... .5 5.Certificate:API,ISO,CE,eg astm a105n carbon steel weld neck flange size 1/2" to 24" ... , ASME B16.36,DIN2505,EtcMaterialCarbon steel(ASTM A105,Q235,A350LF2,A350LF3,Etc)Stainless steel(ASTM A182 F304, F304L,F316, ... F321,F347,F310F44F51,A276 S31803, A182, F43,Etc)Alloy steel(ASTM A694 F42,F46,F52,F56,F60,F65,F70, ... On Flange Blind FlangeWelding Neck Flange ISO certificate carbon steel flange(supplier)