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Hebei haihao high pressure flange & pipe fitting group was established in 1982, located in Mengcun County the hometown of pipe fittings in China.

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JIS STPG38 Carbon Steel Seamless pipe for mechanical structural use

1. Scope This japanese Industrial Standard specifies the carbon steel pipes, hereinafter referred to as the “pipes”, used for pressure service at an approximate maximunn temperature of 350∩. The pipes for high pressure sevice shall be in accordance with JIS G 3455. Remarks 1. Pertaining to the electric-resistance welded steel tubes, when previously agreed upon wiht the manufacturer, the purchaser may designate the supplementary quality requirements Z 3 or Z 4 specified in Appendix, in addition to the items specified in this text. 2. The units and numerical values given in { } in this Standard are based on the international System of Units (SI) and are appended for informative referencw. Further, the traditional units accompanied by numerical values in this Standard shall be converted to the SI units and numerical values on Jan. 1, 1991. 2. Grade and Designation The pipe shall be classified into two grades and their letter symbols shall be as given in Table 1-1 or Table 1-2.


Letter symbol of grade (Informative reference)Traditional letter symbol of glade
STPG 370 STPG 38
STPG 410 STPG 42

4. Chemical Compostion The pipe shall be tested in accordance with 9.1 and the ladel analysis values obtained shall conform to Table 2-1 or Table 2-2.

Table 2

Letter symbol of grade Elongation %
C Si Mn P S
STPG 370 0.25 max. 0.35 max. 0.30 to 0.90 0.040 max. 0.040 max.
STPG 410 0.30 max. 0.35 max. 0.30 to 1.00 0.040 max. 0.040 max.

6. Hydrostatic Test of Nondestructive Test The pipe shall be tested in accordance with 9.5 and the resulting hydrostatic characteristic or nondestructive characteristic shall conform to either of the following two. The preference for which of them shall be left to the specification by the purchaser or to the discretion of the manufacturer. 6.1 Hydrostatic Test when a hydrostatic pressure specified in Attached Table 1-1 or 1-2 is applied, the pipe shall withstand it without leakage. 6.2 Nondestructive Test A nondestructive examination by either an ultrasonic test or an eddy current test shall be made on the pipe, and there shall be no signal greater than those produced by the artificial defects of the reference test block of division UD of the working sensitivity specified in JIS G 0582 or of divisionEY of the working sensitivity specified in JIS G 0583

Hydrostatic Test Pressure          Unit : kgf/Р{bar}

Schedule number Sch 10 20 30 40 60 80
Hydrostatic Test Pressure 20 {20} 35 {34} 50 {49} 60 {59} 90 {88} 120 {118}

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