StopCrackEX - Cold Bolt Expansion Equipment For Arresting Cracks


Many fatigue cracks in bridges and other metal structures are drill stopped to repair them, however, drill stopping may only stop a crack from growing for a short time.


FTI’s StopCrackEX™ System cold expands a pre-fitted, lubricated bushing into a drill stop, supporting the hole and imparting residual compressive stresses around it, protecting it from cyclic loads.


This large zone of residual compression around the drill stop greatly reduces or arrests crack growth, even when the drill stop misses the tip of the crack. Independent, third-party testing has shown that this repair method can extend the fatigue life of the drill stop by over ten times.


Benefits of StopCrackEX


  • Adapted from proven cold hole expansion and expanded bushing technologies developed by FTI for the aerospace industry.
  • Greatly enhances the fatigue life of drill stops, typically by a factor of 10:1.
  • Cost-effective alternative to redesign of the structure.
  • The interference fit bushing induces beneficial compressive residual stress that reinforces the drill stop.
  • Arrests the growth of small cracks around holes.
  • Installed stainless steel bushings provide a positive visual indicator that the drill stop has been enhanced.
  • Reduces maintenance and inspection costs.
  • Effective in all metals including aluminium, steel and titanium.
  • Simple and easy-to-use one-sided operation.
  • A proven system in use worldwide for over 40 years and for 30 years in the UK by Network Rail, in eliminating rail-end bolt hole cracking.

StopCrackEX Enquiry Form

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HIRD Rail Development is a

division of the HIRD Group

HIRD Rail Development


Clifford House

Lady Bank Drive


Doncaster DN4 5NF


P:  +44 (0)1302 952040




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