Russian and international diameters of pipes – lookup table

Russian standard GOST, mm	Converting from mm into inch (1 inch=25.4 mm)	The closest size by ISO-3183-2, mm	Size by API corresponding to ISO, inch
530	20.87	508 and 559	20 and 22
720	28.35	711	28
820	32.28	813	32
1020	40.16	1016	40
1220	48.03	1219	48
1420	55.91	1422	56