Grades · Q355B
Q355B Structural Steel Pipe
The current GB designation that replaced Q345B. Same structural role and near-identical mechanical envelope — if your drawing calls for either, we can usually supply from the same stock, confirmed against the mill certificate.
31
Sizes in stock
Φ146–426
OD range (mm)
20–75
Wall range (mm)
GB/T 1591-2018
Standard
International equivalents
| Chinese standard | GB/T 1591-2018 |
|---|---|
| Closest equivalent | EN S355JR |
| Also comparable | ASTM A572 Gr.50 |
Typical properties
| Yield strength | ≥ 355 MPa (≤16mm section, standard minimum) |
|---|---|
| Tensile strength | 470–630 MPa |
| Impact | Grade B: 20 °C; C/D/E to −20 °C / −40 °C |
Typical applications
- General structural steelwork
- Machine bases and welded frames
- Pressure-bearing structural sections
Delivery conditions
The delivery condition changes the material more than most buyers expect. Tell us what the part has to do and we will recommend one.
Hot rolledNormalizedQuenched & tempered
Q355B sizes on the ground
31 combinations, updated 2026-08-22. Quantities turn over daily — confirm availability when you inquire.
| OD × Wall (mm) | OD (in) |
|---|---|
| Φ146 × 20 | 5.75″ |
| Φ146 × 27 | 5.75″ |
| Φ152 × 30 | 5.98″ |
| Φ152 × 42 | 5.98″ |
| Φ159 × 26 | 6.26″ |
| Φ159 × 28 | 6.26″ |
| Φ159 × 30 | 6.26″ |
| Φ159 × 32 | 6.26″ |
| Φ159 × 40 | 6.26″ |
| Φ194 × 28 | 7.64″ |
| Φ203 × 25 | 7.99″ |
| Φ219 × 20 | 8.62″ |
| Φ219 × 25 | 8.62″ |
| Φ245 × 25 | 9.65″ |
| Φ245 × 35 | 9.65″ |
| Φ245 × 40 | 9.65″ |
| Φ254 × 22 | 10.00″ |
| Φ254 × 24.7 | 10.00″ |
| Φ254 × 26 | 10.00″ |
| Φ254 × 75 | 10.00″ |
| Φ273 × 25 | 10.75″ |
| Φ273 × 26 | 10.75″ |
| Φ273 × 27 | 10.75″ |
| Φ273 × 35 | 10.75″ |
| Φ273 × 40 | 10.75″ |
| Φ299 × 35 | 11.77″ |
| Φ299 × 40 | 11.77″ |
| Φ306 × 23 | 12.05″ |
| Φ310 × 50 | 12.20″ |
| Φ325 × 26 | 12.80″ |
| Φ426 × 45 | 16.77″ |
Q355B — common questions
- What is Q355B equivalent to?
- Q355B is closest to EN S355JR, ASTM A572 Gr.50. These are the standard comparisons used for sourcing; the mill certificate supplied with each shipment carries the actual chemistry and mechanical values for the heat.
- What sizes of Q355B do you stock?
- We currently hold 31 size combinations of Q355B, from Φ146mm to Φ426mm outside diameter with wall thickness from 20mm to 75mm.
- Can you supply Q355B heat treated?
- Yes. We supply Q355B in these delivery conditions: Hot rolled, Normalized, Quenched & tempered. Heat treatment is done in-house before shipment and process records with temperature curves ship with the goods.
- Can Q355B be cut to length before shipment?
- Yes. We saw-cut to fixed lengths with a typical tolerance of ±1–2mm and end squareness of ≤1mm/100mm, so the material can go straight onto your machine without a facing operation.
Need Q355B in a size that isn't listed?
Non-standard sizes are our specialty — and for repeat requirements we hold dedicated stock. Send your size list and we'll confirm within 24 hours.