The correspondence between pressure ratings PN and MPa, as well as pound ratings

It seems there’s quite a lot of information on this topic in the forum. You can definitely search first at http://bbs.hcbbs.com/forum.php?mod=viewthread&tid=1400441&highlight=%D1%B9%C1%A6%B5%C8%BC%B6. PN63 is equivalent to 6.3 Mpa, I guess. As for the standards, I’m not sure

I mainly want to know if there are any standards that can explain this relationship.

For the PN series, the number that follows it usually indicates the weight in kilograms; for the Class series, it’s directly given in LB. There is a corresponding value in Mpa as well – for example, 150LB corresponds to 2 Mpa, which is what is commonly referred to as 20 kilograms in engineering terms; this is PN20. PN63 corresponds to 6.3 Mpa, and 6.3 falls under the PN series. There is no corresponding value for this in the Class series (but it can certainly be converted). However, standards don’t go into such detail; as long as there is a corresponding value, that’s used; if not, the higher value is used instead. For instance, if the value is 6.3 Mpa, then in the Class series one would choose the next higher grade. 11 Mpa, which corresponds to 110 kilograms, can be used as a substitute. This is my personal understanding; this is how people usually handle things when looking for pipes and valves.

PN corresponds to kg/cm2, while MPa is 10 times PN. The common pressure grades used in the petrochemical industry are generally the European system (HG/T20592-2009) and the American system (HG/T20615-2009). The pressure grades corresponding to HG/T20592 are PN2.5, PN6, PN10, PN16, PN25, PN40, PN63, PN100, PN160, with the unit being kg/cm2. The pressure grades corresponding to HG/T20615 are: class150 (2.0 MPa), class300 (5.0 MPa), class600 (11.0 MPa), class900 (15.0 MPa), class1500 (26.0 MPa), class2500 (42.0 MPa). Class150 was previously also referred to as 150 lb (pounds).

I’ve learned it! ! ! ! ! ! ! ! ! ! ! ! ! ! ! !

PN is a code related to pressure, expressed in numerical form; it is a convenient round integer used as a reference. PN represents the pressure rating in MPa, adjusted to approximate normal temperature conditions, and it is the nominal pressure commonly used for valves in China. For control valves with carbon steel bodies, it refers to the maximum operating pressure permitted when used at temperatures below 200°C ； For cast iron valve bodies, it refers to the maximum operating pressure allowed when used at temperatures below 120°C ； For control valves with stainless steel valve bodies, it refers to the maximum operating pressure permitted when used at temperatures below 250°C. As the operating temperature increases, the pressure resistance of the valve body decreases. American standard valves use pounds as a unit to indicate their nominal pressure; this value is determined based on the melting temperature and pressure of a particular metal, in accordance with the ANSI B16.34 standard. The main reason why the pound rating and the nominal pressure do not correspond one-to-one is that they have different temperature references. We usually use software for calculations, but we also need to know how to use tables to check weight classes. Japan primarily uses the K value to indicate pressure ratings. Regarding the pressure of gases, in China we generally use its mass unit \"kilogram\" to describe it (instead of \"jin\”), with the unit being kg. The corresponding unit of pressure is “kg/cm2”; one kilogram of pressure means one kilogram of force applied to one square centimeter. Similarly, as is the case abroad, the common unit used to measure gas pressure is “psi”, which stands for “1 pound/inch2”, that is, “pounds per square inch”. The full English name for this unit is Pounds per square inch. But it is more common to refer directly to its unit of mass, namely pounds (LB.), and in fact this LB. is the pound-force mentioned earlier. By converting all units to metric units, the conversion can be calculated: 1 psi = 1 pound/inch2 ≈ 0.068 bar, 1 bar ≈ 14.5 psi ≈ 0.1 MPa. Regions such as Europe and the United States commonly use psi as the unit of measurement. For Class 600 and Class 1500, there are two different values corresponding to the European and American standards: 11 MPa (corresponding to the 600-pound class) is the value specified by the European system, as stated in \"ISO 7005-1-1992 Steel Flanges\" ； 10 MPa (corresponding to the 600-pound class) is specified in the American system, as outlined in ASME B16.5. Therefore, it cannot be said absolutely that a 600-pound class corresponds to 11 MPa or 10 MPa; the regulations vary depending on the system. There are mainly two systems for valves: one is the \"nominal pressure\" system, represented by Germany (including China), which is based on the allowable operating pressure at normal temperatures (100 degrees in China and 120 degrees in Germany). One is the \"temperature-pressure\" system represented by the United States, which is based on the allowable operating pressure at a certain temperature. In this system, except for 150LB which uses 260 degrees as the reference, all other levels use 454 degrees as the reference. For example, for a 25-grade carbon steel valve with a weight of 150 LB, the allowable stress at 260 degrees is 1 MPa; whereas at room temperature, the allowable stress is much higher than 1 MPa, around 2.0 MPa. Therefore, generally speaking, the nominal pressure class corresponding to US standard 150LB is 2.0 MPa, that corresponding to 300LB is 5.0 MPa, and so on. Therefore, the nominal pressure and temperature-pressure class cannot be arbitrarily converted using pressure conversion formulas.

The explanation is very detailed; I’ve learned a lot! ! !

Liking for the 7th floor; P; P; P

11 MPa (corresponding to the 600 pound class) is specified in the European system, as stated in ISO 7005-1-1992 Steel Flanges； 10 MPa (corresponding to 600 pound class) is the specification in the American system? Isn’t it reversed? In HG20615-2009, CLASS 600 corresponds to PN110, right?