Drill pipe tensile load capacity

Determine the tensile load capacity of a 4 4in., 16.6-lb/ft, steel grade X-95 new drill pipe subjected to a rotary torque of 12,000 ft-lb if the required safety factor is 2.0. 

Substituting Equations 4-59, 4-60, 4-56, and 4-55 into Equation 4-54 and solving for the tensile load capacity of drill pipe yields... 

Find the tensile load capacity of 5-in., nominal weight 19.5-lb/ft, steel grade E, premium class drill pipe exposed to internal drill pipe pressure = 3,000 psi and rotary torque T = 15,000 ft-lb. 

The reduction in the tensile load capacity of the drill pipe is 311,400 -260,500 = 50,900 lb. That is about 17% of the tensile drill pipe resistance calculated at the minimum yield strength in uniaxial state of stress. For practical purposes, depending upon drilling conditions, a reasonable value of safety factor should be applied. 

Normally, not more than two sections are designed but, if absolutely necessary, even three sections can be used. To calculate the tensile load capacity of drill pipe, it is suggested to apply Equation 4-58 and use the recommended makeup torque of the weakest tool joint for the rotary torque. 

From Table 4-80, the minimum tensile load capacity of selected drill pipe P, = 501,090 lb. 

The tensile load capacity of drill pipe corrected for the effect of the maximum allowable torque, according to Equation 4-58 is... 

To evaluate the load capacity of drill pipe (e.g., allowable tensile load while simultaneously a torque is applied), the maximum distortion energy theory is... 

---