JIS G3429 Seamless Steel Tube Specification

Boiler Pipe seamless steel pipe SMLS Pipe

JIS G3429 Seamless Steel Tube

JIS G3429 is a Japanese industrial standard for seamless steel pipes for high-pressure gas containers.

This standard mainly specifies the technical requirements for seamless gas pipes for high-pressure applications, and contains specifications for 5 different grades.

Among them, STH12 is one of the most commonly used manganese steel grades in this standard. This medium-low carbon chromium-molybdenum steel has high strength at high temperatures and excellent creep resistance. It is specially designed to withstand high-pressure environments. It is mainly used in high-pressure gas containers and pipeline systems, such as liquefied petroleum gas (LPG) storage tanks.

Get A Free Quote

Specification

Standard	JIS G3429
Procedure	SMLS
Dimensions	21.3mm – 114.3mm
	3/4″ – 4″
	DN20 – DN100
Thickness	2mm – 40mm
Thickness	SCH 5S -SCH XXS
Unit Length	5 – 16 mtrs
Steel Grade	JIS G 3429 STH11 JIS G 3429 STH21
Steel Grade	JIS G 3429 STH12 JIS G 3429 STH22
Surface Coating	Varnishing, Black, Oiling, Hot Dip Galvanizing
End Type	Square cut, Bevelled, Threaded, Grooved
Joint Method	Fitting, Flange, Coupling, Clamp, Pipe Shoulder, Welding
Pipe Machining	Welding, Bending, Hole Drilling, Punching, Swaging, Tapering, Flaring, Expanding

Dimension

Dimensions

Dimensions shall be conform to the agreement between the purchaser and the manufacturer.

Chemical Requirement

Symbol of Grade	C	Si	Mn	P	S	Ni	Cr	Mo
STH11	0.5 max.	0.10 to 0.35	0.18 max.	0.035 max.	0.035 max.	a)	a)	a)
STH12	0.30 to 0.41	0.10 to 0.35	1.35 to 1.70	0.030 max.	0.030 max.	a)	a)	a)
STH21	0.25 to 0.35	0.15 to 0.35	0.40 to 0.90	0.030 max.	0.030 max.	0.25 max.	0.80 to 1.20	0.15 to 0.30
STH22	0.33 to 0.38	0.15 to 0.35	0.40 to 0.90	0.030 max.	0.030 max.	0.25 max.	0.80 to 1.20	0.15 to 0.30
STH31	0.35 to 0.40	0.10 to 0.50	1.20 to 1.50	0.030 max.	0.030 max.	0.50 to 1.00	0.30 to 0.60	0.15 to 0.25
Alloy elements other than those in this table may be added as required. Note a) Ni,Cr or Mo, when added as necessary，shall not be added to such a degree that the specified values of another grade are satisfied，marking the grade no longer discernible.

Mechanical Requirement

Mechanical Properties
Hydraulic test characteristics：
Tubes shall withstand the applied hydraulic pressure of 5 MPa without leakage.
The purchaser may designate the pressure of over 5 MPa.
Nondestructive examination characteristic
Tubes shall be examined by either of ultrasonic flaw detection or eddy current flaw detection，and there shall be no signal at least equal to that from the artificial defects of the reference test piece of working sensitivity division UD of JIS G 0582 or working sensitivity division EY of JIS G 0583. Other nondestructive examinations in place of the ultrasonic flaw detection or eddy current flaw detection may be applied upon the agreement between the purchaser and the manufacturer.