Tattle Tale Hinge Pins
Checking the Tattle Tale Hinge Pin is a simple process and takes little time or effort to perform and should be performed when the slips are out of the rotary table. Pictures 1 and 2 show how easy it is to insert the gauge in the hollow Hinge Pin. Figure C & D show when the pipe is properly supported. If the pipe is not properly supported, as shown in Figure E the Hinge Pin becomes deformed as shown in Figure F and the gauge cannot be inserted.
Access Oil Tools includes the Tattle Tale Hinge Pin on all SDU and RSDU rotary slips. It is an optional feature on DU style rotary slips. Access Oil Tools has added this simple feature to its SDU and RSDU rotary slips to give the Rental Company or Contractor an advantage in fighting to reduce cost due to damaged pipe.
Drill Pipe Damage
Tatle Tale Hinge Pins Indicate When Pipe is Uneveny Support
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.