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1. Scope This Japanese Industrial Standardard specifies the carbon steel tubes (hereafter referred to as "tubes") used for civil engineering, architecture, steel towers, scaffoldings, struts, piles for suppression of landslide(¹) and other structures.
Note (¹) The tubes used for piles for suppression of landslide are limited to seamless steel tubes and welded steel tubes of under 318.5 mm in outside diameter.
Remarks 1. This Standard shall not apply to the foundation piles of the welded steel tube of 318.5 mm or larger in outside diameter and piles for suppresion of landslide.
  
2. Grades and symbols
Tubes shall be classified into 5 grades, and their symbols shall be as given in Table 1.

Table 1   Grades and symbols

* World Standard Comparative Table

3. Chemical Composition
The tube shall be tested in accordance with 8.1 and the cast analysis values shall conform to Table 2.

Table 2  Chemical Composition

 Unit:%

Symbol of grade	C	Si	Mn	P	S
STK 290	-	-	-	0.050 max.	0.050 max.
STK 400	0.25 max.	-	-	0.040 max.	0.040 max.
STK 500	0.24 max.	0.35 max.	0.30~1.30	0.040 max.	0.040 max.
STK 490	0.18 max.	0.55 max.	1.50 max.	0.040 捞窍	0.040 max.
STK 540	0.23 max.	0.55 max.	1.50 max.	0.040 max.	0.040 max.

  Remark
1. Alloying elements other than those in the above table may be added, if necessary.
            2. For the tube of grade SPS 540 exceeding 12.5 mm in wall thickness, the chemical composition may be agreed upon by the purchaser and manufacturer.
            3. When the purchaser requires product analysis for the tube made of killed steel, the tolerances for the values given in the above table shall be as specified in Table 1.
(Tolerance on product analysis) in JIS G0321

4. Mechanical properties
 
5. Dimensions, mass and tolerances on dimensions

6. Apperance The apperance shall be as follows
  (1) The tube shall be practically straight, and both ends shall be at a right angle to the axis of the tube.
  (2) The tube shall be free from defects which are detrimental to practical use.
  (3) When particularly required by the purchaser, the surface finishing and plating of the tube shall be agreed upon by the purchaser and the manufacturer.

7. Method of manufacture The manufacturing method shall be as follows:
  (1) The tube shall be manufactured by seamless process, electric resistance welding, butt-welding or are-welding (spiral seam and straight seam) process.
  (2)The tube shall, as a rule, be as-manufactured witout heat treatment.

8. Test

9. Inspection
  
10.Marking

Each tube having passed the inspection shall be marked with the following items. The arrangement of items is not specified. However, smaller tubes and those especially specified by the purchaser may be bundled together to be marked for each bundle by suitable means.

(1) Symbol of grade
(2) Symbol which denotes method of manufacture (²)
(3) Dimensions
(4) Manufacturer's name or its identifying brand

      Note (²)   The symbol which denotes the method of manufacture shall be as follows,
However, the dash may be replaced by ablank.

                 Hot finished seamless steel tube                     :-S-H
                 Cold finished seamless steel tube                    :-S-C
                 Eletric resistance welded steel tube other than hot finished or cold finished steel tube:-E-G
                 Hot finished electric resistance welded steel tube    :-E-H
                 Cold finished electric resistance welded steel tube                :-E-C       
                Butt-welded steel tube                                                      :-B               
                 Arc-welded steel tube                                   :-A
               
11. Report 
The manufacturer shall submit a test report when previously requested by the purchaser.