Defines dimensional characteristics of the nut end of 8 degree 30' straight metric-size unions and locking ring assembly with elastomer O-rings for use on aerospace equipment. Applicable to all straight metric-size unions with locking ring assembled to standard EN 2607 - and used in hydraulic systems with a maximum pressure of 28000 kPa for which the principle of a metric-size "DYNAMIC BEAM SEAL" coupling with a 8 degree 30' conical sealing surface has been selected.