Sourcing engine piston assemblies from China
UK duty ranges from 0% for aircraft engine parts to 2% for ordinary petrol and diesel piston assemblies from China. Match the code to the engine application; a suspension on another component does not establish relief for your assembly. Cambridge China Bridge sources engine piston assemblies.
Duty depends on the engine application
Read from the UK Trade Tariff on 4 October 2026, heading 8409 covers parts suitable for use solely or principally with the engines of heading 8407 or 8408. Ordinary spark-ignition piston assemblies normally fall under 8409 91 00 90, and diesel assemblies under 8409 99 00 90. The aircraft lines are included for specialist buyers.
The ordinary petrol and diesel lines carry 2% duty for goods from China; the aircraft lines carry 0%. The supplied tariff records show no anti-dumping or countervailing measures and no attached import controls on these selected lines. The ordinary lines also contain narrowly described suspensions for other components. Do not assume those suspensions cover piston assemblies; ask your customs broker to check the exact description.
Confirm the commodity code against the intended engine and assembly contents before ordering. Rings, pins or other components supplied separately need their own classification check. See the wider engine parts guide for related components.
| Goods | Commodity code | Duty | Anti-dumping or countervailing duty on China |
|---|---|---|---|
| Piston assemblies for spark-ignition engines, other | 8409 91 00 90 | 2% | None |
| Piston assemblies for diesel and other engines, other | 8409 99 00 90 | 2% | None |
| Aircraft piston assemblies for the specified duty-free aircraft category | 8409 10 00 20 | 0% | None |
| Aircraft engine piston assemblies, other | 8409 10 00 90 | 0% | None |
Specify the piston, rings and pin as an assembly
Give the engine reference, original equipment part number and drawing revision. Define whether the supply includes rings, pins and retaining clips. Specify bore size, compression height, crown shape, valve pockets, ring groove dimensions, pin bore fit and any offset. Agree the alloy, manufacturing process, heat treatment, coating and weight tolerance.
Approve a measured sample against the drawing and test-fit it with the intended mating parts. Keep the accepted sample and inspection report as the production reference. Where assemblies are sold as consumer products, UK businesses making, importing, distributing or selling them are responsible for their safety.
Worked duty example
Illustrative example, not a quote: An illustrative workshop stock order of diesel engine piston assemblies under 8409 99 00 90, invoiced at £8,000 free on board, with £1,200 of freight and insurance to the UK. The customs value is £9,200. Duty at 2% is £184. Import VAT at 20% is charged on the customs value plus duty, £9,384, so it is £1,876.80. Import taxes total £2,060.80; a VAT-registered importer can usually reclaim the VAT, so the lasting cost is the £184 of duty. The import duty and VAT guide explains each step.
Inspection checklist
Dimensions: measure skirt diameter at the agreed position, compression height, ring grooves and pin bores against the drawing; repeat critical measurements on arrival.
Material and finish: compare alloy and heat-treatment records with the order; check pin hardness, casting defects, burrs and coating adhesion.
Assembly contents: check ring profile and orientation, pin fit and retaining clips against the approved sample; confirm that mixed engine variants have not been packed together.
Traceability and packing: match part numbers and batch marks to inspection records; check machined surfaces for rust and transit damage. Use the inspection guide to plan shipment checks.
What goes wrong
An interchange claim can hide a different crown, compression height or pin arrangement. Wrong alloy or heat treatment can cause scuffing or cracking; incorrect ring grooves and pin bores cause fit problems. A visually similar sample does not replace dimensional measurements.
Keep variants separated and quarantine assemblies that fail the agreed checks. Record the affected batch and compare retained samples with the delivered parts before accepting a replacement. Poor protection can leave pins and rings corroded even when the pistons look sound.
Cambridge China Bridge sources these products for UK businesses, checking the factory and the documents before shipment. See factory verification.
Frequently asked questions
What is the UK import duty on piston assemblies from China?
Ordinary petrol and diesel piston assemblies carry 2% duty. Aircraft engine parts carry 0%. The selected tariff lines show no anti-dumping or countervailing measures; confirm the engine application and exact code.
What should a piston assembly include?
Define the contents in the order: piston, rings, pin and retaining clips as applicable. Match each component to the engine reference and approved drawing rather than relying on the supplier's use of “complete”.
How do I check that replacement pistons fit?
Compare the original equipment part number, crown geometry, compression height, ring grooves and pin arrangement. Measure an approved sample and test-fit it with the intended mating parts.
Which defects should I check when the goods arrive?
Check ring grooves and pin bores for dimensional errors, surfaces for burrs or coating damage, pins and rings for rust, and cartons for mixed variants. Match batch marks to the material and inspection records.