This specification covers spring-loaded, angle style, pressure relief valves for steam, gas, and liquid system applications. Pressure relief valves shall be of the following types and material grades: Type I, Grades A and B; Type II, Grades C and D; and Type III, Grades E and F. Hydrostatic shell test and set pressure, blowdown, and seat tightness test shall be performed to meet the specified requirements.

1.1 This specification covers spring-loaded, angle style, pressure relief valves for steam, gas, and liquid system applications (excluding boiler safety and hydraulic system relief valves).

1.2 The values stated in inch-pound units are to be regarded as standard. No other units of measurement are included in this standard.

1.3 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.