Epoxy Powder Coating For Oil And Gas Pipeline

Pipeline transportation of oil and gas has a history of more than 100 years.The pipelinecorrosion has always been a major challenge and restricts its development.Fusion bond epoxy powder coating(FBE)has become the important anti-corrosive coating for pipes due to its excellent adhesion,anti-corrosive performance and mechanical properties.The materials,formulation and coating process are the determinant for properties of epoxy power coating.In this study,a new formulation of epoxy powder coating with excellent anti-corrosion performance was designed by analyzing and selecting the resin,curing agent,modifier,filler and auxiliary agent.Meanwhile,an appropriate process for powder preparation and coating process was designed.The main contents are as follows:(1)The anti-corrosion performance of pure epoxy system,epoxy/polyester system and pure polyester system powder coating was analyzed.It was found that the epoxy powder coating had excellent anti-corrosion effect on pipeline.Compared with the traditional bisphenol A epoxy resin,phenolic modified epoxy resin has more epoxy groups,and the corresponding coating has higher crosslinking density and better corrosion resistance.The experimental results show that phenolic resin reduces the flexibility of the coating.Therefore,the pure epoxy powder coating without phenolic resin should be used in the surface layer of double-layer hot-melt bonded epoxy powder coating.(2)The effect of curing agent on the properties of pure epoxy powder coating was analyzed.It was found that dicyandiamide as curing agent the coating had higher crosslinking density,better compactness and better corrosion resistance than that of phenolic curing agent.It is difficult to open the N-H bond of dicyandiamide curing agent and the reaction rate is slow.It is necessary to add catalyst to improve the curing rate.(3)The effect of fillers on the properties of the coating was studied.Silicate fillers such as wollastonite and mica powder had better corrosion resistance than barium sulfate and calcium carbonate fillers,and the optimum addition amount is 30-35%.Adding HDPE wax powder can effectively improve the scratch resistance of epoxy powder coating,and has little effect on other properties,and the optimum addition amount is 2%.(4)The preparation and process of coating were discussed.The residence time and temperature of materials in extruder should be controlled.Before coating,the substrate should be sandblasted and preheated to 230-240?.For single-layer FBE coating,the appropriate coating thickness is 300-400?m,while for double-layer FBE coating,the appropriate thickness of bottom layer and surface layer is300-400?m and 400-500?m,respectively.(5)The prepared powder coating has been applied to oil pipeline project in Australia with good performance.