Appendix B to Part 438 - Oily Operations Definitions
40:32.0.1.1.14.3.4.1.17 : Appendix B
Appendix B to Part 438 - Oily Operations Definitions Note:
The definitions in this appendix shall not be used to
differentiate between the six “core” metal finishing operations
(i.e., Electroplating, Electroless Plating, Anodizing,
Coating (chromating, phosphating, and coloring), Chemical Etching
and Milling, and Printed Circuit Board Manufacture) and forty
“ancillary” process operations listed at 40 CFR 433.10(a).
Abrasive Blasting involves removing surface film from a
part by using abrasive directed at high velocity against the part.
Abrasive blasting includes bead, grit, shot, and sand blasting, and
may be performed either dry or with water. The primary applications
of wet abrasive blasting include: Removing burrs on precision
parts; producing satin or matte finishes; removing fine tool marks;
and removing light mill scale, surface oxide, or welding scale. Wet
blasting can be used to finish fragile items such as electronic
components. Also, some aluminum parts are wet blasted to achieve a
fine-grained matte finish for decorative purposes. In abrasive
blasting, the water and abrasive typically are reused until the
particle size diminishes due to impacting and fracture.
Adhesive Bonding involves joining parts using an adhesive
material. Typically, an organic bonding compound is used as the
adhesive. This operation usually is dry; however, aqueous solutions
may be used as bonding agents or to contain residual organic
bonding materials.
Alkaline Cleaning for Oil Removal is a general term for
the application of an alkaline cleaning agent to a metal part to
remove oil and grease during the manufacture, maintenance, or
rebuilding of a metal product. This unit operation does not include
washing of the finished products after routine use (as defined in
“Washing (Finished Products)” in this appendix), or applying an
alkaline cleaning agent to remove nonoily contaminants such as dirt
and scale (as defined in “Alkaline Treatment Without Cyanide” in
this appendix and “Alkaline Treatment With Cyanide” in appendix C
of this part). Wastewater generated includes spent cleaning
solutions and rinse waters.
(1) Alkaline cleaning is performed to remove foreign
contaminants from parts. This operation usually is done prior to
finishing (e.g., electroplating).
(2) Emulsion cleaning is an alkaline cleaning operation that
uses either complex chemical enzymes or common organic solvents
(e.g., kerosene, mineral oil, glycols, and benzene) dispersed in
water with the aid of an emulsifying agent. The pH of the solvent
usually is between 7 and 9, and, depending on the solvent used,
cleaning is performed at temperatures from room temperature to 82
°C (180 °F). This operation often is used as a replacement for
vapor degreasing.
Alkaline Treatment Without Cyanide is a general term used
to describe the application of an alkaline solution not containing
cyanide to a metal surface to clean the metal surface or prepare
the metal surface for further surface finishing.
Aqueous Degreasing involves cleaning metal parts using
aqueous-based cleaning chemicals primarily to remove residual oils
and greases from the part. Residual oils can be from previous
operations (e.g., machine coolants), oil from product use in a
dirty environment, or oil coatings used to inhibit corrosion.
Wastewater generated by this operation includes spent cleaning
solutions and rinse waters.
Assembly/Disassembly involves fitting together previously
manufactured or rebuilt parts or components into a complete metal
product or machine or taking a complete metal product or machine
apart. Assembly/disassembly operations are typically dry; however,
special circumstances can require water for cooling or buoyancy.
Also, rinsing may be necessary under some conditions.
Burnishing involves finish sizing or smooth finishing a
part (previously machined or ground) by displacing, rather than
removing, minute surface irregularities with smooth point or
line-contact, fixed or rotating tools. Lubricants or soap solutions
can be used to cool the tools used in burnishing operations.
Wastewater generated during burnishing include process solutions
and rinse water.
Calibration is performed to provide reference points for
the use of a product. This unit operation typically is dry,
although water may be used in some cases (e.g., pumping water for
calibration of a pump). Water used in this unit operation usually
does not contain additives.
Corrosion Preventive Coating involves applying removable
oily or organic solutions to protect metal surfaces against
corrosive environments. Corrosion preventive coatings include, but
are not limited to: Petrolatum compounds, oils, hard dry-film
compounds, solvent-cutback petroleum-based compounds, emulsions,
water-displacing polar compounds, and fingerprint removers and
neutralizers. Corrosion preventive coating does not include
electroplating, or chemical conversion coating operations. Many
corrosion preventive materials also are formulated to function as
lubricants or as a base for paint. Typical applications include:
Assembled machinery or equipment in standby storage; finished parts
in stock or spare parts for replacement; tools such as drills,
taps, dies, and gauges; and mill products such as sheet, strip, rod
and bar. Wastewater generated during corrosion preventive coating
includes spent process solutions and rinses. Process solutions are
discharged when they become contaminated with impurities or are
depleted of constituents. Corrosion preventive coatings typically
do not require an associated rinse, but parts are sometimes rinsed
to remove the coating before further processing.
Electrical Discharge Machining involves removing metals
by a rapid spark discharge between different polarity electrodes,
one the part and the other the tool, separated by a small gap. The
gap may be filled with air or a dielectric fluid. This operation is
used primarily to cut tool alloys, hard nonferrous alloys, and
other hard-to-machine materials. Most electrical discharge
machining processes are operated dry; however, in some cases, the
process uses water and generates wastewater containing dielectric
fluid.
Floor Cleaning (in Process Area) removes dirt, debris,
and process solution spills from process area floors. Floors can be
cleaned using wet or dry methods, such as vacuuming, mopping, dry
sweeping, and hose rinsing. Non-process area floor cleaning in
offices and other similar non-process areas is not included in this
unit operation.
Grinding involves removing stock from a part by using
abrasive grains held by a rigid or semirigid binder. Grinding
shapes or deburrs the part. The grinding tool usually is a disk
(the basic shape of grinding wheels), but can also be a cylinder,
ring, cup, stick, strip, or belt. The most commonly used abrasives
are aluminum oxide, silicon carbide, and diamond. The process may
use a grinding fluid to cool the part and remove debris or metal
fines. Wastewater generated during grinding includes spent coolants
and rinses. Metal-working fluids become spent for a number of
reasons, including increased biological activity (i.e., the
fluids become rancid) or decomposition of the coolant additives.
Rinse waters typically are assimilated into the working fluid or
treated on site.
Heat Treating involves modifying the physical properties
of a part by applying controlled heating and cooling cycles. This
operation includes tempering, carburizing, cyaniding, nitriding,
annealing, aging, normalizing, austenitizing, austempering,
siliconizing, martempering, and malleablizing. Parts are heated in
furnaces or molten salt baths, and then may be cooled by quenching
in aqueous solutions (e.g., brine solutions), neat oils (pure oils
with little or no impurities), or oil/water emulsions. Heat
treating typically is a dry operation, but is considered a wet
operation if aqueous quenching solutions are used. Wastewater
includes spent quench water and rinse water.
Impact Deformation involves applying impact force to a
part to permanently deform or shape it. Impact deformation may
include mechanical processes such as hammer forging, shot peening,
peening, coining, high-energy-rate forming, heading, or stamping.
Natural and synthetic oils, light greases, and pigmented lubricants
are used in impact deformation operations. Pigmented lubricants
include whiting, lithapone, mica, zinc oxide, molybdenum disulfide,
bentonite, flour, graphite, white lead, and soap-like materials.
These operations typically are dry, but wastewater can be generated
from lubricant discharge and from rinsing operations associated
with the operation.
Iron Phosphate Conversion Coating is the process of
applying a protective coating on the surface of a metal using a
bath consisting of a phosphoric acid solution containing no metals
(e.g., manganese, nickel, or zinc) or a phosphate salt solution
(i.e., sodium or potassium salts of phosphoric acid
solutions) containing no metals (e.g., manganese, nickel, or zinc)
other than sodium or potassium. Any metal concentrations in the
bath are from the substrate.
Machining involves removing stock from a part (as chips)
by forcing a cutting tool against the part. This includes machining
processes such as turning, milling, drilling, boring, tapping,
planing, broaching, sawing, shaving, shearing, threading, reaming,
shaping, slotting, hobbing, and chamfering. Machining processes use
various types of metal-working fluids, the choice of which depends
on the type of machining being performed and the preference of the
machine shop. The fluids can be categorized into four groups:
Straight oil (neat oils), synthetic, semisynthetic, and
water-soluble oil. Machining operations generate wastewater from
working fluid or rinse water discharge. Metal-working fluids
periodically are discarded because of reduced performance or
development of a rancid odor. After machining, parts are sometimes
rinsed to remove coolant and metal chips. The coolant reservoir is
sometimes rinsed, and the rinse water is added to the working
fluid.
Painting-Spray or Brush (Including Water Curtains)
involves applying an organic coating to a part. Coatings such as
paint, varnish, lacquer, shellac, and plastics are applied by
spraying, brushing, roll coating, lithographing, powder coating,
and wiping. Water is used in painting operations as a solvent
(water-borne formulations) for rinsing, for cleanup, and for
water-wash (or curtain) type spray booths. Paint spray booths
typically use most of the water in this unit operation. Spray
booths capture overspray (i.e., paint that misses the
product during application), and control the introduction of
pollutants into the workplace and environment.
Polishing involves removing stock from a part using loose
or loosely held abrasive grains carried to the part by a flexible
support. Usually, the objective is to achieve a desired surface
finish or appearance rather then to remove a specified amount of
stock. Buffing is included in this unit operation, and usually is
performed using a revolving cloth or sisal buffing wheel, which is
coated with a suitable compound. Liquid buffing compounds are used
extensively for large-volume production on semiautomated or
automated buffing equipment. Polishing operations typically are
dry, although liquid compounds and associated rinses are used in
some polishing processes.
Pressure Deformation involves applying force (other than
impact force) to permanently deform or shape a part. Pressure
deformation may include rolling, drawing, bending, embossing,
sizing, extruding, squeezing, spinning, necking, forming, crimping
or flaring. These operations use natural and synthetic oils, light
greases, and pigmented lubricants. Pigmented lubricants include
whiting, lithapone, mica, zinc oxide, molybdenum disulfide,
bentonite, flour, graphite, white lead, and soap-like materials.
Pressure deformation typically is dry, but wastewater is sometimes
generated from the discharge of lubricants or from rinsing
associated with the process.
Solvent Degreasing removes oils and grease from the
surface of a part using organic solvents, including aliphatic
petroleum (e.g., kerosene, naphtha), aromatics (e.g., benzene,
toluene), oxygenated hydrocarbons (e.g., ketones, alcohol, ether),
and halogenated hydrocarbons (e.g., 1,1,1-trichloroethane,
trichloroethylene, methylene chloride). Solvent cleaning takes
place in either the liquid or vapor phase. Solvent vapor degreasing
normally is quicker than solvent liquid degreasing. However,
ultrasonic vibration is sometimes used with liquid solvents to
decrease the required immersion time of complex shapes. Solvent
cleaning often is used as a precleaning operation prior to alkaline
cleaning, as a final cleaning of precision parts, or as surface
preparation for some painting operations. Solvent degreasing
operations typically are not followed by rinsing, although rinsing
is performed in some cases.
Steam Cleaning removes residual dirt, oil, and grease
from parts after processing though other unit operations.
Typically, additives are not used in this operation; the hot steam
removes the pollutants. Wastewater is generated when the cleaned
parts are rinsed.
Testing (e.g., hydrostatic, dye penetrant, ultrasonic,
magnetic flux) involves applying thermal, electrical,
mechanical, hydraulic, or other energy to determine the suitability
or functionality of a part, assembly, or complete unit. Testing
also may include applying surface penetrant dyes to detect surface
imperfections. Other examples of tests frequently performed include
electrical testing, performance testing, and ultrasonic testing;
these tests typically are dry but may generate wastewater under
certain circumstances. Testing usually is performed to replicate
some aspect of the working environment. Wastewater generated during
testing includes spent process solutions and rinses.
Thermal Cutting involves cutting, slotting, or piercing a
part using an oxy-acetylene oxygen lance, electric arc cutting
tool, or laser. Thermal cutting typically is a dry process, except
for the use of contact cooling waters and rinses.
Tumbling/Barrel Finishing/Mass Finishing/Vibratory
Finishing involves polishing or deburring a part using a
rotating or vibrating container and abrasive media or other
polishing materials to achieve a desired surface appearance. Parts
to be finished are placed in a rotating barrel or vibrating unit
with an abrasive media (e.g., ceramic chips, pebbles), water, and
chemical additives (e.g., alkaline detergents). As the barrel
rotates, the upper layer of the part slides toward the lower side
of the barrel, causing the abrading or polishing. Similar results
can be achieved in a vibrating unit, where the entire contents of
the container are in constant motion, or in a centrifugal unit,
which compacts the load of media and parts as the unit spins and
generates up to 50 times the force of gravity. Spindle finishing is
a similar process, where parts to be finished are mounted on
fixtures and exposed to a rapidly moving abrasive slurry.
Wastewater generated during barrel finishing includes spent process
solutions and rinses. Following the finishing process, the contents
of the barrel are unloaded. Process wastewater is either discharged
continuously during the process, discharged after finishing, or
collected and reused. The parts are sometimes given a final rinse
to remove particles of abrasive media.
Washing (Finished Products) involves cleaning finished
metal products after use or storage using fresh water or water
containing a mild cleaning solution. This unit operation applies
only to the finished products that do not require maintenance or
rebuilding.
Welding involves joining two or more pieces of material
by applying heat, pressure, or both, with or without filler
material, to produce a metallurgical bond through fusion or
recrystallization across the interface. This includes gas welding,
resistance welding, arc welding, cold welding, electron beam
welding, and laser beam welding. Welding typically is a dry
process, except for the occasional use of contact cooling waters or
rinses.
Wet Air Pollution Control for Organic Constituents
involves using water to remove organic constituents that are
entrained in air streams exhausted from process tanks or production
areas. Most frequently, wet air pollution control devices are used
with cleaning and coating processes. A common type of wet air
pollution control is the wet packed scrubber consisting of a spray
chamber that is filled with packing material. Water is continuously
sprayed onto the packing and the air stream is pulled through the
packing by a fan. Pollutants in the air stream are absorbed by the
water droplets and the air is released to the atmosphere. A single
scrubber often serves numerous process tanks.