JIS G3458 Alloy Steel Pipes

 

JIS G3458 Alloy Steel Pipes

 

JIS G3458 alloy steel pipe is mainly used for piping at elevated temperatures. Outside diameter of these pipe is from 10.5mm up to 660.4mm. ( nominal diameter 6A or 1/8B to 650A or 26B)

 

Details of JIS G3458 alloy steel pipes

Product name: JIS G3458 alloy steel pipes

Classification and grade:

molybdenum steel pipe--STPA12

chromium molybdenum steel pipe--STPA20, STPA22, STPA23, STPA24, STPA25, STPA26

Manufacturing method: by seamless

Finishing method: hot finished, cold finished

 

 

Heat treatment

The JIS G3458 alloy steel pipe shall be given a heat treatment specified as below. Other heat treatment may be applied upon agreement between the buyer and seller.

Symbol of grade	Heat treatment
STPA12	Low temperature annealing, isothermal annealing, full annealing, normalizing or normalizing followed by tempering
STPA20	Low temperature annealing, isothermal annealing, full annealing or normalizing followed by tempering
STPA22
STPA23	Isothermal annealing, full annealing or normalizing followeed by tempering
STPA24
STPA25
STPA26
The tempering temperature for grades STPA23, STPA24, STPA25 and ATPA26 shall be 650℃ or higher

 

Hydrostatic test

We will carry out the hydrostatic test for each pipe body as specified. when the purchaser specifies test pressure, the pressure shall be applied as the minimum hydraulicc test pressure, and the pipes shall withstand it without leakage. If the pressure value specified by the purchaser is greater than the value P calculated by the follow formula or than 20 MPa, the test pressure to be applied shall be as agreed between the purchaser and manufacurer.

The specified test pressure shall be rounded off to the nearest 0.5 MPa for value lower than 10 MPa and the nearest 1 MPa for values 10 MPa or higher. Values calculated by the given formula shall be rounded off to the nearest 0.5MPa or 1MPa in the same manner. The formula as follows,

 

P=2st/D

 

P: test pressure (MPa)

t: wall thickness of pipe (mm)

D: outside diameter of pipe (mm)

s: 60% of the specified minimum value of yield point or proof stress

 

Minimum hydraulic test pressure MPa

Nominal thickness	Schedule number: Sch
	10	20	30	40	60	80	100	120	140	160
Minimum hydraulic test pressure	2.0	3.5	5.0	6.0	9.0	12	15	18	20	20

 

Non-destructive test

Pipes shall be tested by either the ultrasonic examination or the eddy current examination, and their non-destructive test characteristics. However, other non-destructive tests specified in JIS may replace these test upon agreement between the purchaser and the manufacturer, in which case, the criteria for judgement shall be at least equal to those for the ultrasonic examination or eddy current examination.

 

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