Sourcing expanded PTFE membranes from China
Expanded PTFE membranes from China have a 6% base UK duty on the relevant heading 3921 lines, with qualifying relief bringing duty to 0%. Match the membrane construction and intended use to the full tariff description, and check UK REACH for substances in the finished article. Cambridge China Bridge sources expanded PTFE membranes.
6% base duty, with conditional relief
Read from the UK Trade Tariff on 1 October 2026, heading 3921 covers other plastic plates, sheets, film, foil and strip. For expanded PTFE membranes, distinguish unsupported cellular membrane, supported strip and laminated sheet. The table includes possible classification routes, rather than interchangeable codes. For the wider film comparison, see non-cellular PTFE film.
The selected lines carry 6% base duty from China, with no anti-dumping or countervailing duty recorded. The specified polyester-backed membrane under 3921 19 00 50 has a 0% suspension. Under 3921 19 00 99, supported microporous PTFE strip for kidney-dialysis filter manufacture has 0% authorised-use relief; its separate general suspension names other materials. Under 3921 90 60 90, the suspension names fabric-based fluorinated ion-exchange membranes for chlor-alkali cells, alongside offshore-wind rotor-blade authorised-use relief. These are specific concessions, not blanket membrane relief.
The snapshot records no attached controls for the selected lines except a restriction on entry into free circulation under 3921 19 00 99 concerning ozone-depleting substances. Importing those substances into Great Britain requires a licence; confirm the membrane declaration requirement with your customs broker. Authorised-use relief requires authorisation. Send the broker the layer composition, support material, dimensions, performance reports and intended use to confirm the commodity code and any suspension conditions.
| Goods | Commodity code | Duty | Anti-dumping or countervailing duty on China |
|---|---|---|---|
| Specified porous PTFE membrane laminated to polyester non-woven cloth | 3921 19 00 50 | 6% | None |
| Specified supported microporous PTFE strip for medical filter manufacture | 3921 19 00 55 | 6% | None |
| Other cellular plastic membrane, subject to classification | 3921 19 00 99 | 6% | None |
| Other addition-polymer composite sheet or film, subject to classification | 3921 90 60 90 | 6% | None |
Specify the membrane and its support
Specify expanded PTFE construction, unsupported or laminated form, backing fibre, adhesive, surface treatment, thickness tolerance, usable width and roll length. State whether the membrane must repel water or wet readily. Define airflow at an agreed pressure difference, water entry pressure, filtration performance and the operating media. Agree test conditions and acceptance criteria before approving the sample.
UK REACH generally applies to substances in articles. Products containing persistent organic pollutants may only be used under the stated exceptions to the ban. Ask for composition declarations covering the membrane, coatings and adhesive, and agree targeted chemical testing with a testing and certification provider. Keep reports tied to the supplied construction and batch.
Worked duty example
Illustrative example, not a quote: 20 rolls of expanded PTFE membrane for a filtration trial, without duty relief; illustrative under 3921 19 00 99, invoiced at £12,000 free on board, with £1,500 of freight and insurance to the UK. The customs value is £13,500. Duty at 6% is £810. Import VAT at 20% is charged on the customs value plus duty, £14,310, so it is £2,862. Import taxes total £3,672; a VAT-registered importer can usually reclaim the VAT, so the lasting cost is the £810 of duty. The import duty and VAT guide explains each step.
Inspection checklist
Construction: compare the membrane, backing, adhesive and treated face with the approved sample; check for substituted support fabric or loose bonding.
Dimensions: measure thickness across the usable width, check slit edges and reconcile roll labels and supplied length with the packing list.
Performance: compare airflow, water entry pressure and filtration results under the agreed conditions; inspect for pinholes, tears and blocked areas.
Packing: check winding tension, crushed cores, creases, contamination and batch identification before shipment and on arrival. Use an agreed inspection brief.
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What goes wrong
A sample can pass while production rolls vary in pore structure or coating coverage. Adhesive can obstruct airflow, backing can separate during converting, and winding can leave permanent creases. A water-repellent sample may behave differently after surface treatment or exposure to the intended liquid.
Another failure is costing the order with a suspension that matches neither the supplied laminate nor its use. Obtain reports for the actual construction, retain batch samples and trial the membrane in your filter or vent assembly before releasing it to production.
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.
Frequently asked questions
What is the UK import duty on expanded PTFE membranes from China?
The relevant lines have a 6% base duty. Qualifying specified membranes or authorised uses can receive 0% relief. The tariff snapshot records no anti-dumping or countervailing duty on the selected lines.
Does every polyester-backed PTFE membrane qualify for zero duty?
No. For 3921 19 00 50, compare the support, total thickness, water entry pressure and air permeability with the full tariff description and suspension conditions.
What should I test on an expanded PTFE membrane sample?
Check airflow, water entry pressure, filtration performance, thickness variation and backing adhesion under agreed conditions. Trial the membrane with the intended liquid or gas and in the actual assembly.
Can I use a supplier's report for a different membrane grade?
Ask for evidence covering the supplied membrane, support, adhesive and surface treatment. A report for another construction does not establish that your rolls meet the agreed specification.