When thinking about the safe operation of boilers (and don't we all?), several systems can readily be named; flame control, fuel/air ratio; steam pressure control, levels in the vessel, etc. What about the water? It seems so passive, as long as there is enough for level control, what's the big deal? Well, it turns out, that as the steam produced by a boiler is used in the process, the condensate from that steam is returned to the boiler as feedwater. However, since 100% of the condensate is not returned, whatever solids had been in that water before it evaporated to form steam are left in the remaining water. Fresh feedwater is added to maintain levels, but even fresh water contains some dissolved solids. So over time, the water in the boiler system gets saturated with all sorts of dissolved minerals.
Most realize that damage due to corrosion of metals is costly - but what specifically is that cost and what is included in the total? A study completed in 2002 sponsored by the Federal Highway Administration (FHWA), the National Association of Corrosion Engineers (NACE International) and implemented by CC Technologies Laboratories (now part of DVN) addressed those questions.
Material selection entails picking an engineering material - either metal alloy or non-metal - that is inherently resistant to the particular corrosive environment and also meets other criteria. Variables that will affect corrosion are established along with materials that may provide suitable resistance for those conditions. Obviously other requirements such as cost and mechanical properties of the potential materials must be considered.
An ominous cloud of smoke continues to billow as the sprinklers rain water throughout the facility. The production manager's mechanical and electrical equipment is rapidly deteriorating, and within hours, the previously pristine equipment normally used to manufacture precision circuit boards will have a thin coating of flash rust with further damage forthcoming.
Suppose that you lose your pen. As a result you cannot write because you do not have a writing instrument that functions. That simple device, your pen, has a miraculous effect on your ability to perform. It is in this connection that we want to discuss the science and technology of corrosion