1.0.1 This specification is only applicable to the setting and calculation of safety valves for preventing overpressure of pressure vessels with pressure greater than 0.2MPa in chemical industry production installment, excluding the ultrahigh pressure systems with pressure greater than 100MPa.
It is applicable to safety valves of pressure vessels and pipelines within the above range in chemical industry production installment; it is not applicable to safety valves used in pressure vessels in other industries, such as tank trucks, various gas cylinders, boiler systems, non-metallic material vessels, nuclear industry, electric power industry, etc.
1.0.2 The calculation method is quoted from the Supervision regulation on safety technology for pressure vessel and API-520, 2.3. When applying this specification, the same criterion shall be adopted to calculate the discharge capacity and discharge area.
2 Terms
2.0.1
safety valve
safety valve acted by a spring or controlled by a pilot valve. When the static pressure at the inlet exceeds the set pressure, the valve flap rises to relieve the overpressure in the protected system, and when the pressure drops to the reseating pressure, the safety-relief valve can automatically close
2.0.2
pilot valve
auxiliary pressure-relieving valve to control the action of main valve
2.0.3
full lift safety valve
when the static pressure at the inlet of the safety valve reaches its set pressure, the valve flap quickly rises to the maximum height to discharge the overpressure material to the maximum extent. Generally it is used for compressible fluids. The maximum lifting height of the valve flap shall not be less than 1/4 of the throat diameter
2.0.4
low lift safety valve
when the static pressure at the inlet of the safety valve reaches its set pressure, the valve flap rises proportionally with the increase of inlet pressure to minimize the discharge amount of materials which shall be discharged. Generally it is used for incompressible fluids. The maximum lifting height of the valve flap shall not be less than 1/20~1/40 of the throat diameter
1 Application scope 2 Terms 3 Normative references 4 Relation table of pressure 5 Installation of safety valves 6 Selection of safety valves 7 Calculation of discharge capacity under various accident conditions 8 Calculation of minimum discharge area 9 Safety valve for gas storage vessel 10 Determination of safety valve model 11 Data sheet, computation sheet and summary list of safety valve 12 Design of safety valve inlet pipeline 13 Design of safety valve outlet pipeline 14 Calculation and data sheet of reaction force at safety valve outlet 15 Installation precautions 16 Attached figures and tables 17 Symbols
1 Application scope
1.0.1 This specification is only applicable to the setting and calculation of safety valves for preventing overpressure of pressure vessels with pressure greater than 0.2MPa in chemical industry production installment, excluding the ultrahigh pressure systems with pressure greater than 100MPa.
It is applicable to safety valves of pressure vessels and pipelines within the above range in chemical industry production installment; it is not applicable to safety valves used in pressure vessels in other industries, such as tank trucks, various gas cylinders, boiler systems, non-metallic material vessels, nuclear industry, electric power industry, etc.
1.0.2 The calculation method is quoted from the Supervision regulation on safety technology for pressure vessel and API-520, 2.3. When applying this specification, the same criterion shall be adopted to calculate the discharge capacity and discharge area.
2 Terms
2.0.1
safety valve
safety valve acted by a spring or controlled by a pilot valve. When the static pressure at the inlet exceeds the set pressure, the valve flap rises to relieve the overpressure in the protected system, and when the pressure drops to the reseating pressure, the safety-relief valve can automatically close
2.0.2
pilot valve
auxiliary pressure-relieving valve to control the action of main valve
2.0.3
full lift safety valve
when the static pressure at the inlet of the safety valve reaches its set pressure, the valve flap quickly rises to the maximum height to discharge the overpressure material to the maximum extent. Generally it is used for compressible fluids. The maximum lifting height of the valve flap shall not be less than 1/4 of the throat diameter
2.0.4
low lift safety valve
when the static pressure at the inlet of the safety valve reaches its set pressure, the valve flap rises proportionally with the increase of inlet pressure to minimize the discharge amount of materials which shall be discharged. Generally it is used for incompressible fluids. The maximum lifting height of the valve flap shall not be less than 1/20~1/40 of the throat diameter
Contents of HG/T 20570.2-1995
1 Application scope
2 Terms
3 Normative references
4 Relation table of pressure
5 Installation of safety valves
6 Selection of safety valves
7 Calculation of discharge capacity under various accident conditions
8 Calculation of minimum discharge area
9 Safety valve for gas storage vessel
10 Determination of safety valve model
11 Data sheet, computation sheet and summary list of safety valve
12 Design of safety valve inlet pipeline
13 Design of safety valve outlet pipeline
14 Calculation and data sheet of reaction force at safety valve outlet
15 Installation precautions
16 Attached figures and tables
17 Symbols
