STK290

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STK290

JIS G3444 STK 290 is one of the Japanese Industrial Standarded steel pipes primarily used for the following applications.

Creating pillars (eaves pillars, outside pillars, etc.)

Piles of steel pipe

The building’s pillars are made of STK materials. Steel columns are usually hidden by decorative materials, so steel tubes (columns) with lower cross-section properties than square steel tubes are not used. If, however, the steel column’s form is visible from the outside, utilize a cylindrical steel pipe.

Why choose tuspipe?

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Since 1998, Tianjin United Steel Pipe Co., Ltd (TUSPIPE) has been committed to supplying high-quality line pipes.

With over 500,000 tons annual production capacity, the company serves various fields and industries, such as oil & gas exploitation and transmission, ship & auto-building, water & electricity, environmental protection, mechanical engineering, infrastructure construction and etc.

TUSPIPE places a premium on product quality and rigorous product quality control. In order to maintain good product quality,  the company has established a Test & Inspection Center since 2004. With a series of state-of-the-art tests and inspection equipment, the test & inspection center is able to perform the tensile tests, hydro tests, impact tests, DWTT, etc.

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Chemical Composition of JIS G3444 STK290

Symbol of grade C Si Mn P S
STK290 0.050 max. 0.050 max.
Notes a) If necessary, alloying elements other than specified in this table may be added. b)For the tube of grade STK540 exceeding 12.5 mm in wall thickness, the chemical composition may be subject to the agreement between the purchaser and the manufacturer.

Mechanical Properties of JIS G3444 STK290

Symbol of Grade Tensile Strength N/mm² Yield Point of Proof Stress N/mm² Tensile Strength in Weld Zone N/mm² Flattening Bendability
Distance between Plates (H) Bend Angle Inside Radius
Applied outside diameter
All outside diameters All outside diameters All outside diameters All outside diameters 50 mm max.
STK290 290 min. 290 min. 2/3 D 90° 6 D
NOTE 1  D of this table is the outside diameter of the tubes. NOTE 2  1 N/mm²—1 MPa Note a) Standard of bend angle shall be the start point of bending.

STK290 Tensile Test Piece and the Minimum Value of Elongation

Symbol of grade Tube Manufacturing Method
Seamless and butt welded Electric resistance welded and automatic arc welded All manufacturing methods
Applied outside diameter
All outside diameters 350 mm Over 350 mm All outside diameters
Test Piece and Direction of Test Piece
No. 11 test piece No. 12 test piece No. 11 test piece No. 12 test piece No.5 test piece No.4 test piece
Tube axis direction Tube axis direction Perpendicular to tube axis direction Tube axis direction Perpendicular to tube axis direction
STK290 30 30 25 28 23
For the tubes of outside diameter 40 mm or under, the elongation value in this table shall not be applied. However, the test result for these tubes shall be recorded. Further, the elongation may be specified by agreement between the manufacturer and the purchaser.

Dimensional Tolerances of JIS G3444 STK290

- Outside Diameter Tolerance a)

Classification Outside Diameter b) Tolerances on Outside Diameter c) Applicable Division
Class 1 Under 50mm ± 0.5mm Applied when there is no specification. Applicable to hot-finished seamless steel tubes.
50mm or Over ± 1%
Class 2 Under 50mm ± 0.25mm Applied when there is a specification. Not applicable to hot-finished seamless steel tubes.
50mm or Over ± 0.5%
Notes a) For the local parts such as repaired parts if the wall thickness can be confirmed to be within the tolerance in the table below, the outside diameter tolerance of this table need not be applied.
b) The method for measuring the outside diameter of tubes exceeding 350mm in outside diameter may be determined by the circumferential length. The mutual conversion of outside diameter D and the circumferential length l shall be by the following formula:      D = l  / π Where D: outside diameter (mm)     l: circumferential length (mm)    π:3.1416
c) The tolerances on the outside diameter of ends of electric resistance welded and automatic arc welded steel tubes exceeding 350mm in outside diameter shall be ±0.5%。

- Wall Thickness Tolerance a)

Classification For Seamless Steel Tube For Other than Seamless Steel Tube Applicable Division
Wall Thickness Tolerance of Wall Thickness Wall Thickness Tolerance of Wall Thickness
Class 1 Under 4mm +0.6mm, -0.5mm Under 4mm +0.6mm, -0.5mm Applied when there is no specification. Applicable to hot-finished seamless steel tubes.
4mm or Over +15%, -12.5% 4mm or Over to and excl. 12mm +15%, -12.5%
12mm or Over +15%, -1.5mm
Class 2 Under 3mm ±0.3mm Under 3mm ± 0.3mm Applied when there is a specification. Not applicable to hot-finished seamless steel tubes.
3mm or Over ±10% 3mm or Over to and excl. 12mm ±10%
12mm or Over +10%,-1.2mm
Notes a) The tolerances on the wall thickness of tubes exceeding 1016.0 mm in outside diameter may be agreed upon between the manufacturer and the purchaser.

Marking of JIS G3444 Steel Grade STK290

Each tube having passed the inspection shall be marked with the following items on each STK290 tube. For tubes of a smaller outside diameter or when there is a special request by the purchaser, marking may be applied on a bundle. The order of arrangement of the markings is not specified. When approved by the purchaser, part of the items may be omitted.

  • Grade symbol
  • A symbol representing the manufacturing process. The following symbol should be used to indicate the production technique. However, a space may be used in place of the dash.
    1. As welded steel tube with electric resistance: -E-G
    2. Hot finished electric resistance welded steel tube:  -E-H
    3. Cold finished electric resistance welded steel tube:  -E-C
    4. Butt-welded steel tube:  -B
    5. Automatic arc welded steel tube:  -A
  • Measurements Outside diameter and wall thickness should be noted for dimensions.
  • The manufacturer’s name or an abbreviation of the manufacturer’s name
  • A symbol representing the coating kind (in the case of using coated steel sheet or coated steel strip). The maker and purchaser shall agree on the symbol’s abbreviation.
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