BS 6759-2:1984

Foreword
Committees responsible
Specification
Section one. General
1. Scope
2. Definitions
Section two. Material requirements and limitations
3. Pressure containing components
Section three. Design and construction
4. General
5. Helical compression springs
Section four. Production testing and inspection
6. General
7. Pressure tests
8. Repair of defects in forgings and castings
Section five. Marking and preparation for despatch
9. Marking
10. Preparation for despatch
Section six. Performance testing
11. Type testing of safety valves for operating and
     flow characteristics using air or other gas of
     known characteristics
12. Tests to determine operating characteristics
13. Test to determine flow characteristics
14. Determination of coefficient of discharge and
     certified discharge capacity
15. Equivalent capacity
Appendices
A. Derivation of equation (11) for the certified
     capacity of a safety valve for air
B. Derivation of compressibility factor Z
Tables
1. Spring materials and characteristics
2. Value of the stress correction factor for
     curvature (K)
3. Load/length tolerances
4. Minimum duration of pressure test
5. Values of C relative to values of k
6. Capacity correction factors for back pressure (Kb)
Figures
1. Illustration of area definitions
2. Illustration of an end coil
3. Spring plate
4. Compressibility factor Z as a function of reduced
     pressure pr and reduced temperature Tr

Describes requirements for design, inspection, testing and flow certification relating to safety valves for air receivers and compressed air or inert gases. Not applicable to the following: protection of low pressure storage tanks storing liquefied gases at atmospheric pressure covered by BS 799 : Part 5, BS 2594, BS 2654 and BS 5387, and protection of vessels and containers used for transport of fluids under pressure.