Rolling Mill and Other Metalworking Machinery Manufacturing (U.S.)

NAICS 2022 code 333519 — an investor's primer

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1. Overview

This industry builds the heavy machinery that shapes metal without cutting it — the mills that squeeze steel and aluminum into sheet, strip, plate, bar, and wire, plus the equipment that draws, coils, flattens, and forms wire and rod. If a steel mill or an aluminum plant is a factory, the companies in NAICS 333519 (the U.S. government's "North American Industry Classification System" code for this activity) are the machine-builders whose equipment sits at the heart of it. They also make the consumable rolls — the massive forged or cast cylinders that do the actual squeezing and wear out over time.[1]

Why an investor cares: this is a small, deeply cyclical capital-equipment business whose fortunes ride on one thing above all — when do steel, aluminum, and wire producers spend money to build, expand, or modernize their plants. When mill capex is booming, order books swell; when it stalls, it can go quiet for years. It is a classic "picks-and-shovels" play on the metals industry rather than on metal prices directly.

Public vs. private ways in. There is essentially no U.S.-listed pure play. The world's dominant mill-builders are foreign and mostly private or foreign-listed (Germany's SMS group, Italy's Danieli, Austria's Andritz, the Mitsubishi-backed Primetals).[2] The closest U.S.-listed exposure is Ampco-Pittsburgh (NYSE: AP), whose largest business makes the forged and cast rolls that rolling mills consume.[3] Most genuine U.S. players in 333519 are small, privately held specialists. For most investors this is a sector you touch indirectly — through the steelmakers it serves, through diversified industrials, or through foreign equipment names — rather than through a domestic pure play.

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2. What it is and how it's structured

In scope. NAICS 333519 covers establishments that primarily make:[1][4]

• Rolling mill machinery and equipment — the stands, rolls, and lines that reduce and flatten hot or cold metal into sheet, strip, plate, bar, and rod.
• Rolling mill rolls — the forged and cast work rolls and back-up rolls that are the mill's wearing parts.
• Wire-drawing and wire-fabricating machinery — machines that pull rod through dies to make wire, plus flattening, shaping, coiling, and winding equipment.
• Other metalworking machinery not elsewhere classified — coil winding and cutting machinery, swaging machines, wire-making and assembly machines.

What it explicitly excludes (and where those activities live instead) — this matters because "metalworking machinery" is a big, splintered family:[1][4]

• Machine tools — the metal-cutting and metal-forming machines (lathes, presses, mills, stamping) — are NAICS 333517, Machine Tool Manufacturing. This is the far larger, better-known sibling.
• Industrial molds — NAICS 333511.
• Special dies, tools, jigs, and fixtures — NAICS 333514.
• Cutting tools and machine-tool accessories — NAICS 333515.
• Welding and soldering equipment — also excluded.

So 333519 is the "everything else" bucket of metalworking-machinery makers: rolling mills and wire equipment are the anchor, and it deliberately leaves out the machine tools and tooling that make up the rest of the NAICS 3335 group.[1] Note that the official definition is establishment-based: a diversified company may have one plant classified here and the rest elsewhere.[4]

Ownership mix. The U.S. side is dominated by privately held, family- and founder-owned specialty machine shops and foundries, plus U.S. subsidiaries and service arms of the big foreign builders. Examples of long-established U.S. private specialists include FENN (Newington, CT, founded 1900), International Rolling Mills (Pawtucket, RI, founded 1978), and Butech Bliss, all niche builders of rolling mills, wire-flattening lines, and wire-drawing machines.[5][6] The one meaningful publicly traded U.S. name with heavy exposure, Ampco-Pittsburgh, reaches the industry mainly through mill rolls rather than whole mills.[3]

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3. How big it is

Federal statistics describe a genuinely small industry:

For perspective, a value of shipments near $3 billion across roughly 280 firms and about 10,000 workers makes this one of the smaller distinct manufacturing industries in the U.S. economy.[7][8] (The 2021 Annual Survey of Manufactures showed $3.58 billion in value of shipments, suggesting year-to-year volatility consistent with the industry's cyclical nature.[10]) Average establishment employment is only around 36 people, and the 500-employee SBA threshold means the large majority of these firms count as small businesses.[9]

Concentration is low. The four largest firms account for just 19.3% of industry revenue, the top eight for 31%, the top twenty for 51.3%, and the top fifty for 75.6%.[8] The Herfindahl-Hirschman Index (HHI, a standard concentration gauge where under 1,500 is "unconcentrated") is only 190.5 — extremely fragmented.[8] In plain terms: no domestic giant dominates; it is a field of many small specialists.

Undercount caveat. These figures capture only firms whose primary U.S. activity is classified here. They understate the true economic footprint of "who builds rolling mills for America," because most of the largest, most advanced mill lines installed at U.S. steel and aluminum plants are engineered and supplied by foreign builders — SMS group, Danieli, Primetals, Andritz — whose sales are booked abroad and do not appear in this U.S. industry code at all.[2] The domestic statistics are best read as measuring the U.S.-based specialty and consumables segment, not the full value of rolling-mill equipment consumed in the country.

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4. The investable universe

There is no clean domestic pure play, so the honest summary is: public exposure to this exact industry is thin and mostly indirect.

Public companies with direct or partial exposure

Major private / other players

• SMS group (Germany) — family-controlled through the Familie Weiss Foundation. In 2024 it reported €4.03 billion of sales, €3.62 billion of order intake, and more than 13,500 employees. Metallurgical plant-engineering order intake fell 37.2% to €2.31 billion because an unusually large prior-year contract did not repeat — evidence of the project lumpiness that defines this industry. One of the two or three dominant global suppliers of rolling mills and metallurgical plant. Not publicly traded.[18]
• Fives Group (France) — private; builds rolling and processing lines, including specialized cold-rolling and processing lines for non-grain-oriented and grain-oriented electrical steel.[2][19]
• U.S. specialists — FENN, International Rolling Mills, Butech Bliss, Casey Equipment, Blue Ridge Metals, Precision Rolls and similar privately held niche builders of wire-drawing, wire-flattening, and precision rolling equipment.[5][6]

Bottom line for allocators: to own "the machines that roll America's steel," the practical routes are a small-cap consumables/roll maker (Ampco-Pittsburgh), a U.S.-listed diversified industrial with partial exposure (Park-Ohio), foreign-listed mill-builders (Danieli, Andritz, MHI), or — more simply — the steel and aluminum producers whose capex is this industry's revenue.

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5. How the money works

This is a long-cycle, engineered-to-order capital-goods business, and owners make money on a different rhythm than a typical manufacturer. The metrics that matter:

• Order intake and backlog. Revenue is lumpy and project-based. A single new mill line or roll contract can be worth millions and take quarters or years to build and install, so the leading indicator of health is bookings and the backlog of signed but undelivered work, not this quarter's shipments.[3][14] Ampco-Pittsburgh, for example, points investors to its roll-order backlog as the read on future revenue.[3]
• Engineering and aftermarket margins. The install of a mill is often lower-margin; the money compounds in the aftermarket — spare parts, service, retrofits, automation upgrades, and above all consumable rolls, which wear out and must be replaced on a recurring cycle. Recurring roll and service revenue is stickier and higher-margin than one-off equipment sales. Park-Ohio illustrates this dynamic: replacement parts and field service supply approximately 49% of the revenue of its induction/melting business.[3][12]
• Surcharge pass-throughs and input costs. Roll and equipment makers are heavy users of scrap, alloy, and energy. Contracts often include surcharge pass-throughs that move selling prices up and down with raw-material cost — which flatters or depresses reported sales without necessarily changing profit. Watch base pricing and operating income, not headline sales: Ampco-Pittsburgh grew Forged & Cast operating income ~38% in 2024 on better pricing and factory absorption even as volume and surcharge sales fell.[3]
• Capacity utilization / absorption. Specialty foundries and forges have high fixed costs. Keeping the furnaces and machining lines full ("absorbing" overhead) is the swing factor between good and bad years.[3]
• Cyclicality is the master variable. Because customers only buy when they are expanding, this industry's revenue amplifies the steel/aluminum capital cycle — great in build-out years, austere in the troughs. Orders can collapse before reported revenue does (backlog provides a lag), while recovery in revenue trails customer capital-spending decisions.

Margin variability. Profitability varies widely by company and project type. Standardized machinery, spare parts, and software generally carry less execution risk than first-of-kind turnkey plants. Public segments provide useful bounds: Andritz's Metals segment reported a 6.7% EBITDA margin in 2025 (with management attributing weaker orders to low investment by automotive and steel producers), while Danieli's Plantmaking achieved a 12.3% EBITDA margin in fiscal 2025.[13][15] Ampco-Pittsburgh's roll segment posted a 3.7% operating margin in 2024.[11] A single "industry margin" would obscure these differences.

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6. What drives demand

Demand is derived almost entirely from customers' willingness to invest in metal-producing and metal-processing capacity:

• Steel and aluminum mill capex. The dominant driver. The U.S. is in an unusual build-out: electric-arc-furnace (EAF) steelmaking — the recycling-based "mini-mill" route — reached about 69% of U.S. output in 2024, up from 14% in 1969, and new EAF and finishing capacity keeps coming online.[20] Nucor alone committed roughly $3–4 billion of capex across 2024–2026 on new sheet, rebar, and value-added lines.[20] Every new melt shop needs rolling and finishing equipment, rolls, and service.
• Trade policy pulling investment onshore. The 50% Section 232 steel and aluminum tariffs (see §7) have coincided with more than $10 billion in announced new U.S. mill investment — directly feeding equipment and roll demand.[21]
• Steel demand outlook. The World Steel Association projects U.S. steel demand growth of 1.7% in 2026 and 2.0% in 2027, supported by private technology investment and public infrastructure spending. Those forecasts describe customer demand, not machinery revenue directly, but healthy steel demand is a precondition for mill investment.[22]
• End-market mix. Automotive is the single largest end market for metalworking machinery broadly (~39% of 2025 demand), with aerospace and defense the fastest-growing.[23] The shift to electric vehicles and electrical (grid) steel is pushing mills to add specialized cold-rolling and processing lines for advanced high-strength and silicon steels. Fives, for example, markets specialized processing lines for non-grain-oriented and grain-oriented electrical steel used in EV motors, generators, and transformers.[2][19]
• Wire and rod demand. Wire-drawing and forming equipment tracks construction, autos, energy transmission, and cable — a separate but related pull.[1]
• Modernization and automation. Beyond new capacity, mills continually retrofit for efficiency, decarbonization (BF-BOF to EAF conversion), and Industry-4.0 automation — a steadier replacement-and-upgrade stream layered on top of the boom-bust of greenfield builds. Digitalization adds sensors, quality models, remote monitoring, and predictive maintenance, raising recurring software and service content.[20]

As a gauge of the current cycle, cumulative new U.S. orders for metalworking machinery ran about $2.52 billion through the first half of 2025, up 13.7% year over year — a sign producers are committing capital.[23] (Forward-looking industry forecasts putting the global rolling-mill-machine market on a mid-single-digit growth path to the mid-2030s are projections, not guarantees, and depend on exactly this capex cycle holding up.[2])

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7. Regulation

This is a machine-building industry, so it is not price- or license-regulated the way utilities or banks are. The regulatory forces that actually move it are trade, safety, and environment:

• Section 232 tariffs. In June 2025 the U.S. raised tariffs on imported steel and aluminum to 50% (from 25%), and later extended the duties to hundreds of downstream derivative products.[21] For 333519 the effect is two-edged: tariffs raise domestic steelmakers' pricing and have triggered a wave of new U.S. mill investment (good for equipment and roll demand), while also raising the cost of imported machinery and metal inputs the equipment-builders themselves use.[21]
• Import competition and trade remedies. Because the biggest mill lines are imported, tariff and antidumping policy on capital equipment directly shapes the domestic industry's competitive position against SMS, Danieli, and Primetals.[2]
• Workplace and machine safety. OSHA machine-guarding standards govern heavy-industrial production, including general machine guarding, lockout/tagout, electrical safety, mechanical power-transmission guarding, and specific standards for presses and forging machinery.[24] BLS reported a 2022 total-recordable injury rate of 4.2 cases per 100 full-time workers for NAICS 333519 and a days-away/restriction/transfer rate of 2.1 — elevated relative to manufacturing overall.[25]
• Environmental compliance. Machining fluids, painting, welding, heat treatment, oily wastewater, and hazardous-waste handling create environmental exposure. EPA's Metal Products and Machinery effluent rule applies to direct dischargers that manufacture, rebuild, or maintain metal products and machinery and generate oily wastewater.[26]
• Export controls. Advanced metallurgical and specialty-metals equipment can fall under U.S. export-licensing regimes when sold abroad.

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8. Competitive dynamics and consolidation

Two different competitive worlds sit inside this code:

The domestic specialty market is fragmented and stable. With a CR4 of 19.3% and an HHI of ~190, no U.S. firm dominates; the field is many small, differentiated builders competing on engineering, precision, and service in narrow niches (specialty wire, precision flat-rolling, particular roll grades).[8] Barriers are the metallurgical know-how, installed base, and customer relationships rather than sheer scale.

The global mill-building market is an oligopoly. At the top end — full hot/cold rolling lines and complete metals plants — a handful of large players (SMS group, Danieli, Primetals, Andritz, Fives) command the market and compete on technology, financing, and lifecycle service.[2] North American supply for large projects is described as consolidating around Danieli, SMS, and Primetals.[2] U.S. firms mostly do not compete head-to-head for these mega-projects; they win the specialty niches, the rolls, and the aftermarket.

The project-based nature creates inherent volatility: SMS group's 37.2% decline in metallurgical plant-engineering order intake in 2024 (from €3.68 billion to €2.31 billion) resulted simply from a large prior-year contract not repeating — not from any structural market shift.[18]

Consolidation in the U.S. tends to come through the roll/foundry side (Ampco-Pittsburgh's combination of Union Electric Steel and the acquired Åkers roll business is the notable example) rather than through mill-builder mergers.[3]

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9. Risks

• Deep cyclicality. Revenue is tied to lumpy customer capex; a pause in mill investment can dry up orders for years. This is the defining risk.
• Concentrated, project-based revenue. A few large contracts can dominate a year; a slipped or cancelled project hits hard, and long lead times mean today's backlog reflects decisions made quarters ago.[3][14]
• Import competition. The most advanced, largest-scale equipment is supplied by well-capitalized foreign builders; domestic firms are squeezed at the high end and depend on niches and service.[2]
• Raw-material and energy cost swings. Scrap, alloy, and energy are major inputs; surcharge mechanisms help but do not fully insulate margins. Park-Ohio warns that steel and component suppliers can raise prices quickly, while customer price increases may be delayed or unavailable.[3][12]
• Trade-policy whiplash. The same tariffs that spur U.S. mill investment can reverse, and they raise the cost of imported components — policy is a swing factor in both directions. Park-Ohio identifies tariffs on steel, aluminum, and imported components as a direct cost exposure.[12][21]
• Specialized labor scarcity. Mechanical, electrical, and controls engineers; machinists; welders; field installers; and commissioning personnel are not readily interchangeable. Park-Ohio reports that a declining skilled-labor applicant pool has caused higher costs, inefficiencies, and downtime. Loss of experienced engineers can impair bidding accuracy and project execution.[12]
• Safety and product-liability exposure. Equipment contains rolls, presses, stored energy, high voltage, and heavy moving assemblies. Elevated injury rates and OSHA compliance create operational and legal risk.[24][25]
• Thin public-market liquidity. The one U.S.-listed pure-ish play is a small cap; investors seeking scale must go to foreign listings or to the customer (steel) side.[3]
• Customer concentration in a consolidating steel industry. A shrinking set of large steelmakers (accelerated by the Nippon Steel–U.S. Steel combination) means fewer, more powerful buyers.[20]
• Substitution risks. Customers can defer greenfield orders by rebuilding equipment, buying used or imported machinery, or installing controls upgrades. Alternative materials, near-net-shape casting, additive manufacturing, and redesigned components can reduce some rolling or forming demand. Conversely, retrofit substitution frequently benefits aftermarket specialists.

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10. How to invest and the outlook

Public routes.

• Closest U.S. pure play: Ampco-Pittsburgh (NYSE: AP) — a small cap levered to rolling-mill rolls and the steel/aluminum capex cycle; understand it is roll consumables plus an unrelated air-handling segment, not a whole-mill builder.[3]
• Partial U.S. exposure: Park-Ohio Holdings (NYSE: PKOH) — diversified industrial with induction systems, forging presses, and forming machines; meaningful aftermarket content.[12]
• Foreign-listed mill-builders: Danieli (Milan), Andritz (Vienna), and Mitsubishi Heavy Industries (Tokyo, parent of Primetals) give exposure to the global top tier, bundled with those companies' other businesses.[2][14][16]
• The customer side: owning the U.S. steel and aluminum producers (the buyers of this equipment) is often the more liquid, better-understood way to express a "U.S. metals build-out" thesis.[20]
• Adjacent, not the same thing: broad machine-tool and metalworking-tool names (e.g., Kennametal) sit in neighboring NAICS codes and are not this industry.[17]

Private routes. This is largely a private-market industry: family-owned specialty machine builders, foundries, and roll makers; roll-up opportunities among niche wire-equipment and precision-rolling shops; and the U.S. service and parts arms of foreign OEMs. For private and strategic investors the value is in metallurgical IP, installed base, and recurring aftermarket revenue. The most important diligence items are backlog quality; cancellation and acceptance clauses; customer deposits; percentage-of-completion estimates; warranty history; aftermarket mix; installed-base ownership; customer and supplier concentration; engineering retention; normalized working capital; bonding or letter-of-credit requirements; and cyclically normalized earnings.[5]

Near-term drivers (forward-looking judgment). The setup is unusually constructive for equipment and roll demand: a historic U.S. mill build-out led by EAF mini-mills, 50% steel/aluminum tariffs pulling investment onshore, and rising demand for advanced automotive, electrical, and defense-grade steels that require new processing lines.[20][21][23] Order intake up double digits in early 2025 supports that read.[23] The offsetting reality is that all of this is capex-cycle dependent: the same forces reverse quickly if steel prices, trade policy, or industrial demand soften, and the domestic industry remains small, fragmented, and out-muscled at the high end by foreign builders. This is a cyclical, specialist, picks-and-shovels exposure — attractive in a build-out, unforgiving in a downturn — and best sized accordingly.

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Sources

1. U.S. Census Bureau, "NAICS 333519 — Rolling Mill and Other Metalworking Machinery Manufacturing (definition and scope)," 2022. https://www.naics.com/naics-code-description/?code=333519
2. Market Research Future / Market Research Intellect / Cognitive Market Research, "Rolling Mill and Other Metalworking Machinery Market" (industry structure and leading global suppliers: SMS group, Danieli, Primetals, Andritz, Fives), 2025. https://www.marketresearchfuture.com/reports/rolling-mill-machine-market-37830
3. Ampco-Pittsburgh Corporation, "NYSE: AP Announces Fourth Quarter and Full Year 2024 Results" (net sales $418.3M; Forged & Cast Engineered Products ~67% of revenue; segment operating income +38%; backlog), Business Wire, 2025. https://www.businesswire.com/news/home/20250312478510/en/Ampco-Pittsburgh-Corporation-NYSE-AP-Announces-Fourth-Quarter-and-Full-Year-2024-Results
4. U.S. Census Bureau, "2022 NAICS — 333519 Definition," 2022. https://www.census.gov/naics/?details=333&input=333&year=2022
5. Metoree / FENN / International Rolling Mills, "U.S. rolling mill and wire-drawing machinery manufacturers," 2026. https://us.metoree.com/categories/4003/; https://www.fenn-torin.com/metal-forming-machines/rolling-mills; https://www.introllingmills.com/en/categories/5283-wire-and-rod-processing-equipment
6. Light Metal Age, "2024 Supplier Directory" (SMS, Primetals, Danieli, ANDRITZ Metals USA, Fives, Butech Bliss listed across hot- and cold-rolling categories), 2024. https://www.lightmetalage.com/wp-content/uploads/2024/12/LMA_DEC_2024_directory.pdf
7. U.S. Census Bureau, County Business Patterns (NAICS 333519: 289 establishments; 10,371 employees; $822.8M annual payroll), 2023 (Histometrics ingested federal statistics).
8. U.S. Census Bureau, Economic Census — Industry Concentration (NAICS 333519: 280 firms; $2,973.7M receipts; CR4 19.3%, CR8 31%, CR20 51.3%, CR50 75.6%; HHI 190.5), 2022 (Histometrics ingested federal statistics).
9. U.S. Small Business Administration, "Table of Small Business Size Standards" (NAICS 333519: 500 employees), 2023 (Histometrics ingested federal statistics).
10. U.S. Department of Energy, Technical Support Document using 2021 Census Annual Survey of Manufactures (NAICS 333519: $3.582B value of shipments), 2021. https://downloads.regulations.gov/EERE-2020-BT-STD-0007-0056/content.pdf
11. Ampco-Pittsburgh Corporation, 2024 Annual Report (mill-roll sales $273.0M; segment operating income $10.5M; backlog $250.5M; derived segment operating margin 3.66%), SEC Filing, 2025. https://www.sec.gov/Archives/edgar/data/0000006176/000095017025047819/2024_annual_report.pdf
12. Park-Ohio Holdings Corp., 2025 Form 10-K (aftermarket ~49% of induction/melting revenue; input cost and tariff risks; skilled labor constraints), SEC Filing, 2026. https://www.sec.gov/Archives/edgar/data/1068148/000106814826000003/pkoh-20251231.htm
13. Danieli & C. Officine Meccaniche S.p.A., FY2024/25 Results (Plantmaking revenue €3.116B; EBITDA €384.1M; operating income €320.9M; derived margins 12.3% and 10.3%), 2025. https://www.danieli.com/en/m157/investors/results-and-financial_164.htm
14. ANDRITZ AG, "ANDRITZ achieves strong order intake and stable profitability in 2025" (Group revenue ~€7.9B; Metals division; record backlog), 2026. https://www.andritz.com/newsroom-en/news/2026-03-05-results-2025-group
15. ANDRITZ AG, FY2025 Earnings Call Presentation (Metals segment revenue €1.694B; EBITDA margin 6.7%; EBITA margin 6.1%; capital equipment 73%, service 27%), 2026. https://www.andritz.com/resource/blob/689394/75712d2d9ed4b14eb34cb2a573a3c287/andritz-fy2025-earnings-call-presentation-data.pdf
16. Primetals Technologies, "Who We Are" (wholly owned by MHI; turnkey plants, lines, upgrades, engineering, metallurgical services), 2026. https://www.primetals.com/en/about-us/who-we-are/
17. Kennametal Inc., "Metalworking Tools" (adjacent cutting-tool business, NAICS 333515), 2026. https://www.kennametal.com/us/en/products/metalworking-tools.html
18. SMS group, 2024 Annual Report (sales €4.033B; order intake €3.620B; 13,500+ employees; metallurgical plant-engineering order intake €2.311B, down 37.2%), 2025. https://live.cdn.cms.sms-group.com/SMS_group_website/DataStorage/02_Downloads/2025/2025_Q2/SMS_group_annual_report_2024_EN.pdf
19. Fives Group, "Silicon Steel Processing Lines" (cold-rolling and processing lines for NGO and GO electrical steel), 2026. https://www.fivesgroup.com/steel/strip-processing/silicon-steel-processing-lines
20. Fastmarkets / S&P Global Commodity Insights, "US flat-rolled EAFs fuel new-capacity tsunami" and "Nucor mill build-out and capex" (EAF ~69% of U.S. output in 2024; Nucor ~$3–4B capex 2024–2026), 2024–2025. https://www.fastmarkets.com/insights/us-flat-rolled-eafs-fuel-new-capacity-tsunami/
21. The White House, "Fact Sheet: President Donald J. Trump Increases Section 232 Tariffs on Steel and Aluminum" (25%→50%, effective June 4, 2025; scope expansion; >$10B new U.S. mill investment), 2025. https://www.whitehouse.gov/fact-sheets/2025/06/fact-sheet-president-donald-j-trump-increases-section-232-tariffs-on-steel-and-aluminum/
22. World Steel Association, "Short Range Outlook April 2026" (U.S. steel demand growth 1.7% in 2026, 2.0% in 2027), 2026. https://worldsteel.org/media/press-releases/2026/worldsteel-short-range-outlook-april-2026/
23. Persistence Market Research / market.us, "U.S. metalworking machinery and machine-tools market" (cumulative new orders ~$2.52B through H1 2025, +13.7% YoY; automotive ~39% of demand; aerospace/defense fastest-growing), 2025. https://www.persistencemarketresearch.com/market-research/metalworking-machine-market.asp; https://market.us/report/united-states-machine-tools-market/
24. OSHA, "Machine Guarding eTool — Standards" (general machine guarding, lockout/tagout, electrical safety, mechanical power-transmission guarding, press and forging standards), 2026. https://www.osha.gov/etools/machine-guarding/standards
25. U.S. Bureau of Labor Statistics, "Table 1: Injury and Illness Rates by Industry, 2022" (NAICS 333519: TRC rate 4.2, DART rate 2.1), 2023. https://www.bls.gov/iif/nonfatal-injuries-and-illnesses-tables/table-1-injury-and-illness-rates-by-industry-2022-national.htm
26. U.S. Environmental Protection Agency, "Metal Products and Machinery Effluent Guidelines" (MP&M rule for direct dischargers generating oily wastewater), 2026. https://www.epa.gov/eg/metal-products-and-machinery-effluent-guidelines