Pipe & tube steel grades
7 pipe & tube steel grades from 3 designation systems, each with a full data sheet. Sorted by system; the yield and tensile values are the first line of each grade's mechanical table.
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ASTM / ASME
| Grade | No. | Type | C % | Yield MPa | Tensile MPa | Equivalents |
|---|---|---|---|---|---|---|
| A106 Grade B | K03006 | Seamless carbon steel pipe for high-temperature service | ≤ 0.3 | 205 | ≥ 330 | A53 Gr. B (Type S), API 5L Gr. B, P235GH / P265GH |
| A333 Grade 6 | K03006 | Carbon steel pipe for low-temperature service, impact tested at −45 °C | ≤ 0.3 | 240 | 415 | a106-b, a53-b, P275NL1 |
| A53 Grade B | K03005 | Pipe steel for general and structural service, welded or seamless | ≤ 0.3 | 240 | 415 | a106-b, p235tr1, s195t |
EN (European)
| Grade | No. | Type | C % | Yield MPa | Tensile MPa | Equivalents |
|---|---|---|---|---|---|---|
| E355 | 1.0580 | Seamless cold drawn precision tube | ≤ 0.22 | ≥ 355 | 490–630 | st52, s355j2, p235tr1 |
| P235TR1 | 1.0254 | Welded non-alloy pressure tube, room-temperature properties | ≤ 0.16 | 235 | 360–500 | a53-b, a106-b, p235gh |
| S195T | 1.0026 | Non-alloy steel for welded and threaded tubes (water, gas, sprinkler, GI pipe) | ≤ 0.2 | 195 | 320–520 | A53 Grade A (Type E/F), Ст2сп / Ст3сп (GOST 3262), SGP (JIS G3452) |
API (line pipe)
| Grade | No. | Type | C % | Yield MPa | Tensile MPa | Equivalents |
|---|---|---|---|---|---|---|
| L360 / X52 | — | Line pipe steel, 360 MPa minimum yield | ≤ 0.24 | 360 | 460 | L360NB / L360MB, s355j2h, a106-b |
The grade depends on what the pipe carries
Pipe steels split by service. Structural hollow sections to EN 10219 and EN 10210 use S235 to S460 structural grades and are designed on yield. Pressure pipe to EN 10216 and EN 10217 uses P235TR and the GH family, with elevated-temperature properties. Line pipe to API 5L uses X42 to X70, where the number is the yield in thousands of psi. Water and gas pipe to EN 10255 is specified by dimension and coating more than by grade.
The same physical tube can sit in any of these standards. What differs is what has been tested and guaranteed.
Welded or seamless is a standards decision
EN 10219 (cold-formed welded) and EN 10210 (hot-finished, welded or seamless) look similar and behave differently. Hot-finished sections have tighter corner radii, lower residual stress and better toughness; cold-formed sections are cheaper and dimensionally more consistent.
For pressure service the distinction is written into the code: some applications accept welded pipe only with specific non-destructive testing, and some require seamless outright. The seam is not a weakness in itself — an ERW weld is tested — but the code decides, not the buyer.
Nominal bore is a name, not a dimension
A 2 inch pipe measures 60.3 mm on the outside. The outside diameter was frozen so that threads and fittings keep fitting while wall thicknesses changed with the schedule; the inch designation survived as a label.
Order by outside diameter × wall thickness and treat NB, DN and the inch figure as names. DN 50, 2 inch and 60.3 mm all mean the same pipe, and only the last one is a measurement.
Frequently asked questions
What is the difference between EN 10219 and EN 10210?
EN 10219 covers cold-formed welded hollow sections; EN 10210 covers hot-finished ones, welded or seamless. Hot-finished has tighter corner radii, lower residual stress and better low-temperature toughness; cold-formed is cheaper and dimensionally tighter.
Why is a 2 inch pipe 60.3 mm?
Nominal bore is an inherited label rather than a measurement. The outside diameter was standardised so that threads and fittings stay interchangeable, while the wall thickness varies by schedule inside that fixed outside diameter.
What does X52 mean in API 5L?
A minimum yield strength of 52,000 psi, roughly 359 MPa. The API line-pipe grades are named by yield in thousands of pounds per square inch — X42, X52, X60, X65, X70.
Which standard covers water pipe?
EN 10255 for threadable steel tube used in water, gas and general service, usually galvanized. It is specified by dimension series — light, medium and heavy — rather than by a strength grade.
Is seamless pipe stronger than welded?
Not inherently. A tested ERW weld develops the strength of the parent metal. Seamless is specified where a code demands it, where the wall is thick, or where the wider wall tolerance of seamless is acceptable in exchange for having no seam to inspect.