Reviewing the old to gain new insights-003-Pressure ratings: PN versus CLASS. I certainly don’t believe in those rumors about unit conversions

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This post was last edited by wang_qia on 2016-12-28 at 11:00. Which standard specifies the definitions of DN, OD, and ID? Which standard specifies the definition of PN? Press [Ctrl+A] to highlight it: [GB/T 1047-2005 GB/T 1048-2005]. For PN series and class series, the nominal pressure is expressed as PN + [dimensionless number]. The dimensionless number does not represent a measured value and should not be used for calculation purposes, unless otherwise specified in relevant standards. =====Unprecedented ways of expressing nominal pressure ===== I’m a fancy divider line ===== 1. DIN series: 1-PN 2.5, 2-PN 6, 3-PN 10, 4-PN 16, 5-PN 25, 6-PN 40 (not 4.0) (PN40) (40 MPa), 7-PN 63, 8-PN… 2. ANSI series: 1-PN 20 (PN20) (20 MPa), 2-PN 50 (PN50), 3-PN…, 4-PN 50, 5-PN 260, 6-PN 420. 3. Custom series: 1. DIN series: 1-PN 2.5, 2-PN 6, 3-PN 10, 4-PN 16, 5-PN 25, 6-PN 40, 7-PN 63, 8-PN 100. 2. ANSI series: 1-PN 20, 2-PN 50, 3-PN 110, 4-PN 150, 5-PN 260, 6-PN 420. 4. Comparison table between ASME pound classes and national standard PN: HG/T 20592–20635-2009—Steel pipe flanges, gaskets and bolting: CL150-PN 20, CL300-PN 50, CL400…, CL600-PN…, CL800…, CL900-PN…, CL1000…, CL1200…, CL1500-PN 260, CL2500-PN 420, CL3000—Marsians… However, there is no corresponding PN value for these. A comparison table between ASME pound classes and national standard PN is often needed in design or procurement, especially when it comes to the American standard connection classes for flanges or valves such as CL1500. It’s useful to know what PN value corresponds to each pound class. What are the corresponding PN values in MPa for CL150, 300, 400, 600, 800, 900, 1200, 1500, 2500, and 3000? Standard HG/T 20615-97, Part 4: Nominal Pressure – The nominal pressure PN of flanges includes the following six grades: 2.0 MPa (Class 150), 5.0 MPa (Class 300), 11.0 MPa (Class 600), 15.0 MPa (Class 900), 26.0 MPa (Class 1500), and 42.0 MPa (Class 2500). Classes 800 and 1200 were derived through interpolation using the aforementioned ANSI standards; API 602 is likely the source for these classes. Classes 3000, 6000, 9000, and 2000 come from ANSI/ASME B16.11, which specifies requirements for socket-welded and threaded fittings, and they have no clear correspondence with the PN values for flanges used in pressure pipelines. The conversion between Psi and MPa: Psi is a unit of pressure, defined as pounds per square inch; 145 Psi equals 1 MPa (the value in Psi multiplied by 0.007 gives the corresponding value in MPa). The full English name for PSI is Pounds per square inch. P stands for pound, S stands for square, and I stands for inch. By converting all units to metric units, the conversion can be calculated: 1 bar ≈ 14.5 psi, 1 psi = 6.895 kPa = 0.06895 bar. Countries in Europe and the United States generally use psi as the unit of measurement. In China, we usually describe gas pressure in terms of “kilograms” (rather than “jin”), with the unit being “kg/cm^2”; one kilogram of pressure means one kilogram of force applied to one square centimeter. The unit commonly used abroad is “Psi”, specifically “lb/in2”, which means “pounds per square inch”. This unit is similar to the Fahrenheit scale (F). In addition, there are also pressure units such as Pa (Pascal, one newton per square meter), KPa, Mpa, Bar, millimeters of water column, and millimeters of mercury. 1 bar = 0.1 MPa = 100 KPa = 1.0197 kg/cm². 1 standard atmosphere (ATM) = 0.101325 MPa = 1.0333 bar. Since the differences between these units are quite small, and you’re not an engineer anyway. So, it can be remembered as follows: 1 bar = 1 standard atmosphere (ATM) = 1 kilogram per square centimeter = 100 kilopascals (KPa) = 0.1 megapascals (MPa). The conversion for psi is as follows: 1 standard atmosphere (atm) = 14.696 pounds per square inch 2 (psi). If you have the time and are willing to delve into it, take a look at this conversion table! Pressure conversion relationships: 1 bar = 10^5 Pa; 1 dyn/cm2 = 0.1 Pa; 1 Torr = 133.322 Pa; 1 mmHg = 133.322 Pa; 1 mmH2O = 9.80665 Pa; 1 engineering atmosphere = 98.0665 kPa; 1 kPa = 0.145 psi = 0.0102 kgf/cm2 = 0.0098 atm; 1 psi = 6.895 kPa = 0.0703 kgf/cm2 = 0.0689 bar = 0.068 atm; 1 physical atmosphere = 101.325 kPa = 14.696 psi = 1.0333 bar. There are two systems for valves: one is the “nominal pressure” system used in Germany (and also in 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 the U.S. temperature-pressure system, except for 150LB which uses 260 degrees as the reference, all other grades use 454 degrees as the reference. For a 25-grade carbon steel valve rated at 150 psi (1 MPa), the allowable stress at 260 degrees is 1 MPa; whereas at room temperature, the allowable stress is much higher, around 2.0 MPa. So, generally speaking, the nominal pressure rating corresponding to US standard 150LB is 2.0 MPa, while that corresponding to 300LB is 5.0 MPa, and so on. Therefore, the nominal pressure and temperature/pressure ratings cannot be arbitrarily changed using pressure conversion formulas for automatic control instruments