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Please note: This summary is provided to help you understand the regulations. Consult the references provided for links to the full text of the regulations.

Metalworking Fluids

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This page covers regulations that apply to releasing metalworking fluid components into the environment, and to storing and disposing of metalworking fluid wastes. See the OSHA information page on metalworking fluids for occupational health and safety regulations.

Who is covered by the regulations?

Facilities, such as maintenance and repair facilities, that carry out machining operations.

What is the purpose of the regulations?

Metalworking fluids are complex mixtures of components that carry away heat and provide lubrication during machining processes. Some of the components that have been used in certain metalworking fluid formulations are toxic, or generate toxic products during use.

The regulations are intended to minimize exposure to toxic components in the fluids during use, and to ensure that waste fluid does not become a potential source of exposure.


Regulations applying to disposal of waste fluids and sludges

Metalworking fluids are often captured and recycled, but eventually components in the fluids will decompose to the point that fluid will require disposal. Water-based fluids released directly into wastewater can overload sewage treatment systems, and can contain components that ordinary treatment systems are not designed to handle. Facilities that discharge wastewater to municipal sewage treatment systems are typically required to pretreat fluids until levels of key parameters (such as chemical oxygen demand and total suspended solids) are below specified limits. These limits are generally set by the local authorities responsible for the operating the sewage treatment plants.

Oil-based fluids, and waste fluids in sludges, cannot be added to wastewater and are generally hauled off site. In some instances, metalworking fluids must be managed as hazardous wastes. This can occur either because of materials present in the fluid as purchased, or because of materials that become mixed with the fluid during the machining process. Regulations for dealing with hazardous wastes are intended to ensure that these materials are accounted for at every step until they are permanently sequestered in a secure facility.

Regulations applying to components of fluids

Biocides may be added to metalworking fluids to retard microbial growth and prevent rancid odors. Fluids that contain biocides are regulated under general federal rules that apply to pesticides.

Machine shops should also be aware that there are regulations restricting the use of particularly toxic components or combinations in metalworking fluids. The regulations apply to components added at the point of use, as well as to those present in the original fluid formulation as purchased. Certain additives that contain nitrogen (including some amides and ethanolamines) are of particular concern, since they can react with other components to form nitrosamines, which are known carcinogens. Several of these additives are explicitly prohibited by federal regulations.

Compliance Options

Two main factors affect the environmental compliance burden associated with metalworking fluids:

  • The more waste fluid gets into a facility's wastewater, the more pretreatment may be required to meet discharge limits.
  • For the fluid that is successfully captured before it gets released with the wastewater, the key consideration is whether or not the waste fluid is classified as a "hazardous waste" according to federal regulations

Facilities are responsible for determining whether or not the wastes from their processes fall under the "hazardous" classification. For the kinds of machining operations and materials typically found at vehicle repair facilities, it is generally possible to avoid generating wastes that are considered hazardous under federal regulations. Avoiding the hazardous classification altogether is the best compliance option, since managing hazardous wastes is expensive and burdensome.

For wastes that are not hazardous, metalworking fluids are regulated under the same rules that apply to used oils. The compliance obligations associated with the used oil regulations are generally less burdensome than those associated with hazardous waste management, but there are several items that must be addressed.

One particularly important advantage to avoiding the hazardous classification results from a tradeoff built into the hazardous waste regulations. One of the main ideas behind the Resource Conservation and Recovery Act (RCRA), the 1976 law that established the framework for hazardous waste regulation, was to make it easy to register as a generator of hazardous waste, and relatively convenient (if expensive) to hand off that waste to facilities that specialize in treating, storing, and disposing of the waste ("treatment, storage, and disposal facilities", or TSDFs). Qualifying as a TSDF was intentionally made difficult, involving stringent regulation, and requiring provisions for financial resources to cover potential liability.

One consequence of the RCRA framework is that some simple steps that the generator could take to reduce the quantity of waste or the hazards it poses are ruled out, because it would constitute "treatment" of the waste, and would require the generator to obtain TSDF status. Some of the more obvious problems caused by this arrangement have been patched over by subsequent rules and "determinations", but drawing the line between what a generator may or may not do remains an unresolved issue in many cases. The bottom line for service and maintenance facilities is that, if your waste is deemed hazardous, you may not be able to carry out even simple fluid recovery and recycling operations without risking a citation from a regulatory agency (local, state, or federal).

The following sections lists best practices and several available resources that will help keep metalworking fluids from becoming regulated hazardous wastes, and provides a summary of treatment and disposal options.

Best Practices

The following considerations may help minimize the quantity of waste metalworking fluids needing disposal:

  • When choosing what fluids to use for a particular application, look at entire lifecycle costs, including fluid lifetime, and treatment and disposal costs.
  • Establish a maintenance schedule that includes checks on fluid chemistry and concentration, contamination levels (including dirt, tramp oils, and biological growth), and odors.
  • When fluid is to be diluted with water, use good quality water. An ion exchange system or reverse osmosis unit may be a worthwhile investment for prolonging fluid life.

Further information, including a detailed discussion of avoiding adverse health effects, can be found in Metalworking Fluids: Safety and Health Best Practices Manual, a publication of the federal Occupational Safety and Health Administration (OSHA).

The rest of this section concerns available options for metalworking fluids that have deteriorated to the point where they require disposal.

One disposal option is to ship waste fluids offsite. This is the simplest option from a day-to-day operational standpoint (fewer processes to run on site), but may be costly, particularly if the wastes have to be handled as hazardous wastes. In addition, using another company to process or dispose of the waste does not relieve the waste generator of liability.

If nonhazardous waste fluids are going to be treated on site prior to release, several processes are available, depending on whether the goal is to minimize the volume of waste that must be treated, or to turn the waste into a form suitable for release.

Volume minimizing processes include:

  • evaporation
  • membrane separation
  • treatment to break oil-water emulsions

Destruction processes include:

  • biological treatment
  • chemical treatment to oxidize or decompose materials
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More Resources

Safety and health information from OSHA, including federal safety and health standards for metalworking fluids

Additional health information and recommendations from the National Institute of Occupational Safety and Health (NIOSH)

Federal standards for managing used oil can be found in the Code of Federal Regulations, Title 40, Part 279.