Seamless tubes and hollow bars

Seamless tubes and hollow bars - overview

Seamless tubes and hollow bars are tubular stainless steel products made without a longitudinal weld. Because they have no seam, they are preferred where strength, pressure containment and fatigue resistance are critical. Hollow bars are a similar form of bar stock with a central bore and are often supplied for subsequent machining into components such as shafts, hydraulic pistons or valve bodies.

What are seamless tubes and hollow bars and how are they made?

Seamless tubes are produced by forming a solid billet into a tube by methods such as hot extrusion, rotary piercing followed by rolling (pilger rolling) or cold drawing. These processes create a continuous, homogeneous wall without a welded joint. Hollow bars are usually produced by piercing or extrusion and are supplied with a ready-made bore for precision machining.

Materials and common stainless grades

We only supply stainless, heat‑resistant and acid‑resistant steels. Common grades you will encounter include:

• 304 / EN 1.4301 (UNS S30400) - general-purpose austenitic stainless steel with good corrosion resistance and formability.
• 304L / low‑carbon variants - better for welded fabrications where intergranular corrosion must be avoided.
• 316 / EN 1.4401 (UNS S31600) - improved corrosion resistance versus 304, commonly used where chlorides or marine atmospheres are present.
• 316L / EN 1.4404 (UNS S31603) - low‑carbon 316 for welding and enhanced resistance to sensitisation.
• Duplex and super‑duplex (e.g. 2205, 2507) - higher strength and improved resistance to chloride stress‑corrosion cracking for demanding offshore and chemical environments.
• High‑alloy and heat‑resistant grades - used where elevated temperature or aggressive media are present (examples include stabilized and nickel‑containing grades).

If you need a specific EN, AISI or UNS designation for an application, please check the product technical data sheet or contact us for confirmation.

Typical applications and industries

Seamless tubes and hollow bars are used across a wide range of sectors, from small workshop projects to large industrial applications:

• automotive and motorsport - driveshafts, hydraulic lines, structural components;
• aerospace - hydraulic tubing, landing gear components (where specified materials and traceability are required);
• oil & gas and offshore - high‑pressure tubing, risers, subsea and topside pipework (duplex/super‑duplex often specified);
• chemical and petrochemical - process lines, heat exchangers and corrosive process environments;
• power generation and energy - boiler tubes, superheater and heat‑resistant applications;
• engineering and manufacturing - precision machined components from hollow bar stock, bearing housings and shafts;
• building services and plumbing - corrosion‑resistant pipework and structural elements;
• small projects and garages - custom exhausts, hydraulic fittings and fabricated components where stainless performance is required.

Benefits and when to choose seamless products

Key advantages of seamless tubes and hollow bars include higher structural integrity under pressure, improved fatigue resistance and more consistent material properties across the section. Choose seamless tubing when you need maximum reliability for pressure service, rotating parts or environments where welds would be a weakness.

Selecting the right product - practical tips

When specifying seamless tubing or hollow bar consider:

• material grade - match corrosion and temperature resistance to the application;
• dimensions - outer diameter (OD), inner diameter (ID) and wall thickness must suit pressure and flow requirements;
• mechanical properties - yield and tensile strengths, especially for load‑bearing applications;
• surface finish and tolerances - cold‑drawn or polished tubes offer tighter dimensional tolerances and better surface quality;
• certification and traceability - for critical work, request material certificates (for example EN 10204 3.1) and test reports;
• additional services - many suppliers offer cut‑to‑length, end‑machining, chamfering or other value‑added services; verify available lead times and minimum order quantities.

How we can help

We stock a wide range of stainless and heat‑resistant seamless tubes and hollow bars in common grades and sizes, and we can advise on material selection for your application. For quotes, cut‑to‑length options or technical data sheets, check the product page or contact our technical sales team - we can help ensure you choose the correct grade and dimensions for safe, cost‑effective performance.