Round steel tube
Carbon steel tube
SGP (carbon steel pipe for ordinary piping)JIS G 3452For low-pressure water, air, steam and gas lines. It is the most common and the easiest to obtain, and is the place to start when you are unsure.STPG (carbon steel pipe for pressure service)ISO 9329-1 (JIS G 3454)For pressure piping up to 350 °C. Choose it where SGP does not stand the pressure.STS (carbon steel pipe for high-pressure service)ISO 9329-2 (JIS G 3455)For high-pressure piping up to 350 °C, where even STPG does not stand the pressure.STPT (carbon steel pipe for high-temperature service)ISO 9329-2 (JIS G 3456)For high-temperature piping above 350 °C.STPL (steel pipe for low-temperature service)ISO 9329-3 (JIS G 3460)For piping that drops below freezing. Choose it where brittle fracture at low temperature has to be avoided.STPA (alloy steel pipe for piping)ISO 9329-2 (JIS G 3458)For piping that is both hot and under high pressure. These are alloy steels such as molybdenum steel.STPY (arc-welded carbon steel pipe for piping)JIS G 3457For large-bore low-pressure piping. It is made by arc welding.STK (carbon steel tube for general structures)JIS G 3444For general structural members such as stands, scaffolding and towers. It is the place to start when you are unsure which structural pipe to use.STKM (carbon steel tube for machine structures)JIS G 3445For parts that need dimensional accuracy and strength, such as machine components and shafts.STKN (carbon steel tube for building structures)JIS G 3475For building structural members where seismic design is involved, such as columns.STB (carbon steel tube for boilers and heat exchangers)ISO 9329-2 (JIS G 3461)For the heat-transfer tubes of boilers and heat exchangers.TF (steel tube for fired heaters)JIS G 3467For the tubes inside fired heaters, as used in oil refining.
Stainless steel tube
SUS-TP (stainless steel pipe for piping)ISO 9330-6 (JIS G 3459)For piping that needs corrosion or heat resistance. This is the base standard for stainless steel piping.SUS-TPD (stainless steel pipe for ordinary piping)JIS G 3448For water supply, hot water and drainage lines. It is thinner and lighter than SUS_TP.SUS-TPY (large-diameter welded stainless steel pipe)ISO 9330-6 (JIS G 3468)For large-bore stainless steel piping. It is made by welding.SUS-A (stainless steel for building structures)JIS G 4321For building structural members that also have to resist corrosion.