Sourcing dry gas seals from China

Dry gas seal duty and classification

Heading 8484 covers mechanical seals alongside specified gaskets and gasket assortments. Complete dry gas seal cartridges should be assessed against 8484 20 00 90, the other mechanical seals line. The table shows configurations sharing that line, rather than separate tariff subdivisions. Loose rings, elastomers and gas supply equipment need their own classification assessment.

Read from the UK Trade Tariff on 1 October 2026, the other mechanical seals line carried 0% duty for goods from China. The supplied tariff record lists no anti-dumping or countervailing duty, suspension or import control for that line. Import VAT is normally 20%; see UK import duty and VAT.

Confirm the commodity code using the assembly drawing, materials and shipment contents. The separate tariff description for seals used in manufacturing vehicle air-conditioning compressors should not be selected merely because a seal fits a compressor. See the wider compressor mechanical seals guide.

Specify the compressor interface and seal gas

Give the factory the compressor model, approved assembly drawing, shaft and housing interfaces, axial setting and rotation direction, including the viewing direction. Specify tandem or double arrangement, process gas composition, operating and shutdown pressures, temperature, speed and any reverse rotation. Agree face materials, secondary seal materials and compatibility with the process gas.

Define seal gas cleanliness, dryness and supply conditions, separation gas arrangements, vent connections and leakage acceptance criteria. Agree static and running tests, the test gas and the report format before ordering. Ask for reports tied to each cartridge identifier, rather than a catalogue performance claim.

HSE states that intermediate suppliers must supply safe, compliant products with the correct documentation. Request installation, storage and commissioning instructions for the exact cartridge, and have the compressor engineer assess its suitability. Use factory verification to check the maker's machining, assembly cleanliness and test capability.

Worked duty example

Illustrative example, not a quote: A spare pair of tandem dry gas seal cartridges, illustrative only under 8484 20 00 90, invoiced at £30,000 free on board, with £1,500 of freight and insurance to the UK. The customs value is £31,500. Duty at 0% is £0. Import VAT at 20% is charged on the customs value plus duty, £31,500, so it is £6,300. 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

Fit: measure shaft, housing, locating features and axial setting against the approved drawing; check port positions, connections and rotation markings.

Faces and materials: check face condition and flatness records, groove geometry against the drawing, material certificates and secondary seal identification. Keep protective covers in place during receipt inspection.

Test evidence: match cartridge identifiers to static and running leakage reports; check that test gas, pressure, speed and acceptance criteria match the purchase specification.

Arrival condition: check sealed packaging for moisture, contamination and impact damage; confirm installation fixtures, instructions and storage requirements. Agree the scope through quality inspection.

What goes wrong

A cartridge can fit the shaft but have the wrong axial setting, port arrangement or rotation direction. Substituted face or secondary seal materials can be incompatible with the gas. Scratched faces, damaged grooves and contamination can cause leakage even when the outside dimensions match.

A static leakage result does not demonstrate performance at running conditions. Agree representative tests and review the seal gas supply before commissioning. If inspection or test results differ from the approved specification, isolate the cartridge and obtain an engineering review before installation.

Cambridge China Bridge sources these products for UK businesses, checking the factory and the documents before shipment. See factory verification. For machinery and equipment, see machinery imports.