auzie5
Mechanical
- May 8, 2009
- 94
CSA Z245.12 (Steel Flanges) Table 1 (p. 14 in 2009 edition) provides maximum cold working-pressure ratings for various nominal pressure classes (PN 20 to PN 420). These cold working pressure ratings are for temperatures lower than or equal to 120 deg C.
Table B.1 (p. 39 in 2009 edition) provides a cross-reference between CSA Nominal Pressure Class (i.e. PN 50) and equivalent ASME Class Designations (CL 300) to indicate the manufacturing dimensions and maximum allowable working pressure, considering the material used and the operating temperature. This is a very helpful table since it allows the designer to de-rate the working pressure of CSA Z245.12 flanges as temperature increases using the Pressure – Temperature Rating tables in ASME B16.5.
However, I am unclear on which Material Group in ASME B16.5 to use for CSA Z245.12 flange grades.
Example:
CSA Z245.12, Gr. 448, PN 50, RFWN Flange
From Table B.1, equivalent ASME Class Designation is CL300. However, which materials group in B16.5 covers a material equivalent to Gr. 448? Group 1.1 Materials (covered under Table 2-1.1 in B16.5) are for A105, A350-LF2, etc. however, those materials have a significantly lower yield strength than Gr. 448 (i.e. 241 MPa vs. 448 MPa).
All other things being equal, shouldn’t a flange made from Gr. 448 material have higher allowable working pressures than a flange made from A105?
Thanks in advance for any thoughts.
KDW
Table B.1 (p. 39 in 2009 edition) provides a cross-reference between CSA Nominal Pressure Class (i.e. PN 50) and equivalent ASME Class Designations (CL 300) to indicate the manufacturing dimensions and maximum allowable working pressure, considering the material used and the operating temperature. This is a very helpful table since it allows the designer to de-rate the working pressure of CSA Z245.12 flanges as temperature increases using the Pressure – Temperature Rating tables in ASME B16.5.
However, I am unclear on which Material Group in ASME B16.5 to use for CSA Z245.12 flange grades.
Example:
CSA Z245.12, Gr. 448, PN 50, RFWN Flange
From Table B.1, equivalent ASME Class Designation is CL300. However, which materials group in B16.5 covers a material equivalent to Gr. 448? Group 1.1 Materials (covered under Table 2-1.1 in B16.5) are for A105, A350-LF2, etc. however, those materials have a significantly lower yield strength than Gr. 448 (i.e. 241 MPa vs. 448 MPa).
All other things being equal, shouldn’t a flange made from Gr. 448 material have higher allowable working pressures than a flange made from A105?
Thanks in advance for any thoughts.
KDW