ISO 7121:2016 specifies the requirements for a series of steel ball valves suitable for general-purpose industrial applications.It covers valves of the nominal sizes- DN 8, 10, 15, 20, 25, 32, 40, 50, 65, 80, 100, 150, 200, 250, 300, 350, 400, 450, 500, and 600 (NPS 1/4, 3/8, 1/2, 3/4, 1, 11/4, 11/2, 2, 21/2, 3, 4, 6, 8, 10, 12, 14, 16, 18, 20 and 24),and is applicable to the following pressure designations:- PN 10; 16; 25; 40; 63; 100;- Class 150; 300; 600; 800; 900.NOTE Valve characteristics are not necessarily available in all nominal sizes for all pressure designations. For example, Class 800 applies only for valves with threaded end and socket weld ends up to DN 65 (NPS 21/2) and Class 900 applies only for reduced bore body seat openings.It includes provisions for valve characteristics as follows:- flanged and butt-welded ends in sizes 15 ≤ DN ≤ 600 (1/2 ≤ NPS ≤ 24);- socket welding ends in sizes 8 ≤ DN ≤ 100 (1/4 ≤ NPS ≤ 4);- threaded ends in sizes 8 ≤ DN ≤ 50 (1/4 ≤ NPS ≤ 2);- body seat openings designated as full bore, reduced bore and double reduced bore;- materials;- testing and inspection.