Slip Crushing

In the early 2000’s when slip crushing became a point of concern for subsea wells, Workstrings Engineering began testing slips on actual drill pipe and calculating the slip crushing capacity limits of pipe with the associated slips.

Workstrings was the first company to test drill pipe slips on actual drill pipe with a series of internal strain gauges.

  • Slip Capacity = the static load rating that designates when the slips may become damaged
  • Slip Crushing Capacity = the calculated static load that designates when the slips can damage the pipe

Workstrings’ Slip Crushing Analyzer determines the maximum load that can be placed on the slips without damaging tubulars subjected to a tensile load.

The calculation is dependent on the actual slip design, length of die contact to the pipe, the drill pipe dimensions and yield strength. The calculation has been confirmed by a series of load tests and thousands of designs with ZERO failures.

  • Landing String Design will evaluate slip crushing for all casing and liners in the well. Workstrings maintains the largest global fleet of landing strings.
  • Drill String Design will evaluate slip crushing capacity for each hole section and calculate the slip crushing at each segment of the drill string.
  • Completion String Design will evaluate the slip crushing for each segment of the completion string.
Top view of actual slip testing set-up

Slip Crushing Theory & Calculations

Variables in Spiri-Reinhold Equation

  • Length of Contact
  • Radial Contact
  • Angle of Contact
  • Friction Coefficient between bowl and slips
  • Pipe grade and dimensions