This International Standard specifies quality control testing methods and test conditions for the characterization of microstructure in relation to relevant properties in ferritic/austenitic (duplex) stainless steel components supplied in the solution annealed condition and fabrication welds in the as welded condition. This International Standard supplements the relevant product and fabrication standards with respect to destructive testing methods including sampling of test specimens, test conditions and test acceptance criteria to show freedom from deleterious intermetallic phases and precipitates in duplex stainless steels. In addition this International Standard specifies how testing and test results shall be documented by the testing laboratory. NOTE 1 This International Standard is based upon experience with duplex stainless steels in offshore oil and gas industry applications including topside and subsea hydrocarbon service, sea water service as well as structural use. NOTE 2 The austenite spacing is relevant to the susceptibility of duplex stainless steels to hydrogen induced stress cracking (HISC) in subsea applications where cathodic protection is applied. This falls outside the scope of this International Standard. Reference is made to DNV/GL RP-F112 [6].