S195T steel (1.0026): properties, composition, equivalents
S195T (1.0026) is the steel of EN 10255 water and gas pipe: 195 MPa yield, 320–520 MPa tensile, light/medium/heavy series (old BS 1387 Class A/B/C). Chemistry, wall tables, A53 Grade A and GOST 3262 equivalents.
What is S195T?
S195T is the only steel grade in EN 10255, the European standard for water, gas and sprinkler pipe that is screwed or welded — the pipe the trade calls GI pipe, black pipe, gas pipe or, by its old British name, BS 1387 Class B and C. The designation reads S (structural steel), 195 (minimum yield in MPa), T (tube). Werkstoff number 1.0026. Its strength is modest on purpose: the pipe is defined by its wall series — light (L), medium (M, old Class B) and heavy (H, old Class C) — and by a 50 bar leak test on every length, not by the steel.
Most S195T tube is high-frequency welded from S235JR-quality strip, hot-dip galvanized to EN 10240 A1 (≥ 55 µm zinc inside and out) and threaded BSPT to EN 10226-1 with a socket per bar. Sizes run DN 6 (⅛") to DN 150 (6"), 6 m long. Medium series is the potable-water and fire-sprinkler standard; heavy series adds wall for pressure and deeper threads.
ASTM A53 Grade A/B, GOST 3262 ВГП, JIS SGP and GB/T 3091 are the equivalents in their markets; where the tube is a structural member rather than a line, EN 10219 S235JRH is the right specification.
S195T chemical composition
| Element | Mass % | Note |
|---|---|---|
| C | ≤ 0.2 | |
| Mn | ≤ 1.4 | |
| P | ≤ 0.035 | |
| S | ≤ 0.03 |
Ladle analysis, EN 10255:2004 Table 1. Si is not limited; the steel is normally semi- or fully killed. Only one grade is specified in the standard — the series (L/M/H) defines the wall, not the steel.
S195T mechanical properties
| Thickness / condition | Yield strength ReH / Rp0.2 MPa (ksi) | Tensile strength Rm MPa (ksi) | Elongation A % | Hardness |
|---|---|---|---|---|
| All series, all sizes | 195 (28.3) | 320–520 (46.4–75.4) | 20 | ≈ 100–130 HB (typ.) |
| ASTM A53 Grade A (for comparison) | 205 (29.7) | 330 min (47.9 min) | — | — |
| ASTM A53 Grade B | 240 (34.8) | 415 min (60.2 min) | — | — |
EN 10255 Table 3: ReH ≥ 195 MPa, Rm 320–520 MPa, A ≥ 20 % (L0 = 5.65√S0). Leak-tightness test on every tube: hydrostatic at 50 bar (or eddy-current). Threadable series (M, H) must accept EN 10226-1 taper threads; flattening test to 2/3 D for welded tube.
S195T equivalent grades
| Grade | System | Match | Why / differences |
|---|---|---|---|
| A53 Grade A (Type E/F) | ASTM / ASME | Near | ASTM A53 Grade A: 205 MPa yield, 330 MPa tensile, welded or seamless, black or galvanized — the US water/gas pipe; Grade B (240/415) is stronger and usually what is stocked. |
| S235JR | EN (European) | Near | The strip from which most S195T tube is actually made; S235JR coil certified to EN 10255 requirements. |
| Q195 / Q235 (GB/T 3091) | GB/T (China) | Near | Chinese welded pipe for low-pressure liquid delivery on Q195–Q235 steel. |
| Ст2сп / Ст3сп (GOST 3262) | GOST (Russia/CIS) | Near | GOST 3262 water-gas pipe (ВГП, обыкновенная/усиленная) on Ст2–Ст3 steel: the CIS equivalent of medium/heavy series. |
| SGP (JIS G3452) | JIS (Japan) | Near | JIS G3452 carbon steel pipe for ordinary piping, Rm ≥ 290 MPa; galvanized SGP-W. |
| S235JRH | EN (European) | Functional | Structural hollow-section grade (EN 10219) with 235 MPa yield — the alternative when the pipe is a column or frame member, not a pressure line. |
| P235TR1 | EN (European) | Functional | EN 10217-1 pressure-purpose welded tube with specified elevated-temperature use; choose when the line is above 50 bar or a pressure code applies. |
Identical = same composition and mechanical limits within rounding. Near = one limit differs (e.g. carbon max or impact temperature). Functional = interchangeable for most uses after an engineering check. Full cross-reference for S195T →
Old and superseded designations
| Old name | Standard | Note |
|---|---|---|
| St33-2 / St 33 | DIN 17100 / DIN 1626 | German general steel used for DIN 2440/2441 gas pipe (mittelschwer / schwer). |
| BS 1387 steel (Class A/B/C) | BS 1387:1985 (withdrawn) | Class A = light, B = medium, C = heavy; the names survive in every GI-pipe market (Gulf, India, Africa). |
| Fe 330 | UNI 8863 | Italian threadable tube steel. |
Product forms and tolerance standards
Product forms: welded (HFI/ERW) tube DN 6–150 (½"–6"), light (L, L1, L2), medium (M) and heavy (H) series, seamless tube in the same series (rare), black, varnished or hot-dip galvanized per EN 10240 (A1–B3), plain, bevelled or threaded ends (EN 10226-1) with socket.
Dimensional tolerances: outside diameter: EN 10255 Table 2 (e.g. 33.7 +0.4/−0.5 mm for DN 25); wall thickness: medium/heavy −10 % (no plus tolerance stated; mass ±7.5 %); length: 4–8 m random, 6 m usual; exact length ±25 mm.
Key property values
S195T yield strength
≥ 195 MPa (28 ksi). Actual tube made from S235JR strip usually tests 240–300 MPa.
S195T tensile strength
320–520 MPa (46–75 ksi).
S195T elongation
≥ 20 % (L0 = 5.65√S0).
Working pressure
The standard guarantees a 50 bar hydrostatic test; typical working pressures used by installers are 16 bar (medium) and 25 bar (heavy) for cold water, subject to the joint and code. Threads are cut after galvanizing.
Wall series (examples)
DN 15 (½", 21.3 mm): L 2.0 · M 2.6 · H 3.2 mm. DN 25 (1", 33.7 mm): L 2.6 · M 3.2 · H 4.0 mm. DN 50 (2", 60.3 mm): L 2.9 · M 3.6 · H 4.5 mm. DN 100 (4", 114.3 mm): M 4.5 · H 5.4 mm. Galvanized mass adds about 3–4 %.
Weldability
Readily weldable (C ≤ 0.20, no preheat); bevelled ends 30° for butt welds. Galvanized tube must be ground back 20–30 mm from the joint, welded with fume extraction and repaired with zinc-rich paint — or joined by threads or grooved couplings to keep the coating intact.
Machining, forming and heat treatment
Threading BSPT/NPT, grooving (roll-groove for fire systems), cutting, drilling and bending (cold, radius ≥ 3 D with mandrel for medium series) are routine. Heavy series is preferred for deep threads and repeated re-threading.
Typical applications
- Potable-water and irrigation lines (medium series, galvanized)
- Fire-sprinkler and hydrant mains (grooved or threaded, red-painted)
- Gas and compressed-air lines at low pressure
- Scaffold tube 48.3 × 3.2 (also EN 39), fence posts, handrail
- Greenhouse, canopy and light structural frames (or S235JRH)
- Electrical conduit and cable protection
- Street-light and sign posts
Frequently asked questions
What is S195T?
The steel grade of EN 10255 tubes for water, gas and sprinkler lines: 195 MPa minimum yield, 320–520 MPa tensile, 20 % elongation, delivered in light, medium or heavy wall series, black or galvanized, threadable.
Is S195T the same as BS 1387 Class B / Class C?
Effectively yes. BS 1387 was withdrawn in favour of EN 10255; Class B corresponds to the medium series and Class C to the heavy series, with the same outside diameters and walls. "Class B GI pipe" in the Gulf or India means EN 10255 M galvanized.
What is the difference between medium and heavy series?
Wall thickness only: e.g. 1" pipe is 3.2 mm (medium) vs 4.0 mm (heavy). Heavy gives more pressure margin, deeper threads and longer corrosion life; the steel is the same S195T.
What is the ASTM equivalent of EN 10255 pipe?
ASTM A53 Grade A (205 MPa) is the direct equivalent; Grade B (240 MPa, 415 MPa tensile) is what most mills stock and dual-certify with EN 10255 where dimensions coincide (Schedule 40 walls are slightly different from medium series).
Can EN 10255 pipe be used for structures?
For handrail, fences and light frames yes; for designed structural members specify EN 10219 S235JRH or S355J2H (cold-formed hollow sections), which guarantee structural properties and tolerances rather than a leak test.
Related grades
Verified against EN 10255:2004+A1:2007; EN 10255:2004+A1:2007 Tables 1–3 (chemistry, dimensions, mechanical properties); EN 10240:1997 (zinc coatings on tubes); EN 10226-1 (pipe threads); ASTM A53/A53M-22. Last checked: September 2026.