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Operational Risk Management Advantages from
Premium Corrosion Resistant High Strength Polished
Rods
Dean Murney
NOV Wilson Canada
Abstract
Failures – Everyone wants to reduce them, but they must be identified and then an economic solution
must be found. One failure type, which can sometimes be overlooked is polished rod failures. Most
polished rod failures are fatigue failures that occur just under the clamp. Most of these are a result of
improper placement of polished rod clamps, over torqued clamps, or misaligned clamps/carrier bars. A
paper presented at the 41st annual Southwestern Petroleum Short Course in 1994 concluded that
bending stresses amplified by stress concentrations from polished rod clamps are the most significant
contributors to polished rod failures.
In Canada, NOV Wilson has been running a special metallurgy polished rod which has proven to reduce
fatigue failures due to clamp placement and over torque. This unique high strength – corrosion resistant
polished rod has greater elasticity which handles excessive clamping and/or misalignment through the
carrier bar. It is also homogenous throughout so any damage from scoring does not make it susceptible
to corrosion attack inside the score.
With over 30,000 polished rods installed in Canada, case histories will be presented which will prove the
success in reducing failures with this design.