ASME standard B16.47 applies to "standard" flanges greater than 24" diameter. This standard does not define or consider slip-on flanges; it treats only weld neck type flanges.

Slip-on flanges larger than 24" diameter may be considered by some other standards, such as API and AWWA. However, these flange standards are not accepted by ASME Boiler and Pressure Vessel Code as standard pressure components. Such flanges can be used for fabrication but must be analyzed by Appendix 2 and must be manufactured of appropriate material.