Sourcing seamless cylinder tubes from China

Duty on gas-cylinder tube stock

Read from the UK Trade Tariff on 1 October 2026, heading 7304 covers seamless iron or steel tubes, pipes and hollow profiles. This guide concerns open-ended steel tube stock bought for gas-cylinder manufacture. The table gives possible alloy steel classifications, subject to the exact material and manufacturing process. For wider applications, see seamless mechanical steel tubing.

The supplied relevant lines all carry 0% duty for goods from China. They show no anti-dumping or countervailing duty, no steel measure, no suspension and no attached import control. Import VAT is normally 20%. These tariff findings do not establish whether the tube is suitable for a particular cylinder design.

Send your customs broker the steel composition, production method, outside diameter, carbon-equivalent calculation and description of the goods as imported. Have the commodity code confirmed before ordering, especially if the goods have already been formed into cylinder shells.

Specify stock for the cylinder-forming process

Ask the cylinder manufacturer to approve the tube specification before seeking quotations. State the steel grade and chemistry, outside diameter, minimum wall thickness, wall eccentricity, ovality, straightness, cut length and end condition. Agree the delivery heat-treatment condition and the allowance needed for forming the base and neck.

Specify the material certificate, heat identification, mechanical tests and non-destructive examination records you expect. Agree acceptance criteria for internal laps, cracks, surface defects and decarburisation. Ask which mill makes the tube and which site performs heat treatment; factory verification can check those production arrangements.

The finished product must comply with applicable legislation when placed on the market. Agree the finished-cylinder compliance route separately from the tube purchase. HSE says obsolete design standards and specifications must not be used to manufacture new transportable pressure equipment.

Worked duty example

Illustrative example, not a quote: Illustrative trial batch of cold-drawn alloy steel gas-cylinder tube stock under 7304 51 89 30, invoiced at £6,000 free on board, with £4,000 of freight and insurance to the UK. The customs value is £10,000. Duty at 0% is £0. Import VAT at 20% is charged on the customs value plus duty, £10,000, so it is £2,000. 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

Traceability: match bundle labels and tube markings to heat numbers on the mill certificates; check chemistry and mechanical results against the agreed specification.

Geometry: measure wall thickness around the circumference and along sampled tubes, then check ovality, straightness, cut length and end squareness.

Condition: inspect the bore and outside surface for laps, cracks, scale, corrosion and handling dents; compare examination reports with the delivered heat and batch.

Process suitability: review the agreed heat-treatment records and forming-trial results before releasing stock to production. Record arrival findings using the quality inspection guide.

What goes wrong

A tube can match the nominal diameter yet have an eccentric wall, leaving too little material locally after forming. Internal laps may be hidden by scale, mixed heats can break traceability, and an unsuitable delivery condition can cause cracking during base or neck forming.

Agree how defects will be assessed before the order. Keep affected bundles separate when markings, certificates or measurements disagree, and obtain the cylinder manufacturer's decision before processing them. A generic mill certificate cannot establish compliance of the finished cylinder.

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.