Why does the SO type in flange standards not have an RJ sealing surface
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Why doesn’t the SO type in flange standards have an RJ sealing surface? The HG standards do not specify the seal face types and applicable ranges for various types of flanges. In the GB flange standards, the SO type does not have RJ seal face dimensions; however, the SO welded type can be used at PN110, PN150, and PN260 (for some small diameters). So, when using SO at such high pressures, can only RF/MFM/TG face types be employed? Is this not allowed by the standard, or is it an omission in the standard? ?
The SO welding type is used for small-diameter applications at high pressures, employing welding connections rather than flange connections.
According to the HG standards, the maximum operating pressure for SO flanges is 4.0 MPa, and the sealing surface of this grade does not use the RJ design.