Paper: How to Minimize Polished Rod Breaks

Sucker rod breaks have been extensively studied and documented in the oil industry. Polished rod failures, on the other hand, have not received as much attention. As a general rule, operators seem to be more tolerant of polished rod failures. But polished rods fail for reasons that can be controlled. The purpose of this paper is to identify these reasons and to discuss ways to minimize polished rod breaks. Almost without exception, the polished rod is the strongest component of the rod string. It has the largest cross-sectional area and its material strength is at least equal to that of the sucker rods. Yet in many cases, polished rods fail with regularity while the sucker rods do not. Surface pumping equipment can induce destructive stresses in polished rods. By analyzing polished rod failures, which usually occur at the bottom of the polished rod clamp, useful conclusions can be reached about these stresses and what can be done to control them.