ISO 9974-3 is accomplished by means of cutting surface. Spot-faced surface must be square to thread in port. Machining operations such as A and D6 not required when port surface complies with requirements.
ISO 9974-3 Connections for general use and fluid power -- Ports and stud ends with ISO 261 threads with elastomeric or metal-to-metal sealing -- Part 3: Stud ends with metal-to-metal sealing (type B)
This part of ISO 9974 specifies dimensions, performance requirements and test procedures for heavy-duty (S series), light-duty (L series) and extra-light-duty (LL series) stud ends with ISO 261 threads and metal- to-metal sealing. It also specifies the designation of these stud ends. These stud ends should not be used for leak-free hydraulic fluid power applications because they may leak if re-used.
Stud ends in accordance with this part of ISO 9974 maybe used at working pressures up to 10 MPa (100 bar1) for the LL series, 25 MPa (250 bar) for the L series and 40 MPa (400 bar) for the S series. The permissible working pressure depends upon the stud end size, materials, design, working conditions, application, etc.
For threaded ports and stud ends specified in new designs in hydraulic fluid power applications, only ISO 6149 is to be used. Threaded ports and stud ends in accordance with ISO 1179, ISO 9974 and ISO 11926 are not to be used for new designs in hydraulic fluid power applications.
Conformance to the dimensional information in this part of ISO 9974 does not guarantee rated performance. Each manufacturer should perform testing according to the specification contained in this part of ISO 9974 to assure that components comply with the performance ratings.