JIS G3466 Carbon steel Square for general structural purposes (JIS G 3466 / JISG3466)

1. Scope

This Japanese Industrial Standard specified the carbon steel square pipes, hereinafter referred to as the "square tubes", used for civil engineering architecture and other structures.

The units and numerical values given in { }in this Standard are based on the International System of Units (SI) and are appended for informative refernce.
Further, the traditional units accompanied by nimerical values in this Standard shall be converted, January 1, 1991, to the SI units and numerical values.

2. Grade and Designation
Square tubes shall be classified into 2 grades, and their designation shall be as given in Table 1

Table 1 Designation of Grade

Designarion of grade

Former grade

STKR 400
STKR 490


* World Standard Comparative Table *
















D 3568

SPSR 400 (new)
SPSR?41 ??


Gr B


STKR 400 (new)
STKR ?41?



EN 10025


SPSR 490 (new)
SPSR?50 ??

Gr C

STKR 490 (new)
STKR ?50 ??




Gr A
Gr D




3. Method of Manufacture

? (1) Square tubes shall be manufactured by forming welded steel tubes (by means of electric resistance welding. forging welding or automatic arc welding) or seamless steel tubes into square section, or manufactured by forming a steel sheet in coil into square section or into one pair of channel section followed by a continuous electric resistance welding or automatic arc welding process.
?? (2) Square tubes shall be furnished as manufactured condition and, as a rule,
not heat-treated.

4. Chemical Composition
The pipe shall be tested in accordance with 8.1 and the resulting ladle analysis values shall conform to Table 2

Table 2.
Chemical Composition

Desgination of grade

Chemical Composition






STKR 400

0.25 max.



0.040 max.

0.040 max.

STKR 490

0.18 max.

0.55 max.

1.50 max.

0.040 max.

0.040 max.

When a pipe is made from killed steel and the purchaser requires product analysis, the tolerances on the values given in the above table shall be as specified in Table 1 in JIS G0321.

. Mechanical Properties
??5.1 TensileStrength, Yield Point or Proof Stress and Elongation
The tube shall be tested in accordance with 8.2 and the resulting tensile strength, yield point or proof stress and elongation shall conform to Table 3.

Table 3. Mechanical Properties

Designation of grade


Tensile strength

Yield point or proof stress

Elongation %
(No.5 test piece)

STKR 400

400 {41} min.

245 {25} min.

23 min.

STKR 490

490 {50} min.

325 {33} min.

23 min.


1. When the tube under 8 mm in thickness is subjected to tensile test, the minimum value of elongation shall be calculated by subtracting 1.5 % from the value of elongation given in Table 3 for each decrease of 1 mm and rounding off the result to a whole number according to JIS Z 8401.
2. When a tensile test piece is to be taken from the welded steel square tube, one shall be taken from a seamless portion.
5.2 Bendability
For a square tubemanufactured by welding. a bending test on welded zone shall be made as required by the purchaser. In this case, the specified values, test method and sampling method shall be agreed upon by the purchaser and the manufacturer.

6. Apperance

?? 6.1 Square tubes shall be free from defects that are detrimental to practical use.
?? 6.2 The surface finishing of squre tubes and plating, if particularly required by the purchaser, shall be agreed upon between the purchaser and the manufacturer.

7. Dimensions, Mass and Dimensional Tolerances

8. Test

??8.1 Chemical Analysis
??? 8.1.1
General matters of chemical analysis and method of sampling specimens for analysis shall be in accordance with 3. in JIS G 0303.
8.1.2 Analytical Method
The analytical method shall be in accordance with one of the following Standards:
JIS G 1253 ,JIS G 1256, JIS G 1257, JIS G 1214
JIS G 1215, JIS G 1211, JIS G 1212, JIS G 1213
??? 8.2 Tensile Test
???? 8.2.1
The test piece shall be No. 5 test piece specified in JIS Z 2201 to be cut from the flat plate portion of the square tube along its longitudinal axis.
????? 8.2.2 Test Method
The test method shall be n accordance with JIS Z 2241.

9. Inspection

???(1) General matters of inspection shall be in accordance with JIS G 0303.
???? (2) The chemical composition, mechanical properties, apperance and dimensions for square tubes shall conform to the requirements specified in 3., 4., 5, and 6.
???? (3) The method of sampling test specimens and the number of test pieces for tensile test shall be as given in Table 5.

Table 5. Method of Sampling Test Specimens and Number of Test Piece

Length of longer side

Sampling method of test specimen and number of test piece

100mm or under

Take one test specimen from each 5000 m or its fraction of square tubes of the same grade and dimension, and from the specimen take one tensile test piece,

Over 100 mm up to and incl. 200 mm

To take one test specimen from each 2500 m or its fracion of square tubes of the same grade and dimension, and from the specimen take one tensile test piece.

Over 200mm

To take one test specimen from each 1250 m or its fracion of square tubes of the same grade and dimension, and from the specimen take one tensile test piece.

10. Reinspection

The tube is entitled to a retest in accordance with 4.4 in JIS G 0303 for final acceptance.


Each square tube having passed the inspection shall be legibly marked with the following items. The order of arranging the items is not specified.
However, smaller square tubes may be bundled together and be marked for each bundle by suitable means.

(1) Designation of grade
(2) Dimensions
(3) Manufacturer's name or its identifying brand
12. Report
The manufacturer shall submit a test report if previously required by the purchaser.

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