STK540

JIS G3444 STK540 carbon steel tubes are utilized in civil engineering and architectural structures such as steel towers, footing piles, foundation piles, landslide suppression piles, and so on. This standard belongs to the Japanese Industrial Standard.

Why choose tuspipe?

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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Manufacturing Method of JIS G3444 Grade STK540 Steel Pipe

The manufacturing method shall be as follows:

Tubes shall be manufactured by a combination of the tube manufacturing method and the finishing method shown in table 1. If necessary, appropriate heat treatment may be applied to the tube.

Tubes may be made using coated steel sheet or coated steel strip if so, requested by the purchaser.

Bevel end finishing may be applied under the purchaser’s specification, in which case the shape shall be based on the agreement between the manufacturer and the purchaser.

JIS G3444 STK540 Grade Symbol and Symbol of Manufacturing Method

Symbol of Grade	Symbol of Manufacturing Method		Marking of Symbol of Manufacturing Method
	Tube manufacturing	Finishing method
STK540	Seamless: S Electric resistance Butt welded: B Automatic arc welded: A	Hot finished: H Cold finished: C As electric resistance welded: G	As given in clause 11 b)

JIS G3444 STK 540 Chemical Composition

Symbol of Grade	C	Si	Mn	P	S
STK540	0.23 max.	0.55 max.	1.50 max.	0.040 max.	0.040 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.

JIS G3444 Grade STK 540 Mechanical Properties

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.
STK540	540 min.	390 min.	540 min.	7/8 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.

JIS G3444 Grade STK540 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 the tube axis direction	Tube axis direction	Perpendicular to the tube axis direction
STK540	23	23	18	21	17
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 stk540

- 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 STK540

Each tube having passed the inspection shall be marked with the following items on each STK540 tube. For tubes of 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
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
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.
Manufacturer’s name or its abbreviation
Symbol indicating the type of coating (in the case of using coated steel sheet or coated steel strip). Abbreviation of symbol shall be as agreed between the manufacturer and the purchaser.