This International Standard specifies the types, pressure-temperature ratings, minimum dimensions and materials of stainless steel fittings for threaded connections in accordance with ISO 7-1, used for ordinary piping for steam, air, gas, water, oil, etc.
GSO ISO 4144:2013 history
2013GSO ISO 4144:2013 Pipework -- Stainless steel fittings threaded in accordance with ISO 7-1