Environmental Protection Agency Pt. 438, App. B

MISCELLANEOUS METAL PRODUCTS Miscellaneous Fabricated Wire Products Miscellaneous Metal Work Miscellaneous Repair Shops & Related Services Miscellaneous Transportation Equipment

APPENDIX B TO PART 438—OILY (1) Alkaline cleaning is performed to re- OPERATIONS DEFINITIONS move foreign contaminants from parts. This operation usually is done prior to finishing NOTE: The definitions in this appendix (e.g., ). shall not be used to differentiate between the (2) Emulsion cleaning is an alkaline clean- six ‘‘core’’ metal finishing operations (i.e., ing operation that uses either complex Electroplating, Electroless Plating, Anod- chemical enzymes or common organic sol- izing, Coating (chromating, phosphating, and vents (e.g., kerosene, mineral oil, glycols, coloring), Chemical Etching and Milling, and and benzene) dispersed in water with the aid Printed Circuit Board Manufacture) and of an emulsifying agent. The pH of the sol- forty ‘‘ancillary’’ process operations listed at vent usually is between 7 and 9, and, depend- 40 CFR 433.10(a). ing on the solvent used, cleaning is per- Blasting involves removing surface formed at temperatures from room tempera- ° ° film from a part by using abrasive directed ture to 82 C (180 F). This operation often is at high velocity against the part. Abrasive used as a replacement for vapor degreasing. blasting includes bead, grit, shot, and sand Alkaline Treatment Without Cyanide is a blasting, and may be performed either dry or general term used to describe the application with water. The primary applications of wet of an alkaline solution not containing cya- nide to a metal surface to clean the metal abrasive blasting include: Removing burrs on surface or prepare the metal surface for fur- precision parts; producing satin or matte fin- ther . ishes; removing fine tool marks; and remov- Aqueous Degreasing involves cleaning metal ing light mill scale, surface oxide, or welding parts using aqueous-based cleaning chemi- scale. Wet blasting can be used to finish frag- cals primarily to remove residual oils and ile items such as electronic components. greases from the part. Residual oils can be Also, some aluminum parts are wet blasted from previous operations (e.g., machine cool- to achieve a fine-grained matte finish for ants), oil from product use in a dirty envi- decorative purposes. In abrasive blasting, the ronment, or oil coatings used to inhibit cor- water and abrasive typically are reused until rosion. Wastewater generated by this oper- the particle size diminishes due to impacting ation includes spent cleaning solutions and and fracture. rinse waters. Adhesive Bonding involves joining parts Assembly/Disassembly involves fitting to- using an adhesive material. Typically, an or- gether previously manufactured or rebuilt ganic bonding compound is used as the adhe- parts or components into a complete metal sive. This operation usually is dry; however, product or machine or taking a complete aqueous solutions may be used as bonding metal product or machine apart. Assembly/ agents or to contain residual organic bond- disassembly operations are typically dry; ing materials. however, special circumstances can require Alkaline Cleaning for Oil Removal is a gen- water for cooling or buoyancy. Also, rinsing eral term for the application of an alkaline may be necessary under some conditions. cleaning agent to a metal part to remove oil Burnishing involves finish sizing or smooth and grease during the manufacture, mainte- finishing a part (previously machined or nance, or rebuilding of a metal product. This ground) by displacing, rather than removing, unit operation does not include washing of minute surface irregularities with smooth the finished products after routine use (as point or line-contact, fixed or rotating tools. defined in ‘‘Washing (Finished Products)’’ in Lubricants or soap solutions can be used to this appendix), or applying an alkaline cool the tools used in burnishing operations. cleaning agent to remove nonoily contami- Wastewater generated during burnishing in- nants such as dirt and scale (as defined in clude process solutions and rinse water. ‘‘Alkaline Treatment Without Cyanide’’ in Calibration is performed to provide ref- this appendix and ‘‘Alkaline Treatment With erence points for the use of a product. This Cyanide’’ in appendix C of this part). Waste- unit operation typically is dry, although water generated includes spent cleaning so- water may be used in some cases (e.g., pump- lutions and rinse waters. ing water for calibration of a pump). Water

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used in this unit operation usually does not tives. Rinse waters typically are assimilated contain additives. into the working fluid or treated on site. Preventive Coating involves apply- involves modifying the phys- ing removable oily or organic solutions to ical properties of a part by applying con- protect metal surfaces against corrosive en- trolled heating and cooling cycles. This oper- vironments. Corrosion preventive coatings ation includes tempering, carburizing, include, but are not limited to: Petrolatum cyaniding, nitriding, annealing, aging, nor- compounds, oils, hard dry-film compounds, malizing, austenitizing, austempering, solvent-cutback petroleum-based com- siliconizing, martempering, and pounds, emulsions, water-displacing polar malleablizing. Parts are heated in furnaces compounds, and fingerprint removers and or molten salt baths, and then may be cooled neutralizers. Corrosion preventive coating by quenching in aqueous solutions (e.g., does not include electroplating, or chemical brine solutions), neat oils (pure oils with lit- conversion coating operations. Many corro- tle or no impurities), or oil/water emulsions. sion preventive materials also are formu- Heat treating typically is a dry operation, lated to function as lubricants or as a base but is considered a wet operation if aqueous for paint. Typical applications include: As- quenching solutions are used. Wastewater in- sembled machinery or equipment in standby cludes spent quench water and rinse water. storage; finished parts in stock or spare Impact Deformation involves applying im- parts for replacement; tools such as drills, pact force to a part to permanently deform taps, dies, and gauges; and mill products or shape it. Impact deformation may include such as sheet, strip, rod and bar. Wastewater mechanical processes such as hammer forg- generated during corrosion preventive coat- ing, shot peening, peening, coining, high-en- ing includes spent process solutions and ergy-rate , heading, or . rinses. Process solutions are discharged Natural and synthetic oils, light greases, and when they become contaminated with impu- pigmented lubricants are used in impact de- rities or are depleted of constituents. Corro- formation operations. Pigmented lubricants sion preventive coatings typically do not re- quire an associated rinse, but parts are include whiting, lithapone, mica, zinc oxide, sometimes rinsed to remove the coating be- molybdenum disulfide, bentonite, flour, fore further processing. graphite, white lead, and soap-like mate- Electrical Discharge Machining involves re- rials. These operations typically are dry, but moving metals by a rapid spark discharge be- wastewater can be generated from lubricant tween different polarity electrodes, one the discharge and from rinsing operations associ- part and the other the tool, separated by a ated with the operation. small gap. The gap may be filled with air or Iron Phosphate Conversion Coating is the a dielectric fluid. This operation is used pri- process of applying a protective coating on marily to cut tool alloys, hard nonferrous al- the surface of a metal using a bath con- loys, and other hard-to-machine materials. sisting of a phosphoric acid solution con- Most electrical discharge machining proc- taining no metals (e.g., manganese, nickel, esses are operated dry; however, in some or zinc) or a phosphate salt solution (i.e., so- cases, the process uses water and generates dium or potassium salts of phosphoric acid wastewater containing dielectric fluid. solutions) containing no metals (e.g., man- Floor Cleaning (in Process Area) removes ganese, nickel, or zinc) other than sodium or dirt, debris, and process solution spills from potassium. Any metal concentrations in the process area floors. Floors can be cleaned bath are from the substrate. using wet or dry methods, such as Machining involves removing stock from a vacuuming, mopping, dry sweeping, and hose part (as chips) by forcing a cutting tool rinsing. Non-process area floor cleaning in against the part. This includes machining offices and other similar non-process areas is processes such as turning, milling, drilling, not included in this unit operation. boring, tapping, planing, broaching, sawing, Grinding involves removing stock from a shaving, shearing, threading, reaming, shap- part by using abrasive grains held by a rigid ing, slotting, hobbing, and chamfering. Ma- or semirigid binder. Grinding shapes or chining processes use various types of metal- deburrs the part. The grinding tool usually is working fluids, the choice of which depends a disk (the basic shape of grinding wheels), on the type of machining being performed but can also be a cylinder, ring, cup, stick, and the preference of the machine shop. The strip, or belt. The most commonly used abra- fluids can be categorized into four groups: sives are aluminum oxide, silicon carbide, Straight oil (neat oils), synthetic, semi- and diamond. The process may use a grind- synthetic, and water-soluble oil. Machining ing fluid to cool the part and remove debris operations generate wastewater from work- or metal fines. Wastewater generated during ing fluid or rinse water discharge. Metal- grinding includes spent coolants and rinses. working fluids periodically are discarded be- Metal-working fluids become spent for a cause of reduced performance or develop- number of reasons, including increased bio- ment of a rancid odor. After machining, logical activity (i.e., the fluids become ran- parts are sometimes rinsed to remove cool- cid) or decomposition of the coolant addi- ant and metal chips. The coolant reservoir is

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sometimes rinsed, and the rinse water is painting operations. Solvent degreasing op- added to the working fluid. erations typically are not followed by rins- Painting-Spray or Brush (Including Water ing, although rinsing is performed in some Curtains) involves applying an organic coat- cases. ing to a part. Coatings such as paint, var- Steam Cleaning removes residual dirt, oil, nish, lacquer, shellac, and plastics are ap- and grease from parts after processing plied by spraying, brushing, roll coating, though other unit operations. Typically, ad- lithographing, powder coating, and wiping. ditives are not used in this operation; the Water is used in painting operations as a sol- hot steam removes the pollutants. Waste- vent (water-borne formulations) for rinsing, water is generated when the cleaned parts for cleanup, and for water-wash (or curtain) are rinsed. type spray booths. Paint spray booths typi- cally use most of the water in this unit oper- Testing (e.g., hydrostatic, dye penetrant, ul- ation. Spray booths capture overspray (i.e., trasonic, magnetic flux) involves applying paint that misses the product during applica- thermal, electrical, mechanical, hydraulic, tion), and control the introduction of pollut- or other energy to determine the suitability ants into the workplace and environment. or functionality of a part, assembly, or com- Polishing involves removing stock from a plete unit. Testing also may include apply- part using loose or loosely held abrasive ing surface penetrant dyes to detect surface grains carried to the part by a flexible sup- imperfections. Other examples of tests fre- port. Usually, the objective is to achieve a quently performed include electrical testing, desired surface finish or appearance rather performance testing, and ultrasonic testing; then to remove a specified amount of stock. these tests typically are dry but may gen- Buffing is included in this unit operation, erate wastewater under certain cir- and usually is performed using a revolving cumstances. Testing usually is performed to cloth or sisal buffing wheel, which is coated replicate some aspect of the working envi- with a suitable compound. Liquid buffing ronment. Wastewater generated during test- compounds are used extensively for large- ing includes spent process solutions and volume production on semiautomated or rinses. automated buffing equipment. Polishing op- Thermal Cutting involves cutting, slotting, erations typically are dry, although liquid or piercing a part using an oxy-acetylene ox- compounds and associated rinses are used in ygen lance, electric arc cutting tool, or some polishing processes. laser. Thermal cutting typically is a dry Pressure Deformation involves applying process, except for the use of contact cooling force (other than impact force) to perma- waters and rinses. nently deform or shape a part. Pressure de- Tumbling/Barrel Finishing/Mass Finishing/Vi- formation may include rolling, drawing, bratory Finishing involves polishing or bending, embossing, sizing, extruding, deburring a part using a rotating or vibrat- squeezing, spinning, necking, forming, ing container and abrasive media or other crimping or flaring. These operations use natural and synthetic oils, light greases, and polishing materials to achieve a desired sur- pigmented lubricants. Pigmented lubricants face appearance. Parts to be finished are include whiting, lithapone, mica, zinc oxide, placed in a rotating barrel or vibrating unit molybdenum disulfide, bentonite, flour, with an abrasive media (e.g., chips, graphite, white lead, and soap-like mate- pebbles), water, and chemical additives (e.g., rials. Pressure deformation typically is dry, alkaline detergents). As the barrel rotates, but wastewater is sometimes generated from the upper layer of the part slides toward the the discharge of lubricants or from rinsing lower side of the barrel, causing the abrading associated with the process. or polishing. Similar results can be achieved Solvent Degreasing removes oils and grease in a vibrating unit, where the entire con- from the surface of a part using organic sol- tents of the container are in constant mo- vents, including aliphatic petroleum (e.g., tion, or in a centrifugal unit, which com- kerosene, naphtha), aromatics (e.g., benzene, pacts the load of media and parts as the unit toluene), oxygenated hydrocarbons (e.g., spins and generates up to 50 times the force ketones, alcohol, ether), and halogenated hy- of gravity. Spindle finishing is a similar drocarbons (e.g., 1,1,1-trichloroethane, tri- process, where parts to be finished are chloroethylene, methylene chloride). Solvent mounted on fixtures and exposed to a rapidly cleaning takes place in either the liquid or moving abrasive slurry. Wastewater gen- vapor phase. Solvent vapor degreasing nor- erated during barrel finishing includes spent mally is quicker than solvent liquid process solutions and rinses. Following the degreasing. However, ultrasonic vibration is finishing process, the contents of the barrel sometimes used with liquid solvents to de- are unloaded. Process wastewater is either crease the required immersion time of com- discharged continuously during the process, plex shapes. Solvent cleaning often is used as discharged after finishing, or collected and a precleaning operation prior to alkaline reused. The parts are sometimes given a cleaning, as a final cleaning of precision final rinse to remove particles of abrasive parts, or as surface preparation for some media.

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Washing (Finished Products) involves clean- metal surface. Acid cleaning, chemical etch- ing finished metal products after use or stor- ing, and pickling are types of acid treat- age using fresh water or water containing a ment. Chromic acid is used occasionally to mild cleaning solution. This unit operation clean cast iron, , cadmium and applies only to the finished products that do aluminum, and bright dipping of copper and not require maintenance or rebuilding. copper alloys. Also, chromic acid solutions Welding involves joining two or more can be used for the final step in acid cleaning pieces of material by applying heat, pres- phosphate conversion coating systems. sure, or both, with or without filler material, Chemical conversion coatings formulated to produce a metallurgical bond through fu- with chromic acid are defined at ‘‘Chromate sion or recrystallization across the interface. Conversion Coating (or Chromating)’’ in this This includes gas welding, resistance weld- appendix. Wastewater generated during acid ing, arc welding, cold welding, electron beam treatment includes spent solutions and rinse welding, and laser beam welding. Welding waters. Spent solutions typically are batch typically is a dry process, except for the oc- discharged and treated or disposed of off site. casional use of contact cooling waters or Most acid treatment operations are followed rinses. by a water rinse to remove residual acid. Wet Air Pollution Control for Organic Con- Acid Treatment Without Chromium is a gen- stituents involves using water to remove or- eral term used to describe any application of ganic constituents that are entrained in air an acid solution not containing chromium to streams exhausted from process tanks or a metal surface. Acid cleaning, chemical production areas. Most frequently, wet air etching, and pickling are types of acid treat- pollution control devices are used with ment. Wastewater generated during acid cleaning and coating processes. A common treatment includes spent solutions and rinse type of wet air pollution control is the wet waters. Spent solutions typically are batch packed scrubber consisting of a spray cham- discharged and treated or disposed of off site. ber that is filled with packing material. Most acid treatment operations are followed Water is continuously sprayed onto the by a water rinse to remove residual acid. packing and the air stream is pulled through Alcohol Cleaning involves removing dirt the packing by a fan. Pollutants in the air and residue material from a part using alco- stream are absorbed by the water droplets hol. and the air is released to the atmosphere. A single scrubber often serves numerous proc- Alkaline Cleaning Neutralization involves ess tanks. using a dilute acid solution to lower the pH of alkaline cleaning rinse water that remains APPENDIX C TO PART 438—METAL- on the part after alkaline cleaning. Waste- water from this operation is the alkaline BEARING OPERATIONS DEFINITIONS cleaning neutralization rinse water. NOTE: The definitions in this appendix Alkaline Treatment With Cyanide is the shall not be used to differentiate between the cleaning of a metal surface with an alkaline six ‘‘core’’ metal finishing operations (i.e., solution containing cyanide. Wastewater Electroplating, Electroless Plating, Anod- generated during alkaline treatment in- izing, Coating (chromating, phosphating, and cludes spent solutions and rinse waters. Al- coloring), Chemical Etching and Milling, and kaline treatment solutions become contami- Printed Circuit Board Manufacture) and nated from the introduction of soils and dis- forty ‘‘ancillary’’ process operations listed at solution of the base metal. They usually are 40 CFR 433.10(a). treated and disposed of on a batch basis. Al- Abrasive Jet Machining includes removing kaline treatment typically is followed by a stock material from a part by a high-speed water rinse that is discharged to a treatment stream of abrasive particles carried by a liq- system. uid or gas from a nozzle. Abrasive jet ma- Anodizing With Chromium involves pro- chining is used for deburring, drilling, and ducing a protective oxide film on aluminum, cutting thin sections of metal or composite magnesium, or other light metal, usually by material. Unlike abrasive blasting, this proc- passing an electric current through an elec- ess operates at pressures of thousands of trolyte bath in which the metal is immersed. pounds per inch. The liquid streams Anodizing may be followed by a sealant oper- typically are alkaline or emulsified oil solu- ation. Chromic acid anodic coatings have a tions, although water also can be used. relatively thick boundary layer and are more Acid Pickling Neutralization involves using a protective than are sulfuric acid coatings. dilute alkaline solution to raise the pH of For these reasons, chromic acid is sometimes acid pickling rinse water that remains on used when the part cannot be rinsed com- the part after pickling. The wastewater from pletely. These oxide coatings provide corro- this operation is the acid pickling neutral- sion protection, decorative surfaces, a base ization rinse water. for painting and other coating processes, and Acid Treatment With Chromium is a general special electrical and mechanical properties. term used to describe any application of an Wastewaters generated during anodizing in- acid solution containing chromium to a clude spent anodizing solutions, sealants,

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