There has recently been an increase in the use of structural hollow sections as columns in multi-story construction projects. This increase is due to the aesthetic, economic and structural performances that these hollow sections can provide for for engineers. The only downfall to this type of construction is the inability to access the interior of the sections to allow for the tightening of a standard bolt. Due to this, there was a need to develop a blind fastening solution that will ensure a structurally sound connection.

The Original BoxBolt®

The BoxBolt® is a convenient & reliable blind fastening solution for connecting to hollow sections of steel or where access is restricted to one side only. The BoxBolt® is fully tested and approved for us with rectangular, square and even circular hollow sections. Featuring a hexagonal head design, that aids in the installation process. The hex head allows it to be held in place with an open ended wrench, while the core bolt is being tightened by a torque wrench. As the core bolt is being tightened, the threaded wedge is drawn up inside the body, expanding the fins, creating a secure connection.

*You can use the one piece accessory called the BoxSok™ when installation time is at a premium.

Features and Benefits:BoxBolt

  • Simple connections to round, rectangular and square sections
  • Guaranteed safe working load
  • 5:1 factor of safety
  • No close tolerance holes required
  • Only standard hand tools required
  • Available in mild steel, zinc plated or hot galvanized and stainless steel
  • Large combined material clamping range
  • Custom Tamper-Resistant BoxBolt & Special Lengths Available

BoxBolt® Options Available

Available in (3) finishes: Zinc Plated for less aggressive environments, Hot Dip Galvanized for the more aggressive environments and Stainless Steel for the most demanding of applications. Available in (3) lengths, making BoxBolts extremely flexible to suit its environments and application needs.

  • MaterialsBox-Bolt-Dia
    • Mild steel to BS EN 10083 Grade 1.1151
    • Stainless steel to BS EN 10088 Grade 1.4401
  • Finishes
    • Zinc plated to BS EN 12329 : Class Fe//Zn8//A
    • Hot Dip Spun Galvanized to BS EN ISO 1461
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BoxBolt® Approvals

The BoxBolt® is approved for use by Lloyds Register (LR) type approval and the Deutsches Institut fur Bautechnik (DIBt) to give the specifier and user total confidence.

Hole Dimensions and Positioning



The loads stated above are based on the LRFD (Load & Resistance Factor Design) method recommended by the AISC for bolted steel connections. This uses a factor of 0.75 of the ultimate load and therefore equates to a 1.33 to 1 factor of safety that we have applied to our published loads above. The overall strength of the connection is governed by the strength of material our BoxBolt is connecting into; therefore, this should be checked for structural capacity by a structural engineer.
Approvals – The published loads are taken from physical testing in hollow structural section which are then verified by Lloyds Register Type Approval. The BoxBolt is also tested and approved by DIBt (Deutsches Institut fur Bautechnik) which complies with the DIN 18800 and Eurocode 3 design methods for bolted steel connections. A design guide and calculator is available when using these methods. Please ask our technical team for more information.