If you have ever had a pin thread break or perhaps the box shoulder has flared or mushroomed, then you might have a problem with make up torque.
Make up torque is the recommended amount of torque to apply when tightening your drill pipe prior to running it down the hole. The amount depends on the connection, the inside diameter of the pin, and the outside diameter of the box.
A lot of common thread problems can be traced back to improper make up torque. If too little is applied (running loose), then connections could continue to tighten during drilling and over tighten (over torque) causing box shoulders to mushroom and pins to stretch and/or break (Think of an impact wrench). Too much torque applied at the table can lead directly to mushrooming & pin breakage.
The important aspect is that the connections are tightened prior to running. I don’t care if you’ve been drilling for 80 years and not tightening your connections at the table, you are not doing it right. Like when I drive the narrow, curvy road to town at 70 mph. I haven’t crashed but it isn’t the safest, best method.
On some rigs, the amount of torque applied is registered on a pressure gauge in psi designations measuring hydraulic pressure instead of torque amounts such as foot pounds. In these cases, you need to contact the rig manufacturer for a reference chart matching your rig’s psi to foot pounds of torque. If you do not know the proper make up torque for the drill pipe you use, lease contact us.
As always, keeping your threads clean & well lubricated with a good grade of tool joint compound is essential to long, trouble free make & break.
This is a torque chart for the 2 7/8 IF (NC31) connection (taken from the Grant Prideco catalog). For a 4 1/2″ Flush Joint drill pipe with the 2 7/8 IF and a 2 1/8″ ID, the make up torque is 6400 foot pounds. Values are pin strengths except where noted with a “B” where the box is the weaker member. Notice that the tension ratings as ultimate Tensile Strength of a drill pipe is typically determined by the tubes (4 1/2 x .337 E75 has an ultimate tensile strength of 330,000 lbs).