SITCSection 7
U.S. imports of auxiliary plant for use with boilers (SITC 71121) totaled $4.5M in April 2026, traded with 16 countries.
Importers of Auxiliary Plant for Use with Boilers paid $399K in duties in April 2026 — an effective duty rate of 30% on $1.3M in dutiable value, based on actual customs collections rather than the published tariff schedule. Auxiliary Plant for Use with Boilers imports of $4.5M in April 2026 ran 60% below the year-to-date monthly average of $11.3M.
Last updated: April 2026 dataEconomizers, superheaters, soot blowers, waste-heat recovery units, and similar auxiliary equipment that support steam-generating and central heating boilers fall under this heading. These components are critical to boiler efficiency in power generation, refining, and heavy manufacturing, and their classification can be contested when they are imported as part of a larger boiler system versus as standalone equipment. Correct classification as auxiliary plant rather than as a boiler part or a separate industrial machine determines the applicable duty treatment.
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Auxiliary plant refers to complete functional units—such as economizers, feedwater heaters, or soot blowers—that serve the boiler system but are not integral structural components of the boiler itself. Parts, by contrast, are components that make up the boiler or auxiliary unit. The distinction matters because auxiliary plant and parts carry separate SITC headings and may attract different duty rates.
Potentially yes. When auxiliary equipment arrives as part of a complete industrial plant under a single contract, importers sometimes explore composite goods or sets classification rules. However, each article is generally classified separately unless it meets the strict criteria for an unassembled machine set. A licensed customs broker should review the contract structure and shipping documentation before entry.
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| Country | Imports | Exports | Balance |
|---|---|---|---|
| CANADA | $3.2M | $3.4M | +$232K |
| CHINA | $876K | $400K | -$476K |
| DOMINICAN REPUBLIC | -- | $395K | +$395K |
| ECUADOR | -- | $255K | +$255K |
| MALAYSIA | $177K | -- | -$177K |
Monthly import values over time