HiLo Open Gap Tool

Client Requirements

When welded, SCRs and other fatigue-sensitive pipes require a very small internal mismatch in geometry known as a HiLo gap, which is typically less than 0.5mm. Any measurements taken should therefore be accurate to at least 0.5mm. In the past, measurement tools have offered poor repeatability and accuracy and required a two-step process.


OMS has developed a tool that solves these accuracy and repeatability issues and is faster to use. The PipeChecker™ Open Gap HiLo Tool measures the internal HiLo of an open gap bevelled pipe joint. The tool uses a standard digital micrometer to measure the HiLo mismatch in a single operation.

This tool replaces less accurate manual Vernier systems that are more difficult to read. Open gap welds are normally aligned by using external line-up clamps, which means the tool has to fit into a relatively small space.

To operate the tool, the user pushes the blades into the gap between the pipes and turns the blades through 90 degrees. As the head is pulled up, the blades make contact on either side of the gap, enabling the HiLo difference to be measured. As the head is constrained by the plunger slide, the tool is repeatable, accurate and also prevents manual errors.

Benefits to the Client

  • Internal HiLo measurements
  • Higher accuracy (to 0.05mm) & repeatability than existing methods
  • Easy to use, industry standard digital gauges
  • Hold button
  • 180-degree head rotation for easy reading at different angles
  • Calibration/verification stand
  • Traceable measurements
  • Data logging software & Bluetooth versions are available
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