Honed tubes

At a glance

Honed tubes are precision cold-drawn steel tubes with a smooth, dimensionally accurate inner surface, intended for hydraulic and pneumatic cylinder bodies. Max Metal supplies seamless tubes with H8 tolerance to EN 10305-1 (E355+SR) and electric-welded tubes with H9 tolerance to EN 10305-2 (E355+C), as well as HPZ tubes for skiving and roller burnishing and chrome-plated tubes for piston and telescopic assemblies.

Inside diameter tolerance

H8 – seamless · H9 – electric-welded

Standard

EN 10305-1 (seamless) · EN 10305-2 (welded)

Steel grade

E355+SR · E355+C (1.0580)

Inner surface roughness

Ra ≤ 0.4 μm (H8) · Ra ≤ 0.8 μm (H9)

Production lengths

5,000 – 7,000 mm, cut to length on AMADA machines

Supply

From the Plovdiv distribution center to Bulgaria and Europe

Parameters are indicative and depend on the tube type and execution. Send dimensions and quantity for an exact quotation.

Honed tubes (also called cylinder tubes or hydraulic cylinder tubes) are precision steel tubes whose inside diameter is held to a controlled tolerance (H8 or H9) with low roughness. This lets the tube be used directly as the body of a hydraulic or pneumatic cylinder without additional boring and honing of the inner surface.

The smooth inner surface matters for the seals and the piston: it reduces friction and wear, keeps the seal stable at working pressure, and extends cylinder life. That is why selection looks at the inside diameter tolerance, the Ra roughness, straightness, and wall eccentricity together.

Max Metal offers honed tubes as part of its precision steel tube range – seamless cold-drawn tubes with H8 tolerance and electric-welded cold-drawn tubes with H9 tolerance, produced to EN 10305-1 and EN 10305-2.

The choice of tube type depends on working pressure, wall thickness, surface requirements, and the project budget.

• Seamless cold-drawn H8 tubes (EN 10305-1, E355+SR) – no weld seam, eccentricity max 5 %, straightness 0.5 mm / 1000 mm, Ra ≤ 0.4 μm; for high-pressure cylinders and thicker walls.
• Electric-welded cold-drawn H9 tubes (EN 10305-2, E355+C / 1.0580) – 100 % eddy current testing to SEP 1925, eccentricity max 3 %, Ra ≤ 0.8 μm; an economical choice for standard hydraulic and pneumatic cylinders.
• HPZ tubes for skiving and roller burnishing – seamless Ø30 – Ø250 mm or welded Ø30 – Ø160 mm, E355+SR, 20MnV6, or E460+SR; for manufacturers who finish the inside diameter themselves.
• Externally chrome-plated tubes (ISO f7, Ra ≤ 0.20 μm) and internally chrome-plated tubes (H8) – when corrosion resistance and minimal friction are needed for piston bodies, telescopic cylinders, or cylinder bodies.

The ISO 286 tolerance defines the permitted deviation of the inside diameter. H8 is a tighter class than H9 – for the same nominal diameter, a seamless H8 tube gives less size scatter and a smoother surface, which is decisive at high pressure, long strokes, and seals with small clearances.

H9 welded tubes are fully suitable for most standard cylinders and offer a better price-to-quality ratio at thinner walls. 100 % non-destructive testing of the seam (eddy current to SEP 1925 and ultrasonic to SEP 1915) guarantees weld integrity.

• High working pressure, thick walls, long strokes → seamless H8 tubes.
• Standard hydraulic and pneumatic cylinders, price sensitivity → electric-welded H9 tubes.
• You will finish the inside diameter yourself (skiving and roller burnishing) → HPZ tubes.
• Corrosive environment, piston bodies, or telescopic assemblies → externally or internally chrome-plated tubes.

Honed tubes are supplied from the Max Metal distribution center in Plovdiv – 7,500 sq.m of logistics space with covered storage that protects the oiled tube surface from corrosion until installation.

Production lengths are 5,000 – 7,000 mm. When needed, tubes are cut to length on 5 Japanese AMADA machines (up to Ø530 mm), so you receive blanks ready for machining with minimal scrap. For customers with recurring programs we plan buffer stock and coordinated scheduled deliveries.

• Covered storage and protection of oiled surfaces
• AMADA cutting to customer dimensions
• Deliveries in Bulgaria and Europe aligned with the production schedule

A precise technical brief shortens quotation time. Please specify:

• Tube type – seamless H8, welded H9, HPZ, or chrome-plated
• Inside diameter and wall thickness (or outside diameter)
• Length – production length or cut to size, number of pieces
• Quantity and frequency – one-off delivery or recurring program
• Tolerance, surface, and delivery time requirements