for cleaning, intermediate rust protection, and lubrication. Since the focus of this
article is on secondary or indirect chemicals that are used in process operations, but
do not become part of final products, consideration of chemicals for surface treatment
and paints is omitted. In addition to being costly, the process fluids and chemicals
have adverse health and environmental effects, e.g. they contribute to air and water
emissions and generation of hazardous waste (Simpson et al. 2003).