This part of ISO 6149 specifies dimensions, performance requirements and test procedures for metric adjustable and non-adjustable heavy-duty (S series) stud ends and O-rings. Stud ends in accordance with this part of ISO 6149 may be used at working pressures up to 63 MPa [630 bar1)] for non-adjustable stud ends and 40 MPa (400 bar) for adjustable stud ends. The permissible working pressure depends upon the stud end size, materials, design, working conditions, application, etc. Conformance to the dimensional information in this part of ISO 6149 does not guarantee rated performance. Each manufacturer should perform testing according to the specification contained in this part of ISO 6149 to assure that components comply with the performance ratings. NOTE 1 A significant number of tests have been conducted to confirm the performance requirements of connection ends made from carbon steel. NOTE 2 This part of ISO 6149 applies to connectors detailed in ISO 8434-1, ISO 8434-3 and ISO 8434-4, and plugs in accordance with ISO 6149-4. See ISO 12151-4 for related hose fitting specification. NOTE 3 The Introduction of this part of ISO 6149 gives recommendations for ports and stud ends to be used for new designs in hydraulic fluid power applications.