Basis material

This blender is rated at. 300 ftVh on batchmixing basis 900 ftVh on continuous-mixing basis. Materials rated at 70-lb/fF bulk density. 

Nowadays, however, zinc-coated steel sheets, either continuously galvanised or electroplated, are often used as a basis material for overcoating with plastic materials or paints. The coatings are usually applied continuously and have a range of uses both externally and internally. Many surface finishes are obtainable, e.g. plain or embossed, and in an extensive range of colours, to suit almost any requirement . 

Pretreatment Standards of the Steel Basis Material Subcategory. 295... 

The coil coating sequence, regardless of basis material or conversion coating process used, consists of three operational steps ... 

The selection of basis material, conversion coating, and paint formulation is an art based upon experience. The variables that are typically involved in the selection are appearance, color, gloss, corrosion resistance, abrasion resistance, process line capability, availability of raw materials, customer preference, and cost. Some basis materials inherently work better with certain conversion coatings, and some conversion coatings work better with certain paint formulations. On the whole, however, the choice of which combination to use on a basis material is limited only by plant and customer preferences.1-4... 

The basic objective of the conversion coating process is to provide a corrosion-resistant film that is integrally bonded chemically and physically to the base metal and that provides a smooth and chemically inert surface for subsequent application of a variety of paint films. The conversion coating processes effectively render the surface of the basis material electrically neutral and immune to galvanic corrosion. Conversion coating on basis material coils does not involve the use of applied electric current to coat the basis material. The coating mechanisms are chemical reactions that occur between solution and basis material.1-4... 

After paint application, all coils are cured in an oven. Curing temperatures depend upon basis material, conversion coating, paint formulation, and line speed. Typical temperatures range from 93°C to a maximum of 454°C. Upon leaving the oven, the coils are quenched with water to induce rapid cooling prior to rewinding. 

The quench is necessary for all basis materials, conversion coatings, and paint formulations. A coil that is rewound when too warm will develop internal and external stresses, causing a possible degradation of the appearance of the paint film and of the forming properties of the coil. The volume of water used in the quench often has the largest flow rate of all of the coil-coating processes. However, the water is often circulated to a cooling tower for heat dissipation and reuse. 

Wastewater generation occurs for each basis material (steel, galvanized and aluminum) and for each functional operation (cleaning, conversion coating, and painting). The wastewater generated by the three functional operations may be handled in one of the following ways ... 

Table 7.20 shows the effluent limitations of the steel basis material subcategory that represents the degree of effluent reduction attainable by the application of the BPT currently available. Table 7.21... 

The Effluent Limitations of the Steel Basis Material Subcategory that Represent the Degree of Effluent Reduction Attainable by the Application of the BPT Currently Available... 

Effluent Limitations and Performance Standards of the Galvanized Basis Material Subcategory... 

The New Source Performance Standards (NSPS) of the Steel Basis Material Subcategory that Establish the Quantity or Quality of Pollutants or Pollutant Properties... 

Table 7.27 lists the new source performance standards of the galvanized basis material subcategory that establish the quantity or quality of pollutants or pollutant properties. Table 7.28 lists the pretreatment standards for existing sources of the galvanized basis material subcategory effluents. Table 7.29 lists the pretreatment standards for new sources of the galvanized basis material subcategory effluents. 

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