Structural hollow sections

Hybox® cold formed high-grade hollow sections

Hybox® is a cold formed, high-grade multi-purpose hollow section, offering trusted formability and toughness. It is batch-tested for your assurance and perfect for projects where you require guaranteed minimum strength and mechanical properties. It can be used in a wide range of structural and engineering applications, including all those where specific properties and compliance with design codes are required.

Hybox® fully complies with the European Standard for cold formed structural hollow sections, EN10219 S355 J2H and is used in a wide range of construction and mechanical related applications including wind bracing and machinery.



Tata Steel Hybox tube
Steigerwald Stadium Erfurt steel tube from Tata Steel
Stadium Zwickau, Tata Steel structural steel construction products
Tata Steel hybox tube in Steigerwald Stadium
Product specification

EN-Construction-Product-Hybox cold formed high-grade hollow sections-default

Hybox cold formed high-grade hollow sections
Specification details

EN-Construction-Product-Hybox cold formed high-grade hollow sections | Key product features

Key product features

Hybox® 355 - Cold formed structural hollow section

Key product features:

  • Excellent quality, made with steel from a high quality production process
  • Minimum strength of 355 N/mm2
  • Properties suitable for low temperature applications (27J @ -20°C)
  • Dimensional consistency and corner radius controlled
  • High levels of formability and, because the steel is fully-killed, excellent weldability
  • Suitable for applications demanding specific properties
  • Suitable for structural applications and fully compliant with design codes
  • Batch-tested to give the properties of the specific delivered material; full test certification supplied
  • Clearly marked as Hybox 355, with the reassurance of batch traceability
  • Specific technical support available
  • Excellent supply availability through approved stockholders
  • All Hybox 355 material is CE marked and is fully compliant with the Construction Products Regulation (CPR)
  • Suitable for galvanising

EN-Construction-Product-Hybox cold formed high-grade hollow sections | Mechanical properties

Mechanical properties
Yield strength  Tensile strength  Elongation % min  Impact strength  Carbon equivalent
ReH min N/mm2 Rm min N/mm2 L0 = 5,65 √S0  specimen 10mm x 10mm (CEV) max
T≤16mm T < 3mm 3mm≤T≤40mm T ≤ 40mm ºC J  
355 510-680 470 - 630 20 -20* 27 0.45

For section sizes D/T < 15 (circular) and (B+H)/ 2T < 12.5 (square/rectangle) min elongation is reduced by 2%. 

Chemical composition
% by mass

C Si Mn P S
0.22 0.55 1.60 0.030 0.030

Hybox® 355 is produced from fully killed steel - critical to formability and weldability.

EN-Construction-Product-Tubes-Hybox-Dimensional tolerancesTSE

Dimensional tolerances

Dimensional capability

Hybox® 355 are available in sizes from 26.9 x 2.0 OD up to and including 508.0 x 16 OD in our circular hollow sections range and from 25 x 25 x 2.0 up to and including 300 x 300 x 12.5 and the equivalent rectangles in our rectangular hollow section range.

Hybox 355 is supplied with a test report 3.1 to EN10204. Standard lengths are 7.5 metres and 12.0 metres, with special mill lengths from 6 metres up to 18m available by arrangement.

Further details of specific size and grade combinations are available upon request.

Dimensional tolerances

Dimensional tolerances are in accordance with EN10219: Part 2

  Circular Square / Rectangular - Side length (mm) Square / Rectangular - Tolerance
Outside dimension (D B and H) ±1% with a min of ±0.50mm and a max of ±10mm H,B < 100
100 ≤ H,B ≤ 200
H, B > 200
±1% with a min of ±0.5mm

Thickness (T) For D ≤ 406.4mm
T ≤ 5mm ±10%
T > 5mm ±0.50mm
T ≤ 5mm
T > 5mm
Out of roundness (O) For D > 406.4mm
±10% with a max of ±2mm
2% for D/T < 100, where D/T ≥ 100 out of
roundness tolerance to be agreed
Concavity/ Convexity (independent
tolerance on outside dimensions)
- Max 0.8% with a min of 0.5mm
Squareness of side - 90º ± 1
External corner profile
(radius need not
be tangential to the sides)
EN10219: Part 2 Table 3
- T ≤ 6.0
6.0 < T ≤ 10.0
T > 10.0
1.6T to 2.4T
2.0T to 3.0T
2.4T to 3.6T
Twist (V) - 2mm plus 0.5mm/m length
Straightness 0.20% of total length & 3mm over any 1m length 0.15% of total length & 3mm over any 1m length
Mass (M) ±6% on individual lengths ±6% on individual lengths
Length -0 +50mm -0 +50mm