JIS G3461 Carbon steel tubes for boiler and heat exchanger

JIS G3461 carbon steel tubes used for exchanging heat between the inside and outside of the tube, such as water tubes, smoke tubes, superheater tubes and air preheater tubes, etc. of boilers, and heat exchanger tubes, condenser tubes and catalyser tubes, etc. used in chemical and petroleum industries. It is not applicable to the steel tubes for fired heater and steel heat exchanger tubes for low temperature service.

JIS G3461 Carbon steel tubes dimensional and tolerances

outside diameters: 15- 150mm

wall thicknesses: 1-15mm

dimensional tolerances: +/-1% OD ; +/- 12% WT

JIS G3461 Carbon steel tubes Manufacturing method

The manufacturing method shall be as follows.

Tubes shall be manufactured from the killed steel and by a combination of the tube manufacturing method and the finishing method.

Seamless: S

Electric resistance welded: E

Hot-finished: H

Cold-finished: C

As electric resistance welded: G

JIS G3461 Carbon steel tubes Chemical composition

Symbol of grade	C	Si	Mn	P	S
STB340	0.18 max.	0.35 max.	0.30 to 0.60	0.035 max.	0.035 max.
STB410	0.32 max.	0.35 max.	0.30 to 0.80	0.035 max.	0.035 max.
STB510	0.25 max.	0.35 max.	1.00 to 1.50	0.035 max.	0.035 max.

JIS G3461 Carbon steel tubes Mechanical properties

Symbol of grade	Tensile strength	Yield point or proof stress	Elongation %
			Outside diameter
			Under 10 mm	10 mm or over to and excl. 20 mm	20 mm or over
			Test piece
			Test piece No. 11	Test piece No. 11	Test piece No. 11 Test piece No. 12
			Tensile test direction
	N/mm2	N/mm2	Parallel to tube axis	Parallel to tube axis	Parallel to tube axis
STB340	340 min.	175 min.	27 min.	30 min.	35 min.
STB410	410 min.	255 min.	17 min.	20 min.	25 min.
STB510	510 min.	295 min.	17 min.	20 min.	25 min.

JIS G3461 Carbon steel tubes Heat treatment

Normalizing

Low temperature annealing

full annealing

JIS G3461 Carbon steel tubes Appearance

The appearance shall be as follows.

1. a) Tubes shall be straight for practical purposes with both ends at right angles to thetube axis.
2. b) The inside and outside surfaces of tubes shall be finished smoothly and free from defects detrimental to use. For the electric resistance welded steel tubes, the convex on inside surface of the weld shall be 0.25 mm or under.
3. c) The surfaces of tubes may be repaired by grinding, machining or other methods, provided that the wall thickness after repair is within the specified tolerance on wall thickness.
4. d) The surface of the repaired part shall be smooth along the contour of the tube.

JIS G3461 Carbon steel tubes Tests and Inspection

Chemical analysis

Mechanical tests

Tensile test

Flattening test

Bend test

Hydrostatic test

Non-destructive test