Abstract
Evidence mounts: field-applied welded overlays have provided protection of internal surfaces in a wide variety of process vessels with good success. Experience within the petroleum industry has been quite varied. Completed projects include work in various types of trayed columns, vacuum columns, FCCUs, autoclaves, alky units, tanks, drums, reactors, coker units, and others. These vessels have been constructed out of a wide variety of materials: carbon steel (A285-C, A515, A516, etc.), 1-1/4 Cr-1/2 Mo, 316L, 317L, carbon-1/2 Mo, 405 fused clad, 316L fused clad, and even Hastelloy C-276! Among the overlay materials employed on these projects has been a variety of 300 series stainlesses including 309LSi, 317L, and 310MoL (904L). Several nickel based materials such as Inconel 82, Inconel 625, and Nickel 61 have been employed. And other materials such as 18/17E, 30/40E, Monel 60, 22.8.3L, 25.22.2, and Hastelloy C-22 have been used in some situations. These vessels have been as thin as 1/4 to 3/16" and as thick as 12". Applications have proven effective in situations calling for as little as 29 square feet and as much as 8400 square feet. Work has been accomplished in a wide variety of environmental situations -from caustic to acidic, in H2S, in chlorine, in heat, in cold, in fair weather, and in hurricanes. This paper will discuss how overall quality can be maintained in these applications. Topics include inspection practices, surface preparation, qualification of personnel and weld procedures, as well as other key considerations.
