Expansion sleeve coupling bolts

Bolted coupling
challenges resolved!

Utilizing stringently tested and proven technologies, Superbolt expansion bolts are truly fitted into the hole due to radial expansion of the conical bore sleeve. By design, accurate radial force combined with the known axial clamping load provides total protection against coupling slippage and thus prevents bolt / hole damage during subsequent removals.

Superbolt range of hydraulic (HyFit) and mechanical (EzFit) expansion bolts offers a wide range of flexibility in application - suitable for through hole couplings, bling hole couplings - even applications requiring accurate location of components without axial load. The expansion bolts can be retrofitted to replace traditional interference or force fitted bolts most reliably and cost effectively.

  • Damaged hole from a 660MW Steam Turbine Coupling, 90mm diameter.

The challenge with fitted coupling bolts

The installation and removal of traditional fitted coupling bolts can be difficult, problematic, time consuming and hugely expensive in terms of extended downtime. For example, it can take 3 full days for a destructive removal process of the bolt, causing extensive damage to the coupling hole and increasing reparation cost (see top image on left).

Understanding the widely varying needs for efficient coupling design and maintenance, Superbolt expansion bolts are designed to guarantee ease of installation and removal, stops coupling slippage and prevent unplanned downtime.

By pulling a taper body bolt through a taper bore sleeve, the sleeve expands to completely fill the coupling hole, hence becoming a truly fitted bolt. Superbolt offers both hydraulic and mechanical expansion sleeve coupling bolts to best suit our customers and their application requirements.

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For all designs of couplings

The principle of Superbolt expansion sleeve coupling bolts is to ensure that simplicity of installation and removal is ensured. By installing and removing the bolt and sleeve assembly in the clearance condition, coupling bolt or hole damage cannot possibly occur.


  • Truly fitted bolt with radial expansion
  • Safe, reliable and easy removal / installation
  • No coupling slippage
  • No hole damage or re-machining
  • Easy retrofit package
  • Compact, ergonomic tooling
  • Accurate maintenance scheduling


Unique features and advantages of both hydraulic and mechanical expansion sleeve coupling bolts can be combined to best suit specific requirements.


Take your coupling bolt to the next level

HyFit hydraulic expansion bolt is designed to deliver high performance torque transmissions for critical load rotating shafts and couplings and increases safety during the process. It is an advanced product with high design capability for all types of couplings requiring truly fitted bolts. HyFit is commonly used for Steam and Gas turbines, Marine propulsion drive couplings and all heavy rotating plants.

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Solution for large flange coupling

EzFit mechanical expansion bolt achieves true fit into the hole, ensuring simple coupling make up / break out procedures. It is a long established product with design capability for all types of coupling requiring truly fitted bolts, commonly used for Hydro turbines, Marine propulsion drive coupling, large motors and gear rings that require component location accuracy.

Click here for more information about EzFit