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Solitaire Overseas is a leading ST35 / ST35.8 carbon steel tube manufacturer, supplier, and exporter based in Mumbai, India. We stock and supply a comprehensive range of DIN 2391 ST35 precision seamless tubes and DIN 17175 ST35.8 boiler tubes in seamless and cold-drawn variants, available in standard and custom sizes to suit demanding industrial specifications.
Our tubes are manufactured from fully killed, Al-treated carbon steel compliant with DIN 17175 Clause 5.1 for ST35.8 and DIN 2391 for ST35. They are tested to EN 10204 3.1 mill test certificate requirements, with EN 10204 3.2 third-party witnessing available on request. Every consignment ships with full material traceability documentation, making us a preferred ST35 pipe supplier in India for power plants, refineries, and OEMs across Europe, the Middle East, and Southeast Asia.
ST35 tubes are low-carbon, seamless precision steel tubes manufactured to DIN 2391. The grade designation \"St35\" refers to a minimum tensile strength of 350 N/mm² in the normalised condition. These tubes are engineered for close-tolerance hydraulic lines, pneumatic systems, and general precision engineering where tight OD/wall tolerances and surface quality are critical.
ST35.8 tubes fall under DIN 17175 — the German standard for seamless steel tubes intended for elevated-temperature pressure service. The \".8\" suffix indicates suitability for use in boilers, superheaters, heat exchangers, and steam pipelines at service temperatures within the allowable stress range published in DIN 17175 (up to 450-500°C per stress tables; consult applicable design code for specific operating conditions). The material is classed as fully killed steel, ensuring homogeneous microstructure and predictable long-term creep behaviour.
Both grades have been widely adopted in European engineering and continue to be specified by process industries globally, often replacing older DIN 2448 or DIN 2458 specifications.
Note: DIN 2391 ST35 has been superseded by EN 10305-1 (E235). DIN 17175 ST35.8 has been superseded by EN 10216-2 (P235GH). Both DIN and EN designations remain in active use on legacy and new project specifications.
| Parameter | ST35 (DIN 2391) | ST35.8 (DIN 17175) |
|---|---|---|
| Standard | DIN 2391 | DIN 17175 |
| EN Material Number | 1.0308 | 1.0305 |
| Primary Use | Precision, hydraulic and pneumatic | Boilers, pressure vessels and heat exchangers |
| Max. Service Temperature | Up to 300°C for general hydraulic/pneumatic service | 450-500°C per DIN 17175 allowable stress tables; consult application code |
| Fully Killed Steel | Not mandatory | Mandatory |
| Tensile Strength | 480 N/mm² BK; 340-470 N/mm² NBK | 360-480 N/mm² |
| Minimum Yield Strength | 235 N/mm² NBK; 315 N/mm² BKS | ≥235 N/mm² |
| ASTM Approximate Equivalent | ASTM A519 mechanical tubing | ASTM A210 Grade A-1 |
| Common Delivery Conditions | BK, BKW, BKS, GBK, NBK | Normalised (NBK), annealed |
Download full St35 St35.8 Tube Specifications.pdf
| Standard | Grade | C (max) | Si (max) | Mn (min) | P (max) | S (max) |
|---|---|---|---|---|---|---|
| DIN 2391 | St35 | ≤0.17% | ≤0.35% | ≥0.40% | 0.025% | 0.025% |
| Standard | Grade | C (max) | Si | Mn | P (max) | S (max) | Mo | Cr |
|---|---|---|---|---|---|---|---|---|
| DIN 17175 | St 35.8 | ≤0.17% | 0.10-0.35% | 0.40-0.80% | ≤0.040% | ≤0.040% | — | — |
| Condition | Code | Tensile Strength (N/mm²) | Yield Strength (N/mm²) | Elongation (%) |
|---|---|---|---|---|
| Cold Drawn (Hard) | BK | 480 | — | 6 |
| Cold Drawn (Soft) | BKW | 420 | — | 10 |
| Cold Drawn + Stress Relieved | BKS | 420 | 315 | 14 |
| Soft Annealed | GBK | 315 | — | 35 |
| Normalised | NBK | 340-470 | 235 | 25 |
| Standard | Grade | Tensile Strength (N/mm²) | Yield Strength (N/mm²) | Elongation (%) |
|---|---|---|---|---|
| DIN 17175 | St 35.8 | 360-480 | ≥235 | ≥25 |
Engineers specifying DIN grades for international projects often need cross-reference data. The table below provides approximate equivalents — always verify against the relevant standard for your application.
| Grade | DIN | EN | ASTM / ASME Approx. | BS Approx. | JIS Approx. |
|---|---|---|---|---|---|
| ST35 | DIN 2391 / 1.0308 | EN 10305-1 E235 | ASTM A519 / SAE 1020 | BS 3601 ERW 320 | JIS G3441 STK290 |
| ST35.8 | DIN 17175 / 1.0305 | EN 10216-2 P235GH | ASME SA210 Gr. A-1 | BS 3059 Pt1 Gr 320 | JIS G3461 STB340 |
Note: ST35.8 is a German designation; the current EN replacement is P235GH per EN 10216-2. Many project specifications still reference the DIN designation.
DIN 2391 defines five delivery conditions for ST35 precision tubes. Selecting the correct condition ensures you receive the right balance of strength, ductility, and surface finish for your application.
| Code | Condition | Typical Use Case |
|---|---|---|
| BK | Cold Drawn, hard/as-drawn | Maximum strength; hydraulic cylinders and precision engineering |
| BKW | Cold Drawn Soft | Moderate strength with improved ductility; bending applications |
| BKS | Cold Drawn + Stress Relieved | Reduced residual stress; precision components and close-tolerance assemblies |
| GBK | Soft Annealed | Maximum ductility; deep drawing and severe cold forming |
| NBK | Normalised | Balanced properties; general structural and boiler applications |
| Applicable Standards | DIN 2391, DIN 17175, DIN 2448, EN 10216-2, EN 10305-1, ASTM, ASME, JIS, BS |
|---|---|
| Seamless Tube OD | 4 mm to 219 mm |
| Seamless Wall Thickness | 0.5 mm to 20 mm |
| Welded / ERW Tube OD | 5.0 mm to 1219.2 mm; confirm grade applicability for code-critical service |
| SWG / BWG Range | 10 SWG to 20 SWG |
| Length Options | Single random, double random, standard and cut-to-length |
| Manufacturing Process | Cold drawn, hot drawn, bright annealed, normalised and hot extruded |
| Tube Types | Seamless, ERW, welded, fabricated, CDW, DOM and CEW |
| End Finish | Plain end, bevelled end, threaded and screwed |
| Value-Added Services | Draw and expansion, electro and commercial polish, annealing, pickling, bending and machining |
For dull detailed specification , read out blog Complete ST35 / ST35.8 Tube Specifications Guide
We supply ST35 and ST35.8 tubes across a wide dimensional range from Schedule 5S through Schedule XXS. The tables below cover nominal diameters from 6 mm (1/8") to 914 mm (36"). For sizes outside the listed range or for large-diameter ST35 tubes, please contact our technical team.
| OD Range (mm) | 4-30 | 31-40 | 41-50 | 51-60 | 61-70 | 71-80 | 81-90 | 91-100 |
|---|---|---|---|---|---|---|---|---|
| OD Tolerance (mm) | ±0.08 | ±0.15 | ±0.20 | ±0.25 | ±0.30 | ±0.30 | ±0.40 | ±0.45 |
Wall thickness tolerance: ±10%.
Weights in kg/m. OD and wall thickness (WT) in mm.
| NPS (A) | NPS (B) | OD | SCH 5S WT | SCH 5S kg/m | SCH 10S WT | SCH 10S kg/m | SCH 40 WT | SCH 40 kg/m | SCH 80 WT | SCH 80 kg/m |
|---|---|---|---|---|---|---|---|---|---|---|
| 6 | 1/8 | 10.3 | 1.00 | 0.23 | 1.20 | 0.27 | 1.73 | 0.37 | 2.41 | 0.47 |
| 8 | 1/4 | 13.7 | 1.20 | 0.37 | 1.65 | 0.49 | 2.24 | 0.64 | 3.02 | 0.82 |
| 10 | 3/8 | 17.2 | 1.20 | 0.47 | 1.65 | 0.63 | 2.31 | 0.87 | 3.20 | 1.12 |
| 15 | 1/2 | 21.3 | 1.65 | 0.81 | 2.11 | 1.02 | 2.77 | 1.29 | 3.73 | 1.64 |
| 20 | 3/4 | 26.7 | 1.65 | 1.03 | 2.11 | 1.30 | 2.87 | 1.71 | 3.91 | 2.93 |
| 25 | 1 | 33.4 | 1.65 | 1.31 | 2.77 | 2.13 | 3.38 | 2.54 | 4.55 | 3.29 |
| 40 | 1½ | 48.3 | 1.65 | 1.93 | 2.77 | 3.16 | 3.68 | 4.11 | 5.08 | 5.49 |
| 50 | 2 | 60.3 | 1.65 | 2.42 | 2.77 | 3.99 | 3.91 | 5.52 | 5.54 | 7.60 |
| 80 | 3 | 88.9 | 2.11 | 4.59 | 3.05 | 6.56 | 5.49 | 11.47 | 7.62 | 15.51 |
| 100 | 4 | 114.3 | 2.11 | 5.93 | 3.05 | 8.50 | 6.02 | 16.07 | 8.56 | 22.66 |
| 150 | 6 | 168.3 | 2.77 | 11.47 | 3.43 | 14.04 | 7.11 | 28.69 | 10.97 | 43.21 |
| 200 | 8 | 219.1 | 2.77 | 15.00 | 3.76 | 20.27 | 8.18 | 43.20 | 12.70 | 65.63 |
Request the full schedule chart (SCH 5S–XXS, up to 36" OD) or view the complete ST35/ST35.8 specifications guide.
Indicative prices for DIN 17175 ST35.8 seamless tubes. Prices vary with quantity, size, and market conditions — contact us for a live quotation.
| Description | Price (INR/kg) | Price (USD/kg) | Price (AED/kg) |
|---|---|---|---|
| CS Seamless DIN 17175 ST35.8, fully killed — 27 x 2.8 x 11-11.8 mm | INR 54 | $0.76 | AED 2.78 |
| CS Seamless, hot finished, DIN 17175 ST35.8 | INR 53 | $0.74 | AED 2.73 |
| CS Seamless, hot finished — 27 x 3.0 x 10500-11800 mm | INR 57 | $0.80 | AED 2.94 |
| Hot finish CS seamless mother pipe — 30 x 2.6 x 9800-10100 mm | INR 43 | $0.60 | AED 2.22 |
Prices are ex-Mumbai warehouses and subject to change. Bulk discounts available. IBR test charges extra if applicable.
Solitaire Overseas operates under a rigorous quality management system. All ST35 / ST35.8 tubes undergo comprehensive inspection before dispatch:
| Test / Certificate | Standard / Scope |
|---|---|
| Material Test Report | EN 10204 3.1; EN 10204 3.2 third-party witness on request |
| Chemical Analysis | Optical Emission Spectroscopy and PMI for heat traceability |
| Mechanical Testing | Tensile, yield, elongation and hardness |
| Hydrostatic / Pneumatic Test | Per DIN 2391, DIN 17175 or customer specification |
| Non-Destructive Testing | Ultrasonic, eddy current and magnetic particle inspection |
| Dimensional Inspection | OD, wall thickness, straightness and ovality per DIN tolerances |
| IBR Certification | Available for boiler-service tubes |
| Third-Party Inspection | SGS, Bureau Veritas, TÜV and Lloyd's Register on request |
| Heat / Lot Traceability | Full heat number traceability maintained on all shipments |
ST35 DIN 2391 is a precision cold-drawn tube for hydraulic, pneumatic, and mechanical applications. ST35.8 DIN 17175 is a seamless tube engineered for boiler, heat exchanger, and elevated-temperature pressure service.
DIN 17175 ST35.8 is approximately equivalent to ASME SA210 Grade A-1. Its current EN equivalent is P235GH under EN 10216-2. Always verify project-standard requirements before substitution.
Seamless tubes are available from 4 mm to 219 mm OD with wall thicknesses from 0.5 mm to 20 mm. Custom diameters, wall thicknesses, and lengths can be supplied.
We supply BK, BKW, BKS, GBK, and NBK delivery conditions. Specify the required condition when requesting a quotation.
EN 10204 3.1 Mill Test Certificates are standard. EN 10204 3.2, IBR, SGS, BV, TÜV, Lloyd's Register, hydrostatic reports, chemical analysis, and heat traceability are available as required.
Allowable temperature depends on pressure, wall thickness, design life, and the governing code. DIN 17175 stress tables commonly cover elevated-temperature service around 450-500°C; consult the applicable design code before specifying a maximum operating temperature.
Yes. GBK soft-annealed tubes offer high ductility and are suited to deep drawing, hydroforming, and severe cold-bending operations.
ST35.8 tubes can be supplied with IBR approval documentation for applicable boiler and pressure-system projects in India. State the IBR requirement at the enquiry stage.
There is no fixed minimum order quantity for many stock lines. Availability and lead time depend on the required size, condition, and certification scope.
Yes. Inspection by SGS, Bureau Veritas, TÜV, and Lloyd's Register can be arranged with complete traceability and testing documentation.
Send your OD, wall thickness, length, delivery condition, and quantity for availability and pricing within 24 hours.
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