Structural Celsius® 420

Celsius® 420

Celsius® 420 raising the standard with the next generation in ultimate hot-finished structural steel.

At Tata Steel, we’ve taken our leading Celsius® product range and made it even better. Celsius® 420 is the next generation in true hot-finished structural steel hollow sections. Through advances in our steel manufacturing capability, Celsius 420 offers a stronger steel grade of 420 N/mm2 that achieves up to 17% weight saving with less welding and enhanced aesthetic appeal.

Celsius 420 has been extensively trialled and tested to confirm its chemical composition & mechanical properties, so you have complete reassurance it will perform as specified.

Supported by full certification and batch testing, Celsius 420 ensures consistency and quality, combined with complete reliability and proven performance.

  • Normalised fine grain steel, so free of internal stresses and with a minimum strength of 420 N/mm2 – allowing the highest fabrication factors and enabling material cost savings and lighter structures
  • Available in a wide range of circular, square, rectangular and elliptical hollow sections
  • Tight corner radii, exceeding the standard - enhancing the product’s aesthetic appeal whilst avoiding the risk of brittle fracture which occurs in some cold formed products
  • Dimensional consistency, high levels of formability and, because the steel is fully-killed, excellent weldability
  • Certified as suitable for all structural applications, fully compliant with design codes and overcomes design risks associated with other forms of hollow sections
  • Certified as suitable for mechanical applications, especially those involving cyclic loading
  • Suitable for low temperature applications (40J @ -20°C)
  • Batch-tested to give the properties of the specific delivered material; full test certification supplied
  • Clearly marked as Celsius 420, with the reassurance of batch traceability
  • Full technical support available
  • Excellent supply availability through approved stockholders
  • All Celsius 420 material is CE marked and is fully compliant with the Construction Products Regulation (CPR)
  • Suitable for galvanising with guaranteed silicon content between 0.15 and 0.25%
  • Guaranteed CEV 0.45 max compared to standard of 0.5 CEV

High strength hot finished hollow sections suitable for all construction and mechanical applications. Celsius 420 is suitable for all internal and external applications to EN1993.

Celsius 420 hollow sections are supplied with a minimum yield strength of 420 N/mm2 and comply fully with the European Standard for hot finished structural hollow sections, EN10210:S420NH.

Yield strength
ReH min N/mm2;
Tensile strength
Rm N/mm2
Elongation % min
L0 = 5,65 √S0
Impact strength
10mm x 10mm
Carbon equivalent
(CEV) max
T ≤ 16mm ≤ 65mm T ºC J  
420 520-680 19 -20 40 0.45

Chemical composition % by mass

C maxSi maxMnP maxS maxNb maxV maAl total minTi maxCr maxNi maxMo maxCu maxN max
0.20 0.60 1.00
0.035 0.030 0.050 0.20 0.020 0.03 0.30 0.80 0.10 0.70 0.025

Celsius 420 is produced from fully-killed steel – critical to formability and weldability.

Inspection and testing
Celsius 420 hollow sections EN10210:S420NH are subject to specific inspection and testing and are supplied with an inspection certificate type 3.1 to EN10204.

Dimensional tolerances EN10210: Part 2

Outside dimension (D B and H) Circular ±1% with a min of ±0.5mm and maximum of ±10mm
Ellipticals ±1% with a min of ±0.5mm (The permitted tolerance
is twice the value for H<250)
±1% with a min of ±0.5mm
Thickness (T) -10%
Note: Positive deviation limited by mass tolerance
Note: Positive deviation limited by mass tolerance
Squareness of side - 90 degrees ±1 degree
External corner profile - 2T max at each corner*
(EN10210 has 3T max)
Concavity/convexity (x) - – ±1% of the side, measured independently
of the tolerance on the outside dimension
Twist (V) Ellipticals: 2mm plus 0.5mm/m max
(The permitted tolerance is twice the value for H<250)
2mm plus 0.5mm/m max
Section is placed on a flat surface with one end
held flat. At the other end the height difference of
the two lower corners is taken
Mass (M) ±6% on individual lengths ±6% on individual lengths
Straightness Maximum 0.2% of the total length & 3mm over every
1m length
Ellipticals: The permitted tolerance is twice the value for H<250
Maximum 0.2% of total length & 3mm over every
1m length
Length +150mm/-0mm +150mm/-0mm
Out-of-roundness (O) Circular 2% for hollow sections having a diameter to thickness
ratio not exceeding 100

* Unless shown otherwise

Design data for structural hollow sections

The essential aid for the design of steelwork

Comprehensive section property data is provided in this ‘blue book’  as well as tables of member resistances, which are given for both Celsius® and Hybox® structural hollow sections. This enables rapid selection of steel members in compression and bending. Tables are also provided for combined bending and compression, web resistance and shear resistance. This edition provides resistances in accordance with Eurocode 3 together with the relevant UK and German National Annexes, as well as resistances to BS 5950.

Click here to access our Design data / Blue Book.

Product Downloads

Please Register or  to gain access to locked downloads.


English We have automatically detected your language settings