Failure Analysis

Mechanical Failures

Mechanical failures account for a large percentage of the total number of all rod string failures. Mechanical failures include every type except manufacturing defects and stress/corrosion fatigue. Mechanical damage to the rod string contributes to a stress raiser which will cause sucker rod failures. The time to failure will be influenced by many variables, of which maximum stress, operating environment, orientation of the damage, sucker rod chemistry, sucker rod heat treatment type, stress range and type of damage will be of the most important. Mechanical damage can be caused by inept artificial lift design, improper care and handling procedures, careless makeup and breakout procedures, out-of-date operating practices, or any combination of these elements.