1、,anti-corrosion protection of buried pipelines,-Anti corrosion coatings,,Contents,,,Selection of the most economically effective technique for minimizing the effects of corrosion is a critical design decision. This course will review fusion bonded-epoxy (FBE) coating solutions for corrosion mitigati
2、on of pipeline systems,,1.the function of coating,Using these systems is vital to protect steel. Coatings help prevent corrosion by providing: (1)Sacrificial or galvanic protection. (2)Passivation of the steel (inhibitive pigments). (3)A barrier against the environment.,,Various types of coating,Coa
3、tings of pipelines:Hydrocarbon bitumen (hard coal tar, asphalt)Polyethylene (2 or 3 layers)PolypropyleneEpoxy（环氧树脂）Polyurethane foam (聚氨酯泡沫) Coatings of fittings:Polyurethane or Modified Polyurethane (projected)Moulded resins Polyurethane（成型树脂聚氨酯）,,Field joints coatings (welded joints) （现场对接/连接接头）Po
4、lyethylene tapes（聚乙烯胶带）Shrink sleevesPolypropylene Mechanical protectionPolyethylene coatings: 3 layers (PE 3L),,Functions of the anticorrosion coating,,Coatings for pipelines,,Field joint coatings (welded joints),,Components of insulated pipeline,,Complementary mechanical protection,These protectio
5、ns are used complementary to the anti-corrosive coating:- in rock ground,- when concrete saddle are necessary The mechanical protections have to satisfy to particular tests:- indentation and impact,- absorptivity in aqueous environment,- resistance to the attack by micro-organisms,,Complementary mec
6、hanical protection,,Fusion Bonded Epoxy (FBE)Field,FBE coatings have been in use for underground and undersea pipeline protection for nearly forty years.,,A significant advantage of FBE coating systems is that the same materials can be used on the girthweld as on the rest of the pipe,,Three-layer po
7、lyolefin（聚烯烃） coating systems utilize FBE as the primary corrosion barrier.,,FBE internal pipe coatings provide corrosion protection as well as improved fluid flow.,,Fusion Bonded Epoxy (FBE)Field Joint Coating,,2. mechanisms and characteristics of various coatings,a.Sacrificial coatingsZinc-rich pr
8、imers are applied at 3.0-mil dry-film thickness to provide galvanic protection. the zinc will dissipate before the steel is attacked. Adequate high-performance topcoats are recommended to prolong the life of the coating.,-mil密尔（千分之一英寸） Zinc-rich primers富锌底漆,,b.Corrosion inhibitors,Most paint primers
9、 contain a partially soluble inhibitor pigment, e.g., zinc chromate, that reacts with the steel substrate to form the iron salt, Such salt slows down corrosion. Chromates, phosphates, molybdates, borates, silicates and plumbates are commonly used.,zinc chromate:铬酸锌phosphates磷酸盐；molybdate钼酸盐； borates
10、硼酸盐； silicates硅酸盐；plumbate高铝酸盐； alkalinity碱性,,c.Barrier coatings,Protective coatings are the most widely used and recognized forms of barrier material. Barrier coatings are effective because they keep moisture and oxygen away from the steel substrate.,barrier coating防护涂层； brick linings砖衬里 barrier ma
11、terial 阻隔材料,,4.Implementation of the coating on site,Implementation of a coating on field joint (welding),Coating of a support,,Implementation of the coating on line,Coating control with the holiday detector after implementation,,Repair of a coating after localisation of coating defect and excavation,Control of the coating before backfilling,,Thank You !,,
