Nippon Steel & Sumikin Pipe provides the carbon steel tubes for building structures described below.

Applications and Features

Carbon steel tubes for building structures are mainly used in building structures.

When used for building applications, they are required to have excellent weldability and the property of being resistant to destruction during an earthquake.

Chemical Composition and Mechanical Properties

Notes:

1. Alloying elements besides those given here may be added as necessary.
2. The specifications for N are tubes as cold formed. Also, when AI or other elements that fix N are added and free nitrogen is no more than 0.006%, the total nitrogen included may be up to 0.009%. In this case, the method for determining the amount of free nitrogen is to subtract the quantitative value of nitride from the quantitative value of total nitrogen.
3. Carbon equivalent is calculated based on the following formula:
   Carbon equivalent (%) = C + Mn/6 + Si/24 + Ni/40 + Cr/5 + Mo/4 + V/14
4. On agreement between the receiving and delivering parties, weld crack sensitivity composition may be applied instead of carbon equivalent. Calculation of weld crack sensitivity composition uses cast analysis and is based on the following formula:
   Weld crack sensitivity composition (%) = C + Si/30 + Mn/20 + Cu/20 + Ni/60 + Cr/20 + Mo/15 + V/10 + 5B
5. When performing the tensile test with the No. 12 test piece on tubes with a wall thickness of less than 8 mm, the minimum elongation value shall be the value obtained by subtracting 1.5% from the given elongation value for each 1 mm reduction in thickness and rounding off to an integer in accordance with JIS Z8401.
6. Charpy absorbed energy applies to tubes with a minimum outer diameter of 400 mm and a wall thickness greater than 12 mm, and is the average for three test pieces.

Dimensional Tolerances

Outer Diameter Tolerances

Notes:

1. The outer diameter tolerances for the ends of tubes with an outer diameter greater than 350 mm shall be ±0.5%.
2. The method for measuring the outer diameter of tubes with an outer diameter greater than 350 mm can be based on circumference.

Wall Thickness Tolerances

Production Range

Notes: Please consult us about sizes other than those given above.

Standard Dimensions / Mass and Cross-sectional Performance

Carbon Steel Tubes for General Structures (JIS G3444 STK) / Carbon Steel Tubes for Building Structures (JIS G3475 STKN) /