NANO-TECHNOLOGY FOR IMPROVED DUAL LAYER PERFORMANCE

摘要

Fusion bonded epoxy (FBE) powders and liquid resins are commonly used for corrosion protection of steel pipeline and metals used in the oil, gas and construction markets. The FBE coating should have excellent physical properties to minimize damage during transit, installation and operation. Damage to the coating leads to higher potential corrosion sites on the metallic surface and could ultimately lead to a decrease in service life. During transportation, cinders and grit can get between pieces of the coated substrate so the coating should have superior penetration and abrasion resistance. During installation, the coating should have good impact resistance from back fill or handling equipment. Often the coated substrate is bent during installation, for example to fit the contour of the land, and should be flexible enough to prevent damage to the coating. Once in operation, the coating can be exposed to water and other chemicals and should have good resistance to these chemicals and good cathodic disbondment.rnThere are several ways that have been used conventionally to attempt to make a FBE coating more resistant to mechanical damage. In one conventional approach, the thickness of the overall coating is increased to provide added absorption of impact and abrasion. However, as the thickness of the coating increases the flexibility of the coating decreases. Another conventional approach to enhance damage resistance is to add an abrasion resistant overcoat that has a high filler loading to increase abrasion resistance and decrease impact damage. As with the thicker coatings, higher filler loadings can dramatically decrease the flexibility of the FBE coating. As mentioned above, flexibility of the coating is very important during installation and must be tolerant to bending. Currently available damage resistant coatings force the user to compromise between toughness and flexibility.rnhandling, transportation, and construction. The combination provides the contractor faster installation and the pipeline owner with improved underground coating performance. This paper reviews single-layer FBE, three-layer polyolefin (3LPO) (polyethylene and polypropylene) coatings, and dual-layer FBE (DLFBE). It also demonstrates the performance characteristics of dual-layer FBE pipeline coating systems through test results and case histories for entire pipeline projects. The review includes application and installation specifics. It also introduces nano-technology for improved dual-layer performance.