Study on Relation between Curing Degree of Epoxy Coating and Glass-transition Temperature of Pipeline

In the updated applicable national specifications in association with using dual-layer fusion epoxy powder method for outer surface corrosion-prevention of the hot-bend pipe for oil/gas transmission, the concept of epoxy powder curing degree has been removed, instead, the glass-transition temperature ΔT_g as measured twice from the heated coating under two testing conditions is used to evaluate the curing condition of the coating.It is pointed out that the ΔT_g value can not be directly calculated, and thus it is necessary to study the relation between the cure percentage and the glasstransition temperature is studied.And the glass-transition temperatures of the epoxy powder T_g3 and T_g4 and their difference ΔT_g are measured by the DSCscanner.And then thecurepercentage C iscalculated with the enthalpy changeremained after thecoatingiscured, and thecorrespondence between the cure percentage C and ΔT_g is fit.And this relation can be directly reflected via the analysis, which can play a quality guiding and promoting role in the manufacturing process of the product.