In hydraulics, four-hole flanges with the connection pattern standardised in SAE j 518 (Figure S 1) are the most commonly used flange connections. The American SAE norm specifies two pressure stages 3,000/6,000 PSI (210/420 bar), nominal widths of 15 to 50 and fastening screws with UNC threads.
The SAE flange can be used as a two-part flange to connect pipelines to non-split counterfaces or as a one-part flange (SAE j 518c) to connect pipelines to one another.
The mounting dimensions of the SAE flanges were adopted in the international norm ISO 6162, published in 1994. ISO 6162 includes both flanges for metric fastening screws (series I) and those for fastening screws with UNC threads (series II).