U.S. Power Boiler and Heat Exchanger Manufacturing (NAICS 33241): An Investor Primer

This is a short rollup page. NAICS industry 33241 is effectively identical to its single child industry, 332410. For the full company-by-company treatment, demand analysis and detailed sourcing, read the 332410 primer.

1. Overview

North American Industry Classification System (NAICS) code 33241 covers U.S. factories that manufacture power boilers and heat exchangers.[1] A power boiler converts heat into high-pressure steam; a heat exchanger transfers heat between fluids without necessarily mixing them. These are engineered, safety-critical products used in power generation, nuclear plants, liquefied natural gas (LNG), refining, chemicals, defense, data centers and other industrial processes.

Because this level has exactly one child (see Section 2), everything true of 332410 is true of 33241. The industry pairs attractive features—qualification barriers, large installed bases and recurring replacement work—with hard project economics, where fixed-price contracts and volatile metal costs can turn revenue growth into losses.

2. What's Inside — Why This Level Equals Its One Child

NAICS is hierarchical. A five-digit "industry" such as 33241 can be split into several six-digit "national industries," but here it is not: 33241 contains a single child, 332410 — Power Boiler and Heat Exchanger Manufacturing, which carries the identical title and definition.[1] When an industry is not subdivided further, the U.S. five-digit and six-digit levels are coextensive—one is a pass-through for the other.

The practical consequence: the establishments, companies, products, economics and competitive dynamics of 33241 are exactly those of 332410. This page reports this level's own federal figures and summarizes the key points; the 332410 primer carries the full detail.

The classification includes manufacturers that also install their own equipment. It excludes heavy-gauge metal tanks (NAICS 332420), low-pressure heating boilers (NAICS 333414) and install-only contractors (NAICS 238220).[1] Those exclusions matter more than they look. "Power boiler" is easily misread as "coal-power equipment," when the category also spans industrial and marine steam generation and a heat-exchanger side serving refining, chemicals, food, pulp and paper, LNG, nuclear, defense and data centers. And because Census deliberately carves out tanks, low-pressure heating boilers and installation work, commercial reports labeled "boiler market," "HVAC heat exchangers" or "pressure vessels" routinely overstate the addressable market at this code.[1] NAICS is also assigned per establishment, not per company, so a diversified corporation can have a plant here while most of its revenue sits elsewhere.

3. Size (This Level's Federal Figures)

Two federal sources describe this level. The U.S. Census Bureau's County Business Patterns (CBP) counts employer establishments and jobs; the 2022 Economic Census reports sales and market structure. Because they cover different years, the figures below should be read as complementary, not as a single snapshot.

With 185 firms operating 237 establishments, some companies run more than one plant. Sales of about $7.1 billion across roughly 237 establishments imply an average of roughly $30 million per plant—a rough, cross-year approximation, not a precise figure.

A divergence readers should know about. The two levels do not currently carry the same statistics. The revised 332410 primer reports the CBP establishment, employment and payroll figures above, but it does not carry sales, firm count or a concentration index: its research pass could not reach the Economic Census table and it declined to estimate rather than fill the gap. The sales, firm-count and concentration figures on this page therefore come from this level's own Economic Census source and are not corroborated by the child page; the child instead falls back on older historical evidence of fragmentation (see Section 8). Treat the 2022 sales and firm counts as this page's figures.

Undercount caveat. County Business Patterns covers employer establishments and can miss nonemployer businesses, government production and fabrication performed inside plants classified under a different primary activity.[2] That matters most for vertically integrated naval and defense production. Because this is a capital-intensive industry rather than one dominated by tiny individual-owner shops, the undercount is smaller here than in many service industries—but it is not zero. No suppressed value is stated anywhere in this page.

4. Investable Universe

Value in this industry is spread across a mix of public companies, private-equity platforms and family businesses; both the current and the historical federal evidence point to a fragmented structure (see Section 8). There is no clean industry exchange-traded fund (ETF) and few public pure plays; public investors reach the industry mainly through diversified equipment companies. Because 33241 and 332410 are the same population, the investable set is identical to the child's.

The defining feature of that set is how far apart its members sit in scale and purity. Babcock & Wilcox Enterprises (NYSE: BW) is the most direct listed exposure but also the smallest, with 2025 revenue of $587.7 million and backlog of $423.6 million—of which parts were about 41% of revenue, split $241.6 million parts, $186.9 million projects and $159.2 million construction.[4] Graham Corporation (NYSE: GHM) has direct product exposure that is drifting away from this industry's traditional end markets: fiscal 2026 sales were $245.3 million, 82% recognized over time, with 85% of backlog defense-related and two customers each above 10% of revenue.[5] BWX Technologies (NYSE: BWXT) reaches the highest-barrier niche—it describes itself as the only commercial heavy nuclear-component manufacturer in North America—but its Commercial Operations segment was $853.1 million of $3.198 billion in 2025 consolidated revenue, and the heat-exchanger share within that is undisclosed.[6] Baker Hughes (NASDAQ: BKR) completed its acquisition of Chart Industries in July 2026; Chart generated $4.3 billion of revenue in 2025, and its Heat Transfer Systems segment alone booked $1.468 billion of orders on $1.035 billion of 2024 sales, closing with $2.097 billion of backlog, growth management attributed to LNG and data centers.[7][8] Modine Manufacturing (NYSE: MOD) is the most adjacent, with fiscal 2026 Climate Solutions sales of $2.062 billion.[9]

Read together, the list spans a near-pure play smaller than a tenth of this level's reported sales up to segments of multibillion-dollar diversified groups—and none of them discloses U.S. 332410 output. No listed name is a precise proxy for this industry. International exposure runs through Alfa Laval and through Miura, now the owner of Cleaver-Brooks, at the cost of added currency and accounting considerations. Major private or strategically owned operators include Cleaver-Brooks, Kelvion, Babcock Power, Fulton, Metalforms Heat Transfer and API Heat Transfer, alongside numerous regional code shops. The 332410 primer has the full table with revenue, backlog and purity notes.

5. How the Money Works

Most large products are engineered to order, so revenue tracks customer capital spending, contract awards and backlog conversion rather than high-volume throughput. Three economic models coexist: projects (large boilers and exchangers—big revenue, real execution risk), standard equipment (smaller repeatable products) and aftermarket (replacement tubes, parts, inspections and upgrades—steadier demand and better cash conversion). B&W's parts revenue, at roughly 41% of its 2025 total, shows how much of a qualified manufacturer's business the installed base can carry.[4] Large contracts typically use percentage-of-completion accounting, so a revised cost estimate can recognize a project loss immediately; customer advances and milestone payments ease working capital, while retainage, delayed approvals and inventory builds consume it.[4][5]

Carbon steel, stainless steel, nickel alloys, tubes, forgings and skilled welding labor are the main input costs, and the current price setup is exactly the one that hurts fixed-price backlog: this industry's output Producer Price Index rose 15.1% year over year in June 2026, while the steel-mill-products index rose 16.9%—inputs running ahead of output pricing.[10][11] Execution shows through quickly. Graham's fiscal 2026 gross profit was $57.8 million, or 23.5% of sales, with margin down on a heavier mix of lower-margin defense material receipts, roughly $1.0 million of incremental tariff cost and the non-recurrence of a training grant.[5] Beyond headline industry growth, profitability turns on product mix, factory absorption, contract execution and aftermarket content. The child primer details the key operating indicators (orders, book-to-bill, backlog quality and margin, aftermarket share, welder availability, contract assets, project-loss provisions).

6. Demand Drivers

Demand comes from electricity and data-center load growth—the U.S. Department of Energy estimated data centers used 4.4% of U.S. electricity in 2023, with a projected 6.7%–12% by 2028[12]—plus power-generation construction, LNG export projects, nuclear work and routine industrial replacement during scheduled outages. The drivers do not translate into orders evenly, which is the point worth carrying up to this level. Developers planned 86 gigawatts of U.S. generating-capacity additions for 2026, but only 6.3 gigawatts of that is natural gas and 3.3 gigawatts combined-cycle;[13] solar and battery additions, which dominate the total, use little steam equipment. LNG is the more mechanically direct pull: North American export capacity was forecast to rise from 11.4 billion cubic feet per day in 2023 to 24.4 billion by 2028, which requires cryogenic exchangers, condensers and process equipment.[14] Nuclear supports the highest-specification components through life extensions, naval procurement and possible new build, with federal policy targets of 35 gigawatts of added capacity by 2035 and 200 gigawatts by 2050—goals, not demand forecasts.[15] Installed-base replacement remains steadier than new-plant construction, and while coal retirements cut legacy boiler demand, heat exchangers are far less exposed because heat pumps, hydrogen, carbon capture, LNG, nuclear and waste-heat recovery all need thermal-management equipment. See the 332410 primer for the full driver-by-driver detail and figures.

7. Regulation

The American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (BPVC) is the central qualification framework—Section I (power boilers), Section VIII (pressure vessels) and Section III (nuclear components).[16] Certification, approved welding procedures, material traceability and nondestructive examination create both cost and competitive barriers, and the National Board Inspection Code, adopted in most U.S. and Canadian jurisdictions, governs installation, inspection and repair after the unit ships.[17] Nuclear suppliers additionally face Nuclear Regulatory Commission (NRC) quality-assurance requirements; customers' emissions decisions fall under Environmental Protection Agency (EPA) Boiler rules; plants operate under Occupational Safety and Health Administration (OSHA) hot-work standards; and Section 232 metal tariffs can move input costs. The child primer covers each in full.

8. Consolidation

The federal market-structure data at this level describe a fragmented, unconcentrated industry.[3] The four largest firms hold 33.9% of sales (a measure called the four-firm concentration ratio, CR4); the top eight hold 44.4%, the top 20 hold 63.9% and the top 50 hold 84.1%. The Herfindahl-Hirschman Index (HHI)—the sum of each firm's squared market share, where higher means more concentrated—is just 482, well below the 1,500 mark U.S. antitrust agencies treat as the floor of "moderately concentrated."

As noted in Section 3, the child primer does not carry these figures. Unable to reach a current concentration table, it cites instead a Small Business Administration analysis of the 2012 Economic Census putting CR4 at 27.3%, and warns that the ratio is too old to describe present-day concentration confidently.[18] The two readings differ in vintage and in level—33.9% versus 27.3%—but not in direction: on either measure no single company dominates nationally. The more important qualification is common to both. National fragmentation coexists with high concentration in individual niches: nuclear steam generators, naval propulsion equipment, utility-scale condensers, LNG brazed-aluminum exchangers and standardized package boilers demand different facilities and qualifications, so a manufacturer can hold real pricing power in a qualified niche while looking invisible in industry-level data.

Strategic and sponsor interest is active. Miura bought Cleaver-Brooks in May 2024;[19] Apollo-managed funds completed their acquisition of a majority interest in Kelvion in January 2026, with Triton retaining a minority stake;[20][21] Baker Hughes closed the Chart Industries acquisition in July 2026;[7] and Metalforms Heat Transfer, part of TransTech Group under Bridge Industries, acquired Koch Heat Transfer's North American business in September 2024.[22] Consolidation expands aftermarket reach and product breadth but does not remove local fabrication capacity or customer qualification requirements.

9. Risks

• Fixed-price overruns: steel, labor, engineering or installation costs exceeding estimates.
• Project timing: permitting, financing and approvals can delay or cancel orders.
• Quality failures: weld defects or pressure failures can cause recalls, litigation and reputational damage.
• Customer concentration and cyclicality: power, LNG, refining and chemical capital spending arrives in waves, and a few utilities, contractors or government programs can drive a supplier's results—Graham reported two customers each above 10% of revenue, with 85% of backlog defense-related.[5]
• Energy transition: coal retirements cut legacy boiler demand and electrified process heating can displace some fuel-fired boilers; heat-exchanger exposure is materially lower.
• Labor scarcity: pressure-boundary welding, nondestructive examination and nuclear-quality personnel are not interchangeable with general fabrication labor.
• Trade exposure and working capital: tariffs and imports affect price, but delayed forgings, castings or qualified tubing can stall an entire project and trigger liquidated damages; retainage, inventory and contract assets consume cash despite reported profit.
• Technology and overbuild: data-center, hydrogen, carbon-capture and advanced-reactor expectations may not convert into economic projects.

10. How to Invest and Outlook

Public investors typically treat BW as the most direct listed exposure while weighing its balance-sheet and execution risk, use GHM and BWXT for higher-barrier defense and nuclear exposure, and use BKR and MOD for diversified cryogenic, industrial and data-center thermal participation. Useful comparisons include organic orders, book-to-bill, backlog margin, free cash flow, net debt and enterprise value to earnings before interest, taxes, depreciation and amortization (EBITDA). Private investors have a broader field of specialist fabricators, service companies and regional platforms; diligence should normalize EBITDA for project adjustments, test backlog margins job by job, examine customer advances and bonding capacity, and separate recurring aftermarket earnings from volatile new-build revenue. The central underwriting mistake at either level is to apply a global "heat exchanger market" growth rate or an HVAC boiler multiple to a company in this code—the classification's exclusions make those markets a different population.

Outlook—editorial judgment: the demand setup is constructive but uneven. Electricity growth, data centers, LNG, nuclear refurbishment and industrial efficiency should support orders and aftermarket work, but metal inflation, tariffs, scarce skilled labor and fixed-price execution can absorb that growth—margin expansion is the less certain half of the story. The most attractive businesses are likely to be qualified niche leaders with recurring service revenue, disciplined contract terms and limited balance-sheet dependence. For the complete analysis, read the 332410 primer.

Sources

1. U.S. Census Bureau, 2022 North American Industry Classification System Manual, 2022, https://www.census.gov/naics/reference_files_tools/2022_NAICS_Manual.pdf
2. U.S. Census Bureau, 2023 County Business Patterns: Table CB2300CBP, 2025, https://data.census.gov/table/CBP2023.CB2300CBP
3. U.S. Census Bureau, 2022 Economic Census: Concentration by Largest Firms (NAICS 33241), 2025, https://www.census.gov/programs-surveys/economic-census.html
4. Babcock & Wilcox Enterprises, Annual Report on Form 10-K for 2025, 2026, https://www.sec.gov/Archives/edgar/data/1630805/000163080526000018/bw-20251231.htm
5. Graham Corporation, Annual Report on Form 10-K for Fiscal 2026, 2026, https://www.sec.gov/Archives/edgar/data/716314/000119312526260688/ghm-20260331.htm
6. BWX Technologies, Annual Report on Form 10-K for 2025, 2026, https://www.sec.gov/Archives/edgar/data/1486957/000148695726000007/bwxt-20251231.htm
7. Baker Hughes, Baker Hughes Completes Acquisition of Chart Industries, 2026, https://investors.bakerhughes.com/news/press-releases/news-details/2026/Baker-Hughes-Completes-Acquisition-of-Chart-Industries/default.aspx
8. Chart Industries, Annual Report on Form 10-K for 2024, 2025, https://www.sec.gov/Archives/edgar/data/892553/000089255325000039/gtls-20241231.htm
9. Modine Manufacturing, Annual Report on Form 10-K for Fiscal 2026, 2026, https://www.sec.gov/Archives/edgar/data/67347/000110465926066795/mod-20260331x10k.htm
10. Federal Reserve Bank of St. Louis, Producer Price Index: Power Boiler and Heat Exchanger Manufacturing, 2026, https://fred.stlouisfed.org/data/PCU332410332410
11. U.S. Bureau of Labor Statistics, Producer Price Index—Metals and Metal Products, 2026, https://www.bls.gov/regions/mid-atlantic/data/producerpriceindexmetals_us_table.htm
12. U.S. Department of Energy, DOE Releases New Report Evaluating Increase in Electricity Demand from Data Centers, 2024, https://www.energy.gov/articles/doe-releases-new-report-evaluating-increase-electricity-demand-data-centers
13. U.S. Energy Information Administration, Developers Plan to Add 86 Gigawatts of U.S. Generating Capacity in 2026, 2026, https://www.eia.gov/todayinEnergy/detail.php?id=67205
14. U.S. Energy Information Administration, North American LNG Export Capacity Is on Track to More Than Double by 2028, 2025, https://www.eia.gov/todayinenergy/detail.php?id=64128
15. U.S. Department of Energy, United States Sets Targets to Triple Nuclear Energy Capacity by 2050, 2024, https://www.energy.gov/ne/articles/us-sets-targets-triple-nuclear-energy-capacity-2050
16. American Society of Mechanical Engineers, Boiler and Pressure Vessel Code—2025 Edition, 2025, https://www.asme.org/codes-standards/bpvc-standards/bpvc-2025
17. National Board of Boiler and Pressure Vessel Inspectors, National Board Inspection Code, 2026, https://www.nationalboard.org/PrintPage.aspx?pageID=102
18. U.S. Small Business Administration, Proposed Size Standards Rule, 2022, https://public-inspection.federalregister.gov/2022-08091.pdf
19. Cleaver-Brooks, Miura Purchase of Cleaver-Brooks, 2024, https://cleaverbrooks.com/miura-purchase-of-cleaver-brooks
20. Apollo Global Management, Apollo Funds to Acquire Kelvion, 2025, https://ir.apollo.com/news-events/press-releases/detail/572/apollo-funds-to-acquire-kelvion-a-leading-global-provider
21. Triton Partners, Triton Completes Majority Stake Sale of Kelvion to Apollo Funds, 2026, https://www.triton-partners.com/news/triton-completes-majority-stake-sale-of-kelvion-to-apollo-funds
22. Metalforms Heat Transfer, About Metalforms Heat Transfer, 2024, https://www.metalformsheattransfer.com/about-metalforms-heat-transfer