With the continuous development of offshore oil and gas fields, pipelines for transporting the amount of offshore oil and gas is growing. Currently coating structure submarine pipelines used mainly 3LPE andFBE. 3LPE long-term use temperature generally does not exceed 70 ℃, short-term up to 80 ℃. As for the transport of crude oil temperature exceeds 80 ℃, use 3LPE coating structure is clearly not meet the technical requirements. While the long-term use temperature FBE coating can reach 115 ℃, to meet the above design temperature requirements, but FBE coating brittle, intolerance mechanical damage in transport and offshore pipe-laying, anti-corrosion coating damage is more serious, Currently subsea pipelines generally do not advocate the use of corrosion in the form of a single layer FBE.

To effectively address transport conditions at high temperature subsea pipeline corrosion problems, foreign countries have been successfully 3LPP coating structure to pipeline, such as the Gulf of Mexico deepwater subsea pipelines and the UK North Sea oil and gas pipelines, etc., are used 3LPP structure, but 3LPP coating applied to subsea pipeline in the country there is no precedent.

Polypropylene has excellent mechanical properties, its yield, tensile, compression strength, hardness, elasticity and wear resistance than the high density and so polyethylene (HDPE) high, and the polypropylene very low water absorption, water 24h The water absorption of only 0.01%, far lower than HDPE. Polypropylene resistant to chemical stability, electrical insulation, and lower density than polyethylene. In terms of heat resistance, long-term use of modified polyethylene at a temperature of -30 ~ 110 ℃. 3LPP is developed on the basis of 3LPE a coating on the excellent performance of anti-corrosion coating. 3LPP 3LPE principle and structure similar to that adopted in the underlying steel fusion bonded epoxy (FBE), to increase the adhesion to the metal, in the middle of a polypropylene copolymer adhesive (PPA) layer, and an outer layer of polypropylene (PP) strong bond, both high resistance to mechanical damage ability, and good resistance to cathodic stripping performance. 3LPP modified by coating structure, the use of temperature above 110 ℃, its excellent resistance to corrosion and high temperature performance to win the broad market prospects, high temperature coating does not make up for other deficiencies, to achieve at a higher temperature and aim at deep water applications, it is emerging more advanced anti-corrosion coating internationally.