Pipe internal coatings have been developed and used to improve flow efficiency and corrosion
resistance of production lines. Accelerated laboratory tests were performed to evaluate the mechanical
and environmental resistances of two commercial coatings used in a 135S 5-inch-OD drill pipe. The
parameters evaluated include resistances to torsion, flattening, abrasion, and tension, and resistance of
one coating to pipe corrosion in high temperature and pressure brines which: (1) have a high pH, (2)
contain CO2, or (3) contain CO2 and H2S. No sign of failure of both coatings was observed after tensile
loading test. The wear resistance was below 2.2 liter/µm for both coatings, although the wear patterns
after abrasion test were shown to be irregular. After torsional loading and flattening tests, the coatings
were shown to have limited degradation, in the form of delamination and disbondment. Examinations of
the samples after environmental tests, under 30x optical microscope, showed no coating delamination,
while the coating color changed slightly.
Keyword: drill pipe, internal coating, corrosion, production, wear resistance