Question regarding the method of indicating pipeline pressure ratings
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Hello, seniors! Regarding the method of indicating pipeline pressure grades, as I recall from textbooks and relevant engineering materials, the unit for Pg is kgf/cm2, while the unit for PN is MPa. In engineering, it is even not necessary to write the units; everyone knows that the units behind Pg and PN are kgf/cm2 and MPa respectively. For pipe components with a diameter of 100 and a pressure rating of 2.5 MPa, the designation is usually DN100 PN2.5; no one adds units such as mm or MPa after that. However, a few days ago it was discovered that in GB/T1048-2005, the pressure grades for the DIN series are indicated as PN10, PN16, PN25, PN40, PN63, PN100, replacing the previous values of PN1.0, PN1.6, PN2.5, PN4.0, PN6.3, PN10, etc. This is very confusing; on several occasions, procurement staff purchased materials with an engineering pressure of 1.0 MPa when what was needed was ones with a pressure of 10 MPa. Sometimes, discussions with foreign suppliers were filled with arguments and clarifications regarding this pressure level. I wonder if you have encountered this problem, and how you identified it, dealt with it, and prevented it. Thank you!
If the **standard GB/T1048-2005 for the method of marking pipe fittings was indeed changed in 2005, then** the pressure ratings of the pipe components specified in the relevant standards published after 2005 should be updated accordingly. I checked the GB/t9119-2010 standard, and the pressure grades used are still PN1.0, PN1.6, PN2.5, PN4.0, PN6.3, with PN10 as the notation method. Well, it’s quite embarrassing now; everything is in chaos. On the same material requisition form, PN10 refers to 1 MPa for some items (as specified in the GB/t9119-2010 standard), while others use the provisions of the GB/T1048-2005 standard, where PN10 denotes 10 MPa. Speechless! ! !
This post was last edited by “Hasty Passerby” on October 30, 2017, at 14:04. Pg hasn’t been used for several years now. The units employed vary depending on the standard; for instance, in the DIN standard, the unit for PN is bar, while in China’s national standards, the European series uses MPa (bar) as the unit； The American series in US or national standards is expressed in pounds. Pressure grade diagrams in HG/T standards
The unit is generally not indicated after the nominal pressure, but when Bar or Mpa is used (1 Mpa = 10 Bar), the unit must be specified; otherwise, it is easy to confuse the pressure levels and make mistakes. The unit of Pg is kgf/cm2, which is equivalent to Bar. The unit for PN in DIN standards is bar, while the European series in national standards uses MPa as the unit ； The American series in US or national standards is expressed in pounds. For example, for the nominal pressure PN10, some standards specify 10 Mpa, while others specify 10 Bar (which is equivalent to 1 Mpa). This is explained on page 686 of \"Pressure Pipeline Technology\", \"Pressure Pipeline Approval Tutorial\", and \"Process Pipeline Design and Engineering Applications\"
Different standards result in different notations; the notation methods for the chemical industry standard HG and the petrochemical industry standard SH are different.