DuPont Powder Coatings, manufacturers of Nap-Gard® fusion-bonded epoxy (FBE), has recognized and attested to the value of Xiom's flame spray powder-coating system in repairing and welding pipelines in the field. (Currently, the Nap-Gard® powder is used to coat and repair carbon steel pipeline in traditional baking ovens.)
The tests suggest that Xiom's portable spray gun powder-coating technology can alleviate the field-weld coating application problems associated with Tengiz's harsh winter weather, as well as cut the cure time from days to minutes. Located in low-lying wetlands along the northeastern shores of the Caspian Sea south of Russia, the environment at Tengiz is extremely corrosive with soil that is sandy and soggy with salty sea water.
Moreover, temperatures ranging from -40º in winter to 40ºC in summer cause cyclical freezing and thawing. To provide optimum corrosion protection, the 39-ft. carbon steel pipe lengths are factory-coated with DuPont Nap-Gard® FBE red primer and gold top coat. The pipe lengths are then shipped to the Tengiz site where they are welded together in the field.
"With the Xiom portable powder spray-coating technology, it is now possible to take the entire system, the solutions and the savings right to the projects," says Andy Mazzone, Xiom CEO. "Working with DuPont's Nap-Gard® coatings and Xiom's portable spray guns will greatly increase efficiency, yielding enormous savings in costs and time."
After researching alternative coating materials and applicators for girth welds and repairs, NACE International-certified and TCO senior coating inspector John Shields, along with the coating contractor, decided to field test Xiom's portable polymer spray system.
A series of field tests were conducted on 6-in. carbon steel pipe with simulated weld and repair areas. The Xiom 5000 Scorpion gun was used to cover the larger girth welds and damaged areas with the same DuPont thermoplastic powders used to coat the pipe lengths in the factory. The test spray coating overlapped the existing coating to form a monolithic bond.
"The trials carried out so far look very promising using the DuPont Nap-Gard® dual FBE," according to Shields.
"The process doesn't just 'melt' the FEB powders," explains Ian Lester, who is supervising the tests, from Xiom-Europe. "The heat releases a catalyst and initiates a chemical reaction that cures the two-coat system. It changes the molecular structure of the thermoplastic material, and the molecules in the material are bonded together. The powder does not char or burn during application because the system wraps the polymer powder in a stream of cooling protective air to prevent the particles from overheating."