Paper: SUCKER ROD COUPLING FRICTION IN HDPE LINED TUBING

Sucker rod coupling friction values are used by rod design software to calculate rod loads for bare steel tubing on steel couplings. The friction values for sucker rod couplings on HDPE lined tubing are not yet known or defined. Therefore, rod load calculations in HDPE lined tubing are problematic. Tests were performed to compare the coupling friction in HDPE lined tubing compared to bare steel tubing at various temperatures and side loads. The objective was to find the drag ratio of rod couplings on HDPE lined tubing to that of bare steel tubing at various temperatures. The data was used to develop an equation to calculate the drag in HDPE lined tubing compared to that of bare steel tubing as a function of temperature. Although not quantitatively analyzed in this study, a side load capacity difference between HDPE lined and bare tubing was also observed