Drill Pipe Damage
Tatle Tale Hinge Pins indicate when pipe is uneven
Cause of Damage
Wear or damage to the rotary table, master bushing, insert bowl, and or rotary slip results in improper support of the pipe which causes permanent damage to the pipe. A Rental company or Contractor is seldom aware of this misalignment which results in damaged pipe most commonly in the form of slip cuts.
Figure A below shows a SDU slip located in the insert bowl as it would be in the absence of any wear to the major components. Figure B shows the effect of the same slip seated in a worn bowl.
To address and detect this potential problem, Access Oil Tools utilizes a hollow Floating Hinge Pin and the periodic use of a Hinge Pin Gauge which, when combined, is referred to as a Tattle Tale Hinge Pin.
The Floating Hinge Pin is held centered in a slip hinge pin hole by means of a Hinge Spring Assembly. This design allows the slip segments to move individually and equally, toward the center of the pipe as load is applied. The segments transmit equal force against the drill pipe as the drill string weight increases. This minimizes the effect of uneven loading. Uneven loading is especially noted when, as mentioned above, there is wear in the master bushing, rotary table, insert bowl, slips or all four.
Detection of Damage
In the past, the “solid floating” hinge pin has been used successfully for minor misalignment. By using the Tattle Tale Hinge Pin, the Rental Company or Contractor can detect misalignment before his pipe becomes damaged. All that is required is a periodic insertion of the hinge pin gauge in the hollow hinge pin. If the gauge goes in all the way, then no misalignment is detected. However, if the gauge refuses to go in, it is an indication the hollow pin has been deformed by misalignment of the rotary assembly, and damage to the pipe is sure to result. This periodic check should be performed every two weeks and or when the slips comes in off of a job.