JIS G3444

JIS G3444

JIS G3444 is a Japanese Industrial Standard that describes carbon steel tubes (hereinafter referred to as “tubes”) for civil engineering and architectural applications such as steel towers, scaffoldings, footing piles, foundation piles, and landslide suppression piles. This Standard, however, is only applicable in an application for foundation piles to welded steel tubes with an outer diameter of less than 318.5 mm, and in an application for landslide suppression piles to seamless steel tubes and welded steel tubes with an outside diameter of less than 318.5 mm (1).

NOTE:

(1) The dimensional range covered by this Standard is generally outside diameter of 21.7mm to 1 016.0 mm.

(2) For foundation piles and piles for landslide suppression of welded steel tube of outside diameter 318.5 mm or larger, JIS A 5525 applies.

PRODUCT FEATURES

Steel Grade of JIS G3444 Pipes

Classification and Symbols of JIS G3444 Steel Pipes

The JIS G3444 tubes shall be classified into five grades, and symbols of grade and manufacturing method shall be as given in bellow.

Symbol of Grade

Symbol of manufacturing method

Tube manufacturing method

Finishing method

Marking

STK 290

Seamless: S

Electric resistance welding: E

Butt welded: B

Automatic arc welded: A

Hot finished: H

Cold finished: C

As electric resistance welded: G

As given in clause 11 b).

STK 400

STK 490

STK 500

STK 540

1.       Dimensions shall be marked by outside diameter and wall thickness.

2.       Manufacturer’s name or its identifying brand

3.       Symbol indicating the type of coating (in the case of using coated steel sheet or coated steel strip). This abbreviation for this symbol shall be as agreed between the purchaser and the manufacturer.

Chemical Composition of JIS G3444

The tubes must be examined in accordance with 9.1 at standard, and the heat analysis results must match those in the table below. When the customer requests a product analysis, the tube must be tested in accordance with 9.1 and the acquired product analysis values must meet the criteria in Table within the tolerances specified in Table of JIS G 0321.

Symbol of grade

C

Si

Mn

P

S

JIS G3444 STK 290

0.050max.

0.050max.

JIS G3444 STK 400

0.25max.

0.040max.

0.040max.

JIS G3444 STK 490

0.18max.

0.55max.

1.65max.

0.035max.

0.035max.

JIS G3444 STK 500

0.24max.

0.35max.

0.30 to 1.30

0.040max.

0.040max.

JIS G3444 STK 540

0.23max.

0.55max.

1.50max.

0.040max.

0.040max.

Notes:

1.       If necessary, other alloy elements than those given in this table may be added.

2.       For STK540, the chemical composition of tubes of wall thickness over 12.5 mm may be agreed between the purchaser and the manufacturer.

Mechanical Properties of JIS G3444

Symbol of grade

Tensile strength

N/mm2

Yield point or proof stress

N/mm2

Weld Tensile

N/mm2

Flattening

resistance

strength

Bendability

 

Distance between flat plates (H)

Bending angle, a)

Inside radius

Applicable outside diameter

All outside

diameters

All outside

diameters

All outside

diameters

All outside

diameters

50 mm or under

JIS G3444 STK 290

290 min.

290 min.

2/3D

90°

6D

JIS G3444 STK 400

400 min.

235 min.

400 min.

2/3D

90°

6D

JIS G3444 STK 490

490 min.

315 min.

490 min.

7/8D

90°

6D

JIS G3444 STK 500

500 min.

355 min.

500 min.

7/8D

90°

6D

JIS G3444 STK 540

540 min.

390 min.

540 min.

7/8D

90°

6D

NOTE 1    In this table, D stands for the outside diameter of tube.

NOTE 2    1 N/mm 2 = 1 MPa

Note a)    The bending angle shall be measured from the starting point of the bend.

Manufacturing Method of JIS G3444

The manufacturing method of JIS G3444 shall be as follows:

  1. The tubes must be created using a combination of the tube production technique and the finishing method shown in Table 1. Tubes may be treated with suitable heat treatment if necessary.
  2. If the client requests it, the tubes can be fabricated from coated steel sheets and coated steel strips. The type of coating and coating mass used in this circumstance should be in line with Annex A.
  3. Unless otherwise indicated, the tubes must have plane ends. If the consumer requests bevel end finishing, the shape of the bevel end must be agreed upon between the purchaser and the maker.

Markings of JIS G3444

Each tube that has passed inspection must be labeled with the following information. Marking may be applied to each bundle of tubes using a suitable manner for tubes with lower outer diameters or where the customer has made a particular request. The arrangement of the markers is not defined. Part of the items may be omitted if the customer approves, as long as the goods can still be identified.

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