Sourcing Invar alloy wire from China

Invar wire classification and UK duty

Read from the UK Trade Tariff on 1 October 2026, heading 7229 covers wire of other alloy steel. For Invar wire, check the residual line 7229 90 90 00 against the actual composition and supplied form. The table shows supply formats sharing that line, rather than separate tariff subdivisions. See the wider alloy steel and welding wire guide.

The supplied tariff data gives 0% duty for goods from China, with no anti-dumping or countervailing duty, steel measure or suspension recorded. It attaches import and export waste controls. Environment Agency guidance for England says waste shipment controls apply only to waste. For a China shipment containing scrap or material whose waste status is uncertain, ask the customs broker to confirm the attached import requirement before dispatch.

Confirm the commodity code using the composition certificate and product description. Confirm with HMRC or your customs broker whether these tariff lines fall within the UK carbon border adjustment mechanism and when any requirements apply. Ask the supplier for emissions information when planning future purchases; see the UK carbon border adjustment guide.

Specify expansion performance and wire condition

Specify the exact alloy designation and permitted chemistry, diameter and tolerance, roundness, tensile properties, annealed or cold-drawn condition, and surface finish. Define the thermal expansion acceptance criterion over your operating temperature range and agree the test method. Ask for results linked to the supplied heat and final processing condition, rather than a generic Invar brochure.

Agree spool dimensions, winding direction, permitted joints, usable length, protective wrapping and heat-number traceability. Trial the wire in your forming, tensioning or assembly process before approving production. UK REACH generally covers individual substances on their own, in mixtures or in articles; ask a compliance adviser to assess the supplied wire and any coating for your intended use.

Worked duty example

Illustrative example, not a quote: Illustrative small-business order of Invar alloy wire on spools; FOB and freight values are illustrative, not a quotation under 7229 90 90 00, invoiced at £22,000 free on board, with £2,500 of freight and insurance to the UK. The customs value is £24,500. Duty at 0% is £0. Import VAT at 20% is charged on the customs value plus duty, £24,500, so it is £4,900. With no duty, the only import tax is the VAT, which a VAT-registered importer can usually reclaim. The import duty and VAT guide explains each step.

Inspection checklist

Chemistry and identity: match the heat certificate, alloy designation and spool labels; arrange composition testing where identity is uncertain.

Expansion and condition: check the thermal expansion report, test temperature range and heat treatment against the agreed specification.

Dimensions and surface: measure diameter and roundness along sampled wire; inspect for scratches, oxide, lubricant residue and kinks.

Winding and packing: check spool damage, tangles, joints, protective wrapping and batch separation on arrival. Agree sampling through the quality inspection guide.

What goes wrong

A supplier may offer another nickel-iron alloy under a loose Invar description. Chemistry alone also leaves the expansion performance of the delivered wire unproven. A report for a different heat or processing condition does not establish that the purchased wire meets your specification.

Kinks, crossed winding and damaged spool flanges can interrupt feeding or tensioning. Agree how to investigate failures using retained samples and traceable test results. Keep questionable batches separate until the supplier and buyer have resolved the discrepancy.

Cambridge China Bridge sources these products for UK businesses, checking the factory and the documents before shipment. See factory verification. For repeat volumes, see container programmes.