Abstract
In this paper, long time effect of exposure to highly aggressive, water saturated sour gas containing elemental sulfur at elevated pressure and temperature was evaluated on the diffusion and permeation of a modified Phenolic Novolac Epoxy-Resin film (CEV-236).
No sour gas diffusion was observed after long-term permeation tests (12 and 18 months) of CEV-236. From the results of these permeation tests and Scanning Electron Microscope (SEM) photographs, it appears that the diffusion and permeation rates in this polymer are very low. The high crystallinity and the closed-packed crosslinking of this coating, the geometry and arrangement of the particles of additives (pigment and fillers) in the epoxy network are considered to reflect the high resistance of the system to diffusion and permeation. To assure a good barrier effect of coating systems in sour gas environments, the selected polymers must have a low diffusivity for hydrogen sulfide so that the ability to sorb and be permeated by sour gas can be selectively frozen out. The results show that an efficient way of preventing sour gas from diffusing in coatings is by monitoring the shape and arrangement of inert pigments and fillers as well as the wettability of binding agent.
