Title 40 · EPA

Metal Products And Machinery Point Source Category

40 C.F.R. Part 438 · Updated July 1, 2025

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§ 438.1 — General applicability.

(a) As defined more specifically in subpart A, except as provided in paragraphs (b) through (e) of this section, this part applies to process wastewater discharges from oily operations (as defined at § 438.2(f) and appendix B of this part) to surface waters from existing or new industrial facilities (including facilities owned and operated by Federal, State, or local governments) engaged in manufacturing, rebuilding, or maintenance of metal parts, products, or machines for use in the Metal Product & Machinery (MP&M) industrial sectors listed in this section. The MP&M industrial sectors consist of the following:

(b) The regulations in this part do not apply to process wastewaters from metal-bearing operations (as defined at § 438.2(d) and appendix C of this part) or process wastewaters which are subject to the limitations and standards of other effluent limitations guidelines (e.g., Metal Finishing (40 CFR part 433) or Iron and Steel Manufacturing (40 CFR part 420)). The regulations in this part also do not apply to process wastewaters from oily operations (as defined at § 438.2(f) and appendix B of this part) commingled with process wastewaters already covered by other effluent limitations guidelines or with process wastewaters from metal-bearing operations. This provision must be examined for each point source discharge at a given facility.

(c) Wastewater discharges resulting from the washing of cars, aircraft or other vehicles, when performed only for aesthetic or cosmetic purposes, are not subject to this part. Direct discharges resulting from the washing of cars, aircraft or other vehicles, when performed as a preparatory step prior to one or more successive manufacturing, rebuilding, or maintenance operations, are subject to this part.

(d) Wastewater discharges from railroad line maintenance facilities (as defined at § 438.2(h)) are not subject to this part. Wastewater discharges from railroad overhaul or heavy maintenance facilities (as defined at § 438.2(i)) may be covered by subpart A of this part, the Metal Finishing Point Source Category (40 CFR part 433), or by other effluent limitations guidelines, as applicable.

(e) The following wastewater discharges are not subject to this part:

(1) Non-process wastewater as defined at § 438.2(e).

(2) Wastewater discharges introduced into a Publicly Owned Treatment Works (POTW) or a Federally owned and operated Treatment Works Treating Domestic Sewage (TWTDS), as defined at 40 CFR 122.2.

(3) Process wastewater generated by maintenance and repair activities at gasoline service stations, passenger car rental facilities, or utility trailer and recreational vehicle rental facilities.

(4) Wastewater discharges generated from gravure cylinder preparation or metallic platemaking conducted within or for printing and publishing facilities.

(5) Wastewater discharges in or on dry docks and similar structures, such as graving docks, building ways, marine railways, lift barges at shipbuilding facilities (or shipyards), and ships that are afloat.

(6) Wastewater generated by facilities primarily performing drum reconditioning and cleaning to prepare metal drums for resale, reuse, or disposal.

§ 438.2 — General definitions.

As used in this part:

(a) The general definitions and abbreviations at 40 CFR part 401 shall apply.

(b) The regulated parameters are listed with approved methods of analysis in Table 1B at 40 CFR 136.3, and are defined as follows:

(1) O&G (as HEM) means total recoverable oil and grease measured as n-hexane extractable material.

(2) TSS means total suspended solids.

(c) Corrosion preventive coating means the application of 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.

(d) Metal-bearing operations means one or more of the following: abrasive jet machining; acid pickling neutralization; acid treatment with chromium; acid treatment without chromium; alcohol cleaning; alkaline cleaning neutralization; alkaline treatment with cyanide; anodizing with chromium; anodizing without chromium; carbon black deposition; catalyst acid pre-dip; chemical conversion coating without chromium; chemical milling (or chemical machining); chromate conversion coating (or chromating); chromium drag-out destruction; cyanide drag-out destruction; cyaniding rinse; electrochemical machining; electroless catalyst solution; electroless plating; electrolytic cleaning; electroplating with chromium; electroplating with cyanide; electroplating without chromium or cyanide; electropolishing; galvanizing/hot dip coating; hot dip coating; kerfing; laminating; mechanical and vapor plating; metallic fiber cloth manufacturing; metal spraying (including water curtain); painting-immersion (including electrophoretic, “E-coat”); photo imaging; photo image developing; photoresist application; photoresist strip; phosphor deposition; physical vapor deposition; plasma arc machining; plastic wire extrusion; salt bath descaling; shot tower—lead shot manufacturing; soldering; solder flux cleaning; solder fusing; solder masking; sputtering; stripping (paint); stripping (metallic coating); thermal infusion; ultrasonic machining; vacuum impregnation; vacuum plating; water shedder; wet air pollution control; wire galvanizing flux; and numerous sub-operations within those listed in this paragraph. In addition, process wastewater also results from associated rinses that remove materials that the preceding processes deposit on the surface of the workpiece. These metal-bearing operations are defined in appendix C of this part.

(e) Non-process wastewater means sanitary wastewater, non-contact cooling water, water from laundering, and non-contact storm water. Non-process wastewater for this part also includes wastewater discharges from non-industrial sources such as residential housing, schools, churches, recreational parks, shopping centers as well as wastewater discharges from gas stations, utility plants, and hospitals.

(f) Oily operations means one or more of the following: abrasive blasting; adhesive bonding; alkaline cleaning for oil removal; alkaline treatment without cyanide; aqueous degreasing; assembly/disassembly; burnishing; calibration; corrosion preventive coating (as defined in paragraph (c) of this section); electrical discharge machining; floor cleaning (in process area); grinding; heat treating; impact deformation; iron phosphate conversion coating; machining; painting-spray or brush (including water curtains); polishing; pressure deformation; solvent degreasing; steam cleaning; testing (e.g., hydrostatic, dye penetrant, ultrasonic, magnetic flux); thermal cutting; tumbling/barrel finishing/mass finishing/vibratory finishing; washing (finished products); welding; wet air pollution control for organic constituents; and numerous sub-operations within those listed in this paragraph. In addition, process wastewater also results from associated rinses that remove materials that the preceding processes deposit on the surface of the workpiece. These oily operations are defined in appendix B of this part.

(g) Process wastewater means wastewater as defined at 40 CFR parts 122 and 401, and includes wastewater from air pollution control devices.

(h) Railroad line maintenance facilities means facilities specified at § 438.1 that only perform routine cleaning and light maintenance on railroad engines, cars, car-wheel trucks, or similar parts or machines, and discharge wastewater exclusively from oily operations (as defined in paragraph (f) of this section and appendix B of this part). These facilities only perform one or more of the following operations: assembly/disassembly, floor cleaning, maintenance machining (wheel truing), touch-up painting, and washing.

(i) Railroad overhaul or heavy maintenance facilities means facilities engaged in the manufacture, overhaul, or heavy maintenance of railroad engines, cars, car-wheel trucks, or similar parts or machines. These facilities typically perform one or more of the operations in paragraph (h) of this section and one or more of the following operations: abrasive blasting, alkaline cleaning, aqueous degreasing, corrosion preventive coating, electrical discharge machining, grinding, heat treating, impact deformation, painting, plasma arc machining, polishing, pressure deformation, soldering/brazing, stripping (paint), testing, thermal cutting, and welding.

§ 438.10 — Applicability.

(a) This subpart applies to process wastewater directly discharged from facilities specified at § 438.1.

(b) This subpart applies to process wastewater discharges from oily operations (as defined at § 438.2(f) and appendix B of this part).

(c) This subpart does not apply to process wastewater discharges from metal-bearing operations (as defined at § 438.2(d) and appendix C of this part).

§ 438.12 — Effluent limitations attainable by the application of the best practicable control technology currently available (BPT).

Except as provided at 40 CFR 125.30 through 125.32, any existing point source subject to this subpart must achieve the following effluent limitations representing the application of BPT. Discharges must remain within the pH range 6 to 9 and must not exceed the following:

§ 438.13 — Effluent limitations attainable by application of the best control technology for conventional pollutants (BCT).

Except as provided at 40 CFR 125.30 through 125.32, any existing point source subject to this subpart must achieve the following effluent limitation representing the application of BCT: Limitations for TSS, O&G (as HEM) and pH are the same as the corresponding limitation specified at § 438.12.

§ 438.15 — New source performance standards (NSPS).

New point sources subject to this subpart must achieve the new source performance standards (NSPS) for TSS, O&G (as HEM), and pH, which are the same as the corresponding limitation specified at § 438.12. The performance standards apply with respect to each new point source that commences discharge after June 12, 2003.