Mechanical and Environmental Evaluation of Two Internal Pipe Coating Systems Used in a 5-inch Drill Pipe

Internal coatings have been developed to improve the flow efficiency and corrosion resistance of production pipes.  Laboratory tests were conducted to evaluate the performance of two commercial coatings in a 5-inch-OD drill pipe. The evaluation parameters include mechanical resistance of the coatings to torsion, flattening, abrasion, and tension, and their corrosion resistance after exposure in brine containing CO₂ and/or H₂S under high temperatures and pressures. No sign of failure for both coatings was observed after the tensile loading test. Although the wear pattern after abrasion test was shown irregular, the wear resistance values of both coatings were shown within acceptable limits. After the torsional loading and flattening tests, the coatings were shown of limited degradation in the form of delamination and disbondment. Examinations of the samples after environmental tests, through first visual inspection followed by examination under 30x optical microscope, showed no coating delamination, although the color of the coatings was turned into a slightly different color.