... ,202,304,304L,316,316L,321,etc. 2.High precision 3.Small-bore WE ARE THE PROFESSIONAL PIPE MANUFACTURER HAS 7 ... CAPS/FLANGESURFACE TREATMENT 1. BARED 2. BLACK PAINTING(BLACK VARNISH)3. TRANSPARENT OIL,4. HOT GALVANIZEDINSPECTION HYDRAULIC TESTING, EDDY CURRENT, INFRARED ...