What is ST52 seamless pipe?
ST52 is the old DIN name (ST52-3, DIN 1629 for hot-finished seamless, DIN 2391 for cold-drawn) of the fine-grained carbon-manganese steel that EN now calls E355 — E for engineering, 355 MPa minimum yield, material number 1.0580 — the workhorse of seamless mechanical tube. It is not a pressure grade (that is P355) nor a structural hollow section (S355J2H): it is specified by mechanical engineers for parts that are machined, honed, bored, turned and welded into machines, and its selling points are strength with good machinability, a clean seamless wall that can be bored to a cylinder tolerance, and availability in every size from Ø 20 to Ø 406 mm with walls to 40 mm and more. Three product forms cover the trade. Hot-finished tube (EN 10297-1, +AR or +N) is the heavy-wall general-purpose form for machining rings, bushings, axles, rollers and structural machine parts, with generous tolerances and a scaled surface. Cold-drawn tube (EN 10305-1, E355+SR stress-relieved, +N normalised, +C hard) is bright, close-tolerance (OD ±0.1–0.3 mm), and is the starting stock for hydraulic and pneumatic cylinders: honed (H8 bore, Ra ≤ 0.4 µm) or skived and roller-burnished (SRB, Ra ≤ 0.2 µm) tube, ready to cut to stroke length and weld the end caps on, and chrome-plated bar of the same steel for the piston rods. Heavy-wall mechanical tube for machining is the third — chosen instead of solid bar to save 30–60 % of the material when the part is hollow. E355 welds like S355 (no preheat below 20 mm), machines well, and can be induction-hardened or nitrided for wear. We stock cold-drawn and honed cylinder sizes Ø 40–200 mm bore and hot-finished Ø 60–219 mm, and source larger and special sizes from EU and Asian mills.
Seamless pipe — stocked sizes (kg/m)
General seamless sizes; E355 mechanical and cylinder tube is quoted per OD × wall from the EN 10297 / 10305 size ranges — weights per EN 10220.
| NPS | OD (mm) | Wall (mm) | kg/m |
|---|---|---|---|
| ½" | 21.3 | 2 | 0.95 |
| ½" | 21.3 | 7.1 | 2.49 |
| ¾" | 26.9 | 2.3 | 1.4 |
| ¾" | 26.9 | 6.3 | 3.2 |
| 1" | 33.7 | 2.6 | 1.99 |
| 1" | 33.7 | 7.1 | 4.66 |
| 1¼" | 42.4 | 3.2 | 3.09 |
| 1½" | 48.3 | 3.2 | 3.56 |
| 1½" | 48.3 | 9.53 | 9.11 |
| 2" | 60.3 | 3.6 | 5.03 |
| 2" | 60.3 | 9.53 | 11.93 |
| 2½" | 76.1 | 3.6 | 6.44 |
| 3" | 88.9 | 4 | 8.38 |
| 4" | 114.3 | 4.5 | 12.19 |
| 5" | 139.7 | 5 | 16.61 |
| 12" | 323.9 | 8 | 62.32 |
| 355.6 | 8 | 68.58 | |
| 457 | 9.53 | 105.16 | |
| 610 | 9.53 | 141.12 |
EN 10216-1/2 (P235TR2, P235GH) and ASTM A106 Gr. B; other schedules on mill order.
Grades, standards and tolerances
| Grade / standard | Yield (MPa) | Note |
|---|---|---|
| E355 (1.0580) — EN 10297-1 +N | 355 | hot-finished mechanical tube = ST52-3 DIN 1629 |
| E355+SR — EN 10305-1 | 450 (typ.) | cold-drawn, stress-relieved; hydraulic cylinder tube = ST52 BK+S |
| E355+N — EN 10305-1 | 355 | cold-drawn, normalised; for welding and bending |
| E355+C — EN 10305-1 | ≥ 520 | cold-drawn hard; rollers, shafts |
| E235 / E275 (ST37 / ST44) | 235 / 275 | lighter mechanical tube |
| E470 / 20MnV6 | 470 | higher strength, to order |
Chemistry E355: C ≤ 0.22, Si ≤ 0.55, Mn ≤ 1.60, P/S ≤ 0.025. Not for pressure design — use P235GH / P355NH tube for that.
Hydraulic cylinder tube — sizes and tolerances
| Bore (mm) | OD × wall | Bore tolerance | Bore Ra (µm) | Straightness | Use |
|---|---|---|---|---|---|
| 40 | 50 × 5 | H8 | ≤ 0.4 honed / ≤ 0.2 SRB | ≤ 0.3 mm/m | small cylinders, agricultural |
| 50 | 60 × 5 / 63 × 6.5 | H8 | as above | ≤ 0.3 mm/m | tipper, loader |
| 63 | 75 × 6 / 80 × 8.5 | H8 | as above | ≤ 0.3 mm/m | excavator, press |
| 80 | 90 × 5 / 95 × 7.5 / 100 × 10 | H8 | as above | ≤ 0.3 mm/m | construction machinery |
| 100 | 115 × 7.5 / 120 × 10 | H8 | as above | ≤ 0.3 mm/m | cranes, presses |
| 125 | 140 × 7.5 / 150 × 12.5 | H8 | as above | ≤ 0.3 mm/m | heavy presses, mining |
| 160 | 180 × 10 / 190 × 15 | H8 / H9 | as above | ≤ 0.5 mm/m | heavy equipment |
| 200 | 220 × 10 / 230 × 15 | H9 | as above | ≤ 0.5 mm/m | to order |
Other bores and walls per EN 10305-1 and ISO 4394; tube supplied in 6 m or cut to stroke length + allowance. Chrome-plated E355 / CK45 rod for pistons on request.
Lengths and stock
Honed and SRB cylinder tube in the common bores (Ø 40–160) and hot-finished E355 in Ø 60.3–219.1 × 5–20 mm are held by us and our stock partners for despatch within 1–2 weeks; larger, heavier and +C / +N cold-drawn sizes come from the mill in 4–8 weeks. Cut to length on our saws; honed tube cut with end protection.
Machining, honing, welding and heat treatment
E355 machines freely at HSS or carbide speeds for 355-MPa steel; bore and hone hot-finished tube to make cylinders where stock honed tube is not available (allow 1.5–3 mm on the bore). Weld with G3Si1 / E42 consumables, no preheat below 20 mm, stress-relieve welded cylinders at 550–600 °C if the bore is honed afterwards. Induction-harden or nitride for wear; +SR tube must not be heated above 500 °C or it loses its straightness. Cold-draw and bend +N tube; +SR bends only at large radii.
Where it is used
- Hydraulic and pneumatic cylinder barrels (honed / SRB)
- Piston rods, axles, shafts and rollers
- Bushings, rings and machined hollow parts
- Crane, excavator, press and agricultural machine components
- Conveyor rollers and idlers
- Heavy-wall tube for structural machine parts
ST52 seamless vs S355J2H vs P355
S355J2H hollow sections are the structural, welded (or hot-finished) version for buildings and frames — cheaper and not for machining; P355NH / P265GH tube (boiler tube) is the pressure version with elevated-temperature guarantees. E355 / ST52 is the mechanical engineer\'s tube; for lighter machine tube, E235 seamless on the seamless pipe page.
Price
E355 seamless is priced per ton or per metre by form (hot-finished, cold-drawn, honed), size and wall, following the seamless pipe list; honed cylinder tube is priced per metre and carries the largest premium. The bands below are indicative FOB Istanbul for hot-finished mechanical tube and honed cylinder tube.
Bands from our weekly export list (September 2026), FOB Istanbul, full-container quantities, excluding freight and certificates. Firm price per project on RFQ within one working day.
Export and packing
Mechanical tube ships in strapped bundles of 1–2 t on timber with end caps and PE wrap; honed and cold-drawn tube is capped, sleeved individually and packed in wooden crates or padded bundles so the bore and surface arrive undamaged. 18–22 t per 20', 24–26 t per 40' HC in 6 m; heavier walls fill the container by weight. HS 7304.39 / 7304.59.
| Term | Detail |
|---|---|
| MOQ | 500 kg (mixed sizes) |
| Incoterms | FOB Istanbul · CIF / CFR Gulf, Africa · DAP EU, Balkans, Iraq, Caucasus · DAP Aktau |
| Lead time | Cylinder and common sizes 1–2 weeks; mill order 4–8 weeks |
| Packing | Bundles on timber with end caps and PE wrap; honed tube capped and individually sleeved |
| Container / truck | 20' ≈ 18–22 t; 40' HC ≈ 24–26 t |
| Documents | Invoice, packing list, EN 10204 3.1, certificate of origin; 3.2 on request |
| Payment | 30% advance, balance against B/L copy; L/C at sight above 100 t |
Certificates
E355 tube ships with EN 10204 3.1 (heat chemistry, tensile, hardness, delivery condition +SR / +N / +C, dimensions) to EN 10297-1 or EN 10305-1; honed tube adds the bore measurement and roughness report; 3.2 witnessing and ultrasonic testing on request for crane and mining components.
How to order
Specify E355 and the form (EN 10297-1 hot-finished; EN 10305-1 +SR / +N / +C; honed or SRB with bore tolerance), OD × wall or bore × wall, length or cut lengths, quantity, certificate and any straightness / surface / hardness requirements; cylinder makers may send the cylinder drawing.
Standards
- EN 10297-1 — seamless circular tubes for mechanical engineering (E355, hot-finished)
- EN 10305-1 — cold-drawn seamless precision tubes (E355+SR / +N / +C)
- DIN 1629 / DIN 2391 (historic ST52-3 / ST52 BK+S)
- ISO 4394 / ISO 6020 honed cylinder tube; EN 10204 3.1
Grades
Grade data sheets (chemistry, mechanicals, equivalents) are on our reference site: E355 · S355J2H · P235GH
Frequently asked questions
What is ST52 seamless pipe?
Seamless mechanical tube in the 355 MPa fine-grain steel now designated E355 (1.0580) — hot-finished (EN 10297-1) or cold-drawn (EN 10305-1) — used for hydraulic cylinders, shafts, rollers and machined parts. ST52-3 is the historic DIN name.
What is the EN equivalent of ST52 tube?
E355 (material 1.0580): EN 10297-1 for hot-finished (= DIN 1629 ST52-3) and EN 10305-1 E355+SR / +N / +C for cold-drawn (= DIN 2391 ST52 BK+S / NBK / BK).
What is honed tube?
Cold-drawn E355+SR tube whose bore has been honed to an H8 tolerance and Ra ≤ 0.4 µm (or skived and roller-burnished to Ra ≤ 0.2) so it can be used directly as a hydraulic cylinder barrel.
Can ST52 tube be used for pressure pipe or structures?
It is a mechanical grade without pressure or structural certification; use P235GH / P355NH tube for pressure and S355J2H hollow sections for structures.
What sizes are in stock?
Honed cylinder tube in bores Ø 40–160 and hot-finished E355 Ø 60.3–219.1 × 5–20 mm within 1–2 weeks; larger and special sizes 4–8 weeks from the mill.