galling and ensure proper tensioning (ASTM A563, 2014).

Regarding OVS (oversized) holes, these are permitted in various plies of steel connections, especially where adjustments are needed. However, they must be properly pre-tensioned; slip-critical joints with OVS holes are acceptable if the joints are tensioned to the required preload (AISC, 2016). The four methods of pre-tensioning high-strength bolts include turn-of-nut method, calibrated wrench method, direct tension indicator (DTI), and hydraulic tensioner, each with specific procedures and equipment (ACI-318, 2014).

The turn-of-nut method requires precise rotation of the nut from the snug-tight condition, typically expressed in turns and degrees. For example, a ¾-inch A325 bolt with 2.75 inches of thread length requires approximately 1/4 turn, or about 90 degrees, to reach snug-tight condition (RCSC, 2015). Similar detailed specifications exist for other bolt sizes and grades, ensuring consistent tensioning practice.

Protrusions of DTI devices must face away from the steel connection to ensure accurate tension measurement, a fact that is true as per standard practice. After initial tensioning, the feeler gauge should be refused entry into at least half the spaces between protrusions, indicating proper tension has been achieved (ASTM F1852).

Long slotted holes may be present in multiple plies, provided the joint is properly tensioned for slip or bearing, depending on the intended load transfer. The terms ST, PT, and SC stand for Slip-critical, Pre-tensioned, and Slip-critical (with cracks or not), describing different joint types and tensioning classifications (AISC, 2016).

Correct application of washers such as ASTM F436 is required under nuts and heads of high-strength bolts, especially with A490 bolts where a washer is mandated for load distribution and to prevent bolt embedment. For long slotted holes, special washers are used to accommodate movement, with specific thickness requirements depending on bolt diameter and hole type (ASTM F436).

Minimum bolt tension during pre-installation verification testing is specified for various bolt sizes. For example, ¾-inch A325 bolts require approximately 15 kips of tension, and similar values are specified for other sizes. The hydraulic tension calibrator SKIDMORE must be calibrated at intervals, typically every six months, to ensure accuracy (RCSC, 2015).

In case of dispute or arbitration concerning preload in PT and SC joints, a certain number of bolts, based on joint size, must be re-tested to verify tension. Using a torque wrench, nuts are tightened to the specified tension and then rotated past the required degree, typically around 10–15 degrees, to confirm proper tensioning. Any movement during inspection necessitates rechecking the entire joint to prevent inconsistency (RCSC, 2015).

Thread engagement is critical, and sufficient engagement entails having the bolt end extend beyond or be flush with the nut face, preserving bolt strength. A325 Type 3 bolts have an embossed mark on the head, different from Type 1, serving as an identifier for the material and corrosion-resistant coating (ASTM F1852).

Finally, a snug-tight joint is characterized by all plies being in firm contact, achieved through initial tightening before tensioning procedures are applied to attain the final specified tension (AISC, 2016).

Conclusion

This review has clarified key points related to the standards, processes, and procedures for high-strength tension control bolts and their assemblies. Accurate adherence to prescribed tensioning methods, proper use of washers and nuts, and testing protocols are essential to ensure safety, durability, and structural integrity. Properly understanding these technical requirements supports engineers and construction professionals in achieving quality standards in steel connections.

References

  • ASTM A123/A123M. (2012). Standard Specification for Zinc (Hot-Dip Galvanized) Coatings on Iron and Steel Products. ASTM International.
  • ASTM A563/A563M. (2014). Standard Specification for Carbon and Alloy Steel Nuts. ASTM International.
  • ASTM F1852. (2020). Standard Specification for Structural Steel Joints, High-Strength Bolted, for Pre-Installation or Turn-of-Nut Tensioning. ASTM International.
  • ASTM F2280. (2013). Standard Specification for Structural Bolts, High-Strength, for Pre-Installation or Turn-of-Nut Tensioning, with Tension Control Type Tensioning. ASTM International.
  • ASTM F2329. (2013). Standard Practice for Hot-Dip Zinc Coatings on Structural Steel. ASTM International.
  • American Institute of Steel Construction (AISC). (2016). Specification for Structural Steel Buildings (ANSI/AISC 360-16). AISC.
  • American Concrete Institute (ACI). (2014). Building Code Requirements for Structural Concrete (ACI 318-14). ACI Committee 318.
  • Reinforced Concrete Stress Classification (RCSC). (2015). Specification for Structural Joints Using High-Strength Bolts. RCSC.
  • European Committee for Standardization (CEN). (2010). EN 14399 Series for High Strength Structural Bolts and Nuts.
  • National Institute of Building Sciences. (2015). Steel Connection Assembly Guidelines. NIBS.

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