1. SCOPE 1.1 This Standard Practice covers flanged or butt-weld end ball valves having in general, but not restricted to, round openings which may be full port, regular port, or reduced port types. The following characteristics shall be considered standard practice unless otherwise specified by agreement between manufacturer and purchaser. 1.2 Valves covered by this Standard Practice are suitable for use in general liquid and gas service. Their service pressures and temperatures generally conform to standards cited in Paragraph 2, but may be restricted by the materials used for their seats and seals, or by other special considerations. The 2010a Edition of MSS SP-72 updates the replaced 2010 Edition by: (1) re-including (from previous editions) Section 3.1.2 and the first sentence of Section 5.3.1; (2) additional descriptive notes were inserted in Sections 7.1.4 and 7.2.2; (3) the equation in Section 7.2.4.3 was clarified; (4) corrected the definition of MYS1 in Section 7.1.4 and AYS2 in Section 7.1.4; (5) corrected the definition of AYS5 and AYS6 in Section 7.2.2; and (6) additional editorial and conforming corrections.