Seamless hydraulic steel tube — cold drawn, with no weld seam — in grades E355 (ST52.4) and E235 (ST37.4), NBK finish: phosphated and normalised, oiled inside and out. Supplied in 6 metre lengths with an EN 10204 3.1 certificate. It is the wall, not the OD, that sets the pressure.
State the OD × wall, grade and total metres — quotes back within 2 working hours.
| Outside diameter | 4 mm to 190 mm |
|---|---|
| Material | E355 (ST52.4) · E235 (ST37.4) |
| Dimensional standard | DIN 2391/C (DIN EN 10305-1) · DIN 2445/2 (DIN EN 10305-4) |
| Length | 6 metres per length |
| Manufacture | Cold drawn, seamless — drawn from billet, no weld seam |
| Finish | NBK — phosphated & normalised, oiled · galvanized on request |
| Certificate | EN 10204 3.1 mill test certificate as standard |
Working & burst pressure tables per size and grade are in the catalogue below, as printed — calculated per DIN 2413.
| At a glance | E355 (ST52.4) | E235 (ST37.4) |
|---|---|---|
| Min yield | 355 MPa | 235 MPa |
| Tensile | 490–630 N/mm² | 340–480 N/mm² |
| e.g. 10×2.0 | 799 bar | 565 bar |
| Character | Thinner wall, lighter | More ductile, welds easily |
Hydraulic steel tube carries fluid between hydraulic components — fittings, valves, flanges, cylinders and power units. Being cold drawn seamless, its dimensional tolerances are tight, its strength higher and its surface smoother than hot-finished tube — which is what lets a compression fitting bite and seal on the outside. Ordered by OD, wall and grade. Unlike Walform tube, whose end is pre-formed as a sealing face and made to order.
With a wheel cutter or mechanical cut — deburr the bore after cutting.
With a hydraulic or manual bender, radius no tighter than 3× OD — a 42 mm tube needs at least a 126 mm radius.
Bevel the weld preparation first; filler to DIN EN 1600 / DIN EN 12072. The NBK finish is oiled — degrease the weld zone first, or the oil becomes porosity in the weld.
After the hydraulic components and equipment are connected in place. Hold vibration down with pipe clamps — pressurised fluid will shake an unsupported tube.
Tube weight: kg/m = 0.02466 × wall × (OD − wall), both in mm — a 42 mm OD tube with a 4.0 mm wall is 3.748 kg/m.
Pressure rating factor by temperature as printed
| Temperature | Rating factor |
|---|---|
| −40 °C / −40 °F | 0.90 |
| 120 °C / 248 °F | 1.00 |
| 150 °C / 302 °F | 0.89 |
| 175 °C / 347 °F | 0.89 |
| 200 °C / 392 °F | 0.83 |
Tube vs hose comparison
| Attribute | Tube | Hose |
|---|---|---|
| Heat resistance | High — holds its shape | Low — expands at high temperature |
| Cost | Cheaper, readily available | More expensive |
| Durability | Highly durable | Limited lifespan |
Construction plant, agricultural machines and manufacturing equipment — where E355’s weight saving pays off on moving machines.
Hydraulic fracturing, well drilling and piping systems — fluid transfer and control that must stay reliable in harsh environments.
Steering gear, anchor handling and cargo handling on ships and offshore platforms.
Power packs, presses and production lines — high-pressure runs between hydraulic components.
Full dimension and wall tables are in the catalogues. Sizes are in the catalogue; stock and price are not — send the list and we confirm both. More in the catalogue library.
It depends on OD, wall and grade — calculated per DIN 2413 at normal temperature. Examples: 10 mm OD × 2.0 mm is 565 bar in E235 and 799 bar in E355; 42 mm OD × 4.0 mm is 269 bar in E235. Full working and burst tables per size are in the catalogue above, as printed.
E355 is the higher-tensile grade — minimum yield 355 MPa. It takes more pressure at the same wall, so a thinner wall often does the job and the assembly gets lighter. E235 has lower carbon: more ductile, easier to weld and bend. Choose by what constrains you — pressure or fabrication. Send the working pressure and we help pick.
Phosphated and normalised, oiled inside and out. The phosphate gives corrosion resistance; normalising relieves the cold-drawing stresses and makes the steel tougher and more formable — that is what lets the tube be bent in the field. Hot-dip galvanizing (best protection, outdoor/marine) or electro (thin uniform coat, indoors) available on request.
Seamless. The tube is drawn from a billet, so there is no weld seam anywhere in the wall — which is what makes the pressure rating valid around the full circumference.
Yes — an EN 10204 3.1 mill test certificate as standard: chemical analysis and mechanical results per heat, plus flattening, flaring and 100% eddy current tests. EN 10204 3.2 countersigned by a third-party inspector can be arranged if the contract requires it — say so before the order.
Minimum cold bend radius 3× OD — a 42 mm tube needs at least a 126 mm radius. Weight: kg/m = 0.02466 × wall × (OD − wall), both in mm — 42 × 4.0 mm = 3.748 kg/m.
Yes — held as ready stock in our regional warehouses in Singapore and Malaysia, in both E355 and E235 at once, so the grade is a design choice rather than whatever happens to be available. Out within 24 hours of your PO.
Send the OD and wall (or ID and wall), grade, standard, total metres and length preference via WhatsApp ★ Google reviews ▶ YouTube channel or the contact form — quotes back within 2 working hours. A drawing or a photo of the old tube’s marking works too.
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