Plastics ancillary processes

Plastics. Part of the trend to substitute plastic and composite substrates for metals can be attributed to a desire to avoid the process of metallic corrosion and subsequent failure. Relatively little attention has been called to the possible failure modes of plastics under environments considered corrosive to metals. More extensive work should be conducted on the durability and life expectancy of plastic and composite materials under end-use environments. A further consideration is the potential for polymer degradation by the products of metal corrosion in hybrid structures comprising metal and polymer components. Since it is expected that coatings will continue to be used to protect plastic and composite substrates, ancillary programs need to be conducted on the mechanisms by which coatings can protect such substrates. 

Materials of construction for ancillary systems are commonly carbon steel, fiberglass-reinforced plastic (FRP), epoxy-or phenolic-lined, stainless steel, and concrete. Many times waste transfer lines will change from a product contact material (near the process equipment) to carbon steel, stainless steel, or polyethylene (near the ancillary equipment). Vent tines are particularly troublesome and require special attention. Smooth surfaces (noncorrugated) with proper sloping to avoid areas for condensation and debris accumulation are essential to minimize corrosion. Smooth and sloping surfaces are cJso needed to aid in cleaning between campaigns. 

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