respectively fig1 furthermore depicts a graph showing stress vs the percentage of tensile yield strength for a grade d drill pipe at the stress relief groove s1 with the standard api groove high stress in terms of percentage tensile yield strength about 50 exists in the areas adjacent the abrupt shoulder 22 and region i and a high stress in terms of tensile yield gradient exists between region i and region ii between point ii and point iii the curve remains substantially uniform with a slight increase in the stress in terms of percentage tensile yield strength curve existing between points iii iv the high stress in terms of percentage of tensile yield strength adjacent the abrupt shoulder 22 and the high gradient thereof between points i and ii indicate the difficulties associated with the prior art in that such stress concentration in the range of 50 of the tensile yield strength significantly decreases tool life fig2 shows a stress relief groove s2 disposed in similar fashion to stress relief groove s1 of fig1 between a threaded end t2 and a tool body p2 with the pipe body p2 having an outer diameter d and an inner diameter id as does the pipe body p1 the threaded end t2 includes threads 30 having a crest 32 and a root 34 with the threads 30 terminating at point 36 the dimension.