His frustration was compounded by the fact that the stainless steel hand railings around and inside the pool were in flawless condition, even though their exposure environment of immersion, splash and spill was more aggressive than what the rusting duct above was exposed to. When bits of rust started falling into the pool, the exasperated facility owner took action. Six months after the facility opened, telltale spots of red and white rust corrosion product started forming on the duct’s joints and connections-and started to spread. The concrete ceiling above the expansive indoor pool was coated with a white epoxy, and carried a large (5+ feet in diameter) stainless steel air duct. The Case of the Not-So-Stainless Indoor Pool Duct That’s what the intrepid inspector found when called to investigate a problem at an upscale handsome new pool complex. Such grades may require a rust-inhibitive primer or system for protection just as mild steel would. However, it is important to note that all stainless steels are not created equal: there are various grades of stainless, and cheaper grades will corrode when exposed to marine environments, chemicals, or high humidity. if the architect wants to change the color). Stainless steel is often used without a coating except for esthetic purposes (e.g. This is “stainless” steel and there are different types and grades that vary widely in corrosion resistance, strength, and performance properties common types include austenitic, ferritic, martensitic, and duplex. But when enough chromium (more than about 10%) is added to ordinary steel, the oxide produced on the surface is a very thin, virtually invisible layer that provides protection from a wide range of corrosive media. In the presence of moisture, ordinary carbon steel forms iron oxide (rust) rust is not protective and eventually the entire piece of steel will corrode and be converted to rust. Their remarkable resistance to corrosion comes from the chromium-rich oxide film that forms on the surface. “Stainless“ steel is the name given to a group of corrosion resistant and high temperature steels that possess in excess of 10.5 - 11% chromium content. It is also recommended that more extensive work be conducted to verify these findings.Excerpted from MPI’s Coatings Specialist training and the experience of Paint Quality Assurance Inspector Dave Lick From the information obtained, it is recommended that consideration be given to the elimination of the passivation requirement for stainless steel. Based on the above, we started a laboratory investigation to determine if the elimination of the passivating procedure will have an adverse effect on the camouflage paint system. Many companies are not passivating the corrosion-resisting steels before the application of wash primer. Federal, state and city environmental and/or health regulations may prohibit the use of hexavalent chromium-one of the components of the passivating formulation used for the treatment of corrosion-resisting steels. 117 for metals), metric, or MIL-C-8514, Coating compound, metal pretreatment, resin-acid. It also states surfaces to be painted shall be treated with wash primer conforming to DOD-P-15328, Primer (wash) pretreatment (Formula No. ry specification MIL-T-704, Treatment and paint of materiel, requires the passivation of corrosion-resisting steel surfaces before painting.
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