Carbon steel WPB (UNS K03006)
Carbon steel WPB (UNS K03006) — The workhorse grade for process, steam and utility piping.
| UNS number | K03006 |
| Material family | Carbon steel |
| Product specifications | ASTM A234 WPB (buttweld fittings), A106 Gr B / A53 Gr B (pipe) |
| Density (typical) | 7.85 g/cm³ (7850 kg/m³) |
| Weight of 6" Sch 40 pipe | 28.26 kg/m |
Specifications by product form
One alloy is ordered under different ASTM/ASME numbers depending on form: forged flanges and fittings, wrought buttweld fittings, and pipe or tube. For Carbon steel WPB the usual specifications are ASTM A234 WPB (buttweld fittings), A106 Gr B / A53 Gr B (pipe). Quote both the specification and the UNS number on purchase orders to avoid ambiguity.
Chemical and mechanical limits differ between these specifications — always check the edition of the standard named on your order and the mill test certificate.
Chemical composition & mechanical properties
| Property | Carbon steel A106 Gr B | Carbon steel A234 WPB |
|---|---|---|
| Family | Carbon steel | Carbon steel |
| UNS | K03006 | K03006 |
| EN / W.Nr | 1.0425 P265GH | 1.0425 P265GH |
| Basis spec | ASTM A106 | ASTM A234 |
| Density g/cm³ | 7.85 | 7.85 |
| Chemical composition, % | ||
| C | 0.30 | 0.30 |
| Mn | 0.29–1.06 | 0.29–1.06 |
| P | 0.035 | 0.050 |
| S | 0.035 | 0.058 |
| Si | 0.10 min | 0.10 min |
| Cr | 0.40 | 0.40 |
| Ni | 0.40 | 0.40 |
| Mo | 0.15 | 0.15 |
| Cu | 0.40 | 0.40 |
| V | 0.08 | 0.08 |
| Mechanical properties (min) | ||
| Tensile strength | 415 MPa (60 ksi) | 415 MPa (60 ksi) |
| Yield strength (0.2%) | 240 MPa (35 ksi) | 240 MPa (35 ksi) |
| Elongation | – | 22% |
| Hardness (max) | – | 197 HB |
| PREN (min, from spec) | – | – |
Single values are maximums; ranges are min–max; "bal" = balance. Limits are typical of the basis specification for that product form — forgings, pipe and fittings specifications differ slightly. Always check the exact specification, edition and the mill test certificate.
Frequently asked questions
What is the UNS number of Carbon steel WPB?
K03006.
Which ASTM specifications cover Carbon steel WPB?
ASTM A234 WPB (buttweld fittings), A106 Gr B / A53 Gr B (pipe).
What is the density of Carbon steel WPB?
About 7.85 g/cm³ (7850 kg/m³), used for weight calculations.
Last updated 2026-11-02