Comments close Thursday on 14 new Section 232 derivative categories that would pull tubas, floor safes and propane cylinders into the metals tariff net, and the inclusions machine shows no sign of slowing
WASHINGTON, Aug. 22, 2026
American importers have until Thursday to tell the Commerce Department why brass-wind musical instruments, floor safes and filled propane cylinders should not be treated as steel, aluminium and copper products for tariff purposes.
The comment period on the Bureau of Industry and Security’s latest Section 232 derivative inclusions proposal closes on August 27. The notice, released on August 4 and published in the Federal Register on August 6, proposes adding 14 categories of downstream goods to the scope of the national security tariffs on aluminium, steel and copper. Most would carry a 25 percent duty on their metal content. Several would carry the different rates prescribed in Proclamation 11032.
The list is a good illustration of how far the metals tariffs have travelled from the mill products they originally covered. It includes aluminium powder, certain brass-wind musical instruments and their parts, welding machine parts, floor safes, certain electric conductor cables, fire extinguishers, heat exchanger parts, hydraulic engine and motor parts, specified cranes and lifting equipment, certain trailers and semi-trailers, and filled steel containers holding propane, oxygen or propylene.
For the sub-set of goods addressed in Proclamation 11032, the applicable rates diverge from the 25 percent baseline. Those items include mobile lifting frames on tyres and straddle carriers, other self-propelled cranes and mobile lifting frames, self-loading and self-unloading trailers and semi-trailers for agricultural use, and the filled steel containers.
Twenty-one days is not a long comment window for a proposal that would change the duty treatment of an orchestra’s tubas and a rancher’s propane bottles in the same document. Importers who have not yet filed have four business days.
How the inclusions process works
The mechanism producing these expansions is worth understanding, because it is now the single most active source of new American tariff liability and it operates almost entirely outside the presidential announcements that generate headlines.
Commerce adopted formal procedures for the Section 232 steel and aluminium tariff inclusions process in a Federal Register notice in August 2025. The process allows domestic producers, industry associations and other interested parties to petition for downstream products to be brought within the scope of the metals tariffs on the theory that imports of the finished article displace domestic demand for the metal it contains. Petitions are filed in defined windows, Commerce evaluates them, and successful petitions result in new derivative product categories added to the Harmonized Tariff Schedule with duties applied to the metal content of the imported article.
The scale of the resulting expansion has been substantial. Commerce has added 407 product categories to the steel and aluminium tariffs through this process, according to the Bureau of Industry and Security, a figure that dwarfs the original 2018 scope. Copper was folded into the same architecture during 2026. Two proclamations this year, in April under the title Strengthening Actions Taken To Adjust Imports of Aluminum, Steel, and Copper Into the United States, and in June under Further Adjusting the Tariff Regimes for Imports of Aluminum, Steel, and Copper Into the United States, restructured rates and administrative mechanics across the whole programme.
The critical design feature, and the one that generates the most compliance friction, is the metal content basis. The Section 232 duty applies to the value of the steel, aluminium or copper content of the imported article, not to the article’s full customs value. The non-metal content is dutiable at whatever rate otherwise applies, including any Section 301, Section 201 or most-favoured-nation rate. An importer of a fire extinguisher must therefore declare, and be able to substantiate, what portion of the entered value represents steel.
For firms that have never had to think about their bill of materials in customs terms, that requirement is a genuine operational burden. It requires supplier cooperation, because the metal content figure has to come from the manufacturer. It requires records that survive audit, because CBP will test the declared split. And it requires a fallback position, because where an importer cannot substantiate the metal content, the practical result is that the duty applies to the full value of the article.
Why these 14 categories
The proposed additions look eccentric read as a list, but each has a domestic petitioner and a displacement theory behind it.
Aluminium powder is an input to metal additive manufacturing, pyrotechnics and paints, and it sits close enough to primary aluminium that its exclusion had been an anomaly. Welding machine parts, heat exchanger parts and hydraulic engine and motor parts are all metal-intensive components where American producers have argued that imported subassemblies substitute directly for domestic steel and aluminium fabrication. Electric conductor cables are a copper displacement case and a straightforward one.
Floor safes and fire extinguishers are consumer and commercial products whose value is overwhelmingly the steel shell. Filled steel containers holding propane, oxygen or propylene present the most interesting question, because the imported article combines a steel pressure vessel with a commodity gas, and the metal content calculation therefore has to separate the cylinder from its contents. Importers of filled cylinders should expect a valuation dispute at some point regardless of how carefully they file.
The brass-wind musical instruments line has attracted the most attention outside trade circles, and not only for novelty. Brass instruments are copper alloy products, and the manufacturing base for professional-grade trumpets, trombones, euphoniums and tubas sits largely in Germany, Japan, China and Taiwan. American school music programmes, university ensembles and orchestras are price-sensitive institutional buyers with fixed budgets. A 25 percent duty on the copper content of a $12,000 professional tuba is a meaningful number for a music department, and the domestic production base is not large enough to absorb the displaced demand at any price.
Specified cranes, lifting equipment and agricultural trailers matter more in dollar terms. Mobile cranes, straddle carriers and self-propelled lifting frames are capital goods for construction, ports and logistics, purchased in small numbers at high unit values. Bringing them into the metals scope at the Proclamation 11032 rates raises the cost of port equipment and construction plant at a moment when both sectors are already absorbing higher costs from the broader tariff programme. Agricultural trailer duties land on farm operators who are simultaneously navigating retaliatory measures against American agricultural exports.
The stacking problem
The single most important thing for an importer to understand about the current metals regime is that Section 232 duties do not replace other duties. They add.
The administration has been explicit about cumulation across its 2026 actions. The Section 201 safeguard tariff-rate quota on quartz surface products that began on August 15, for example, is imposed in addition to the duty rate otherwise applicable, which means it stacks with the Section 301 China duties, the Section 301 forced labour duties, and everything else. The same logic governs the metals derivatives.
Consider an imported steel-bodied article of Chinese origin entered in September 2026. It may carry a most-favoured-nation rate on its non-metal content, a Section 301 China duty from the 2018 tranches, a Section 301 forced labour duty of 10 or 12.5 percent imposed by USTR on July 23 across 60 economies, and a Section 232 metals duty on its steel content. Where the article also falls within a safeguard measure, that too is additive. The effective rate on some product lines now exceeds 100 percent, and for a small number of categories exceeds 145 percent.
That cumulative structure is why classification precision has become the highest-value compliance activity available to an American importer. The difference between two adjacent subheadings can now be forty percentage points of landed cost, and the difference between substantiated and unsubstantiated metal content can be the whole duty base.
Reaction and the comment record
Industry response to the derivative inclusions programme has followed a consistent pattern for two years, and the current round is no exception.
Domestic steel, aluminium and copper producers and their associations support expansion, and they are the petitioners driving it. Their argument is straightforward and not without force: a tariff that covers raw coil but not the finished article made from that coil simply shifts imports one step down the value chain, and the mill sees no benefit. From that perspective, the 407 categories added so far are a correction of an original design flaw rather than an expansion of scope.
Downstream manufacturers and importers oppose expansion, and their argument is equally straightforward. Duties on metal-intensive components raise the input cost of American manufacturing, and where the finished good can be imported more cheaply than the components, the tariff actively encourages offshoring of the assembly step. Every inclusion round produces comments from American manufacturers explaining that the proposal will make their domestic production less competitive, not more.
The comment record on the August proposal is where affected parties should be spending Monday through Thursday. Commerce has, in past rounds, narrowed or declined proposed inclusions where commenters produced specific evidence on three points: that no meaningful domestic production of the article exists, that the metal content is a minor share of value, and that the inclusion would raise costs for American producers of goods further downstream. General objections to tariff policy do not move the analysis. Documented supply-chain evidence sometimes does.
The legal backdrop
Section 232 has become the administration’s preferred instrument for a reason that has nothing to do with metals policy.
In February the Supreme Court invalidated the tariffs imposed under the International Emergency Economic Powers Act, holding that the statute did not authorise them. That decision voided both the fentanyl duties and the reciprocal duties and created a refund obligation now estimated at $166 billion. Customs and Border Protection had paid out $100 billion of that as of July 31 through its Consolidated Administration and Processing of Entries system, and roughly $11.4 billion remains held up pending a Department of Justice appeal over whether finally liquidated entries must be refunded.
Section 232 was not before the Court and emerged intact. Its statutory basis, the national security delegation in the Trade Expansion Act of 1962, has survived every serious constitutional challenge brought against it since the 1970s. The administration has therefore rebuilt and extended coverage through Section 232 wherever it can, and through Section 301 and Section 201 where the national security theory does not fit.
Those other instruments are under attack. Twenty-five state attorneys general, co-led by Oregon, Arizona and California, sued in the Court of International Trade on August 3 challenging the July 23 Section 301 forced labour duties, arguing that investigations into 60 economies completed in about two and a half months without country-specific consultations were a pretext for restoring the invalidated IEEPA tariffs. The CIT has consolidated that case with suits filed by small-business plaintiffs and set a briefing schedule expected to close in early October. Separate litigation targets the expired Section 122 surcharge.
None of that touches the metals derivatives. An importer planning for 2027 should assume that Section 301 and Section 122 liability may be refundable and that Section 232 liability will not be. That asymmetry should drive sourcing decisions, contract drafting and reserve accounting differently than a uniform assumption of legal risk would.
What importers should do
Four actions matter between now and Thursday, and four more matter between now and the eventual effective date of whatever Commerce adopts.
Before the comment deadline: identify whether any of your imported goods fall within the 14 proposed categories, including as parts. Determine the metal content share of value for each affected SKU. If the metal share is small, or if no domestic production of the article exists, file a comment saying so with specifics. And check whether your suppliers are filing, because a coordinated submission from a supply chain carries more weight than isolated objections.
After adoption: obtain metal content certifications from every supplier and keep them in a form that survives an audit five years out. Review your classifications for the affected lines, because derivative inclusions are implemented through new Chapter 99 provisions that interact with your existing subheadings. Reprice contracts that assume current landed cost, and include duty escalation language in anything new. And consider whether first sale valuation, foreign trade zone admission or duty drawback offer any relief on your specific flows, because on a stacked duty structure the value of a legitimate valuation reduction is multiplied across every applicable rate.
The metal content calculation in practice
Because the metal content basis is where most of the operational difficulty lives, it is worth walking through what compliance actually requires.
For each affected article, the importer must declare the value attributable to the steel, aluminium or copper content and the value attributable to everything else. The Section 232 duty applies to the first figure. The MFN rate, and any Section 301 or safeguard duty, applies according to its own terms, generally to the full entered value or to the non-metal portion depending on the specific provision. Getting the split wrong in either direction has consequences: understate the metal content and you face a rate advance with interest; overstate it and you have overpaid with no automatic mechanism for recovery beyond a protest.
The figure has to come from the manufacturer, because only the manufacturer knows the bill of materials. In practice that means a supplier declaration, ideally supported by engineering documentation, specifying the weight and value of each covered metal in the finished article. Suppliers in jurisdictions with no equivalent requirement often resist providing it, and the negotiation over who bears the cost of producing that documentation has become a standard feature of purchase agreements for metal-intensive components.
Where the importer cannot substantiate a split, the practical default is that the Section 232 duty applies to the full value of the article. For a product whose metal content is 30 percent of value, that difference is the gap between an effective 7.5 percent and a full 25 percent. Multiplied across a year of shipments, the documentation cost is trivial against the duty exposure.
Three further complications recur. First, articles with multiple covered metals require separate declarations for each, at each metal’s applicable rate. Second, where the same article is imported from several suppliers with different constructions, the metal content share differs by supplier and cannot be averaged. Third, filled containers, assemblies and kits raise the question of what is being valued at all, and the propane and oxygen cylinders in the current proposal are a clear example of an article whose contents have no metal content but whose vessel is almost entirely steel.
The comment strategy that works
Commerce has now run enough inclusion rounds that a pattern is visible in which objections succeed and which do not.
Objections that succeed are specific and evidentiary. They establish, with named producers and production figures, that no meaningful domestic manufacture of the article exists, which undercuts the displacement theory at its foundation. They quantify the metal content share of value, because an article whose steel content is eight percent of value is a weak candidate for a measure designed to protect steel demand. And they demonstrate downstream harm to American production, showing that the importer uses the article as an input to domestic manufacturing that competes with imported finished goods.
Objections that fail are general. Statements that tariffs raise prices, that the measure is inflationary, or that the petitioner is seeking commercial advantage do not engage the statutory question Commerce is deciding and are routinely noted and set aside.
The third category, and the most underused, is the request for narrowing rather than exclusion. Where a proposed category sweeps in both metal-intensive and metal-light variants of the same product family, a comment that proposes a precise line, by weight, by construction, by subheading, gives Commerce a workable alternative to a binary decision. Several of the 407 categories adopted since 2025 were narrowed at the comment stage in exactly this way.
For the 14 categories now on the table, the strongest narrowing candidates are the musical instruments line, where student-grade and professional-grade instruments differ substantially in copper content and in the availability of domestic alternatives, and the heat exchanger and hydraulic parts lines, where the range of products captured by the description is very wide.
The wider point
The derivative inclusions process is the quietest and most consequential part of American trade policy in 2026. Presidential proclamations on drones, pharmaceuticals and polysilicon generate coverage. A Federal Register notice adding tubas and floor safes to the metals tariffs, with a 21-day comment window in late August, generally does not.
But 407 categories added and 14 more proposed is a structural change in the tariff exposure of American manufacturing, accumulated in increments too small individually to attract attention. Any firm importing a metal-intensive component should assume its product will eventually be proposed for inclusion, and should build the metal content documentation capability now rather than in the three weeks it will have to respond.
The comment window closes Thursday. For the 14 categories on the current list, that is the last opportunity to influence the outcome before the duty attaches.