Application Effect of Joint Coating for Oil and Gas Pipeline in Water-Sealed Tunnel

Based on the inspection datas of oil and gas pipeline joint coatings in 6 water-sealed tunnels, the application conditions of hot-melt adhesive heat shrinkable tape joint coating, liquid epoxy joint coating, viscoelastic tape + polymer outer protective tape joint coating were summarized. The reasons for the failure of different joint coating materials in water-sealed tunnel were analyzed. The results showed that a large area of the overall loss of adhesion of heat shrinkable tape joint coating caused sealing failure, the main reason was that the construction quality control was not strict. The application effect of liquid epoxy patch in water-sealed tunnel was relatively poor, the main reason was that water penetrated into the interface between coating and substrate, causing bubbling and severe decrease of adhesion of liquid epoxy coating. The application effect of viscoelastic tape in different water-sealed tunnels was quite different. In some tunnels, the viscoelastic tape had overlapped and improper crimping, resulting in the sealing failure of joint coating.