Horizontal directional drilling system with drill string breakout monitoring

A drilling machine comprising:

• a rotational driver for attaching to an up-hole end of a drill string made-up of a plurality of drill rods that are each secured to the next with a threaded joint;
• a first vise configured to secure the drill string extending beyond the drilling machine;
• a second vise configured to secure an up-hole rod at the up-hole end of the drill string;
• a break-out drive mechanism operable when energized to apply torque to the second vise in a joint-break routine configured to rotate the second vise relative to the first vise to break the threaded joint between the up-hole rod and the drill string;
• and
• a control system with a control algorithm for evaluating the joint-break routine, the control algorithm comprising:
• a process for monitoring an operating profile of torque applied to the up-hole drill rod by energization of the break-out drive mechanism during the joint-break routine while the drill string is being held by the first vise,
• a process for monitoring rotational position change at the rotational driver during the joint-break routine,
• a process for characterizing the joint-break routine as normal or abnormal based on the monitored operating profile of torque and the monitored rotational position change at the rotational driver, and
• a process, responsive to the characterizing process characterizing the joint-break routine as abnormal, for interrupting a break-out process for removing the up-hole rod from the drill string and/or providing a notification to a display notifying an operator,
• wherein the control system includes a further control algorithm for distinguishing among at least two different types of abnormal joint-break routines the further control algorithm comprising:
• a process for determining whether the rotational driver was rotated during the joint-break routine, and
• a process for evaluating torque during energization of the rotational driver with the second vise unclamped following the joint-break routine.