Cause analysis of drill pipe joint thread galling

A number of drill pipe joint thread-galling failures were discovered in the oil field mentioned, and all of them happened on new pipes, which brings a big loss to oil field economy. Field survey was applied to the failure accident. Mechanical properties test, chemical composition analysis, and micro-structure examination to the joint material and the macro-appearance observation to the tool joint threads were taken. The results showed that, as there was a great central axis deviation of the stands in picking-up process, which caused mechanical damage to the joint threads when make-up, and as the guiding process to make-up was in high speed, the thread galling of tool joints happened eventually. In the end, the prevention methods and suggestions were put forward based on the failure cause.