Connections for general use and fluid power -- Ports and stud ends with ISO 228-1 threads with elastomeric or metal-to-metal sealing -- Part 1: Threaded ports
ISO 1179-1:2013 specifies dimensions for ports with ISO 228‑1 threads for use with non-adjustable stud ends described in ISO 1179‑2, ISO 1179‑3 and ISO 1179‑4 and with adjustable stud ends described in ISO 1179‑3.
Ports in accordance with ISO 1179-1:2013 are applicable for use with ISO 1179‑2 heavy-duty (S series) stud ends with type E sealing at working pressures up to 63 MPa (630 bar) and light-duty (L series) stud ends at working pressures up to 25 MPa (250 bar), ISO 1179‑3 light-duty (L series) stud ends with type G sealing at working pressures up to 31,5 MPa (315 bar), and with ISO 1179‑3 light-duty (L series) adjustable stud ends with type H sealing at working pressures up to 20 MPa (200 bar), and ISO 1179‑4 stud ends with type B sealing at working pressures up to 40 MPa (400 bar) for the S series, up to 25 MPa (250 bar) for the L series, and up to 10 MPa (100 bar) for the LL series, except for the G2 size port, which in hydraulic fluid power systems is used mainly with accumulators and for which ISO 1179‑3 and ISO 1179‑4 do not specify stud ends. The permissible working pressure depends upon size, materials, design, working conditions, application, etc.
source: ISO 1179-1:2013