2 research outputs found
Experimental and analytical studies on the pullout strength of round thread casing connections
497-503Pullout failure is one of the primary
failure modes of API round thread casing connections. Make-up torque and thread
tolerances are the two most important factors that can affect the pullout
strength. In this paper, the pull-out failure process and mechanism are studied
using the finite element analysis (FEA) method. In addition, the effects of make-up
torque and thread tolerances on the pullout strength of API round thread
connections are analyzed. The FEA results are validated through tension tests
on a total of 34 pins and 17 couplings. The results show that pull-out failure
initially occurs at the first and second teeth near the coupling end. At the
same time, thread tolerances especially unmatched taper have notable effect on
pullout strength. The tests show that higher make-up torque levels are
beneficial to the pullout strength. Make-up torque 15~20% higher than the
maximum API limit is recommended when round thread casing connections are used
in oilfield