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This standard is developed in accordance with the rules given in GB/T 1.1-2020 Directives for standardization — Part 1: Rules for the structure and drafting of standardizing documents.
This document replaces GB/T 12242-2005 Performance test code — Pressure relief devices. In addition to a number of editorial changes, the following technical changes have been made with respect to GB/T 12242-2005:
a) Terms and definitions of field testing and opening pressure have been added, and the term and definition of reclosing pressure-relieving device have been changed (see Clause 3 herein; Clause 3 of 2005 Edition);
b) The diameter requirements for the test vessel for the operational characteristics and flow capacity testing have been deleted (4.2 in 2005 Edition);
c) The requirements for the installation of orifice plates and measurement of flow have been added [see 5.2.4.3f)];
h) The requirements of “procedure” in test procedure have been modified (see 5.4 herein; 5.4 of 2005 Edition);
e) The resistance test requirements of different non-reclosing pressure relief devices have been added (see 5.4.8.5);
f) The test requirements for measuring the set pressure of non-reclosing pressure relief device with incompressible fluid have been added (see 5.4.9).
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. The issuing body of this standard shall not be held responsible for identifying any or all such patent rights.
This standard was proposed by the China Machinery Industry Federation.
This standard is under the jurisdiction of the National Technical Committee on Pressure Relief Devices of Standardization Administration of China (SAC/TC 503).
This standard was first issued in 1989 (GB/T 12242-1989). Its first revision was issued in 2005, and this is the second revision.
Pressure relief devices — Performance test code
1 Scope
This code specifies the test methods of the operation performance test (including mechanical characteristics), flow capacity and resistance coefficient of pressure relief devices.
This code is applicable to the situation where the test procedure has various inlet and outlet conditions and the test medium is steam, gas (air) or liquid (water) with known physical properties; the pressure relief devices include reclosing pressure-relieving devices and non-reclosing pressure relief devices, as follows:
a) safety valve;
b) rupture disk device;
c) breaking/shear pin device;
d) fusible plug device.
Other pressure relief devices may be tested provided all parties to the test agree to accept the provisions of this code.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 2624.1 Measurement of fluid flow by means of pressure differential devices inserted in circular cross-section conduits running full — Part 1: General principles and requirements
GB/T 2624.2 Measurement of fluid flow by means of pressure differential devices inserted in circular cross-section conduits running full — Part 2: Orifice plates
GB/T 12241 Safety valves — General requirements
GB/T 12243 Spring loaded safety valves
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3 Terms and definitions
For the purposes of this document, the terms and definitions given in GB/T 12241 and the following apply.
3.1 General terms
3.1.1
pressure relief device
device designed to prevent internal medium pressure from rising above a predetermined maximum pressure in a pressure vessel exposed to emergency or abnormal conditions
3.1.2
pressure relief valve; PRV
valve designed to prevent internal medium pressure from rising above a predetermined maximum pressure in a pressure vessel exposed to emergency or abnormal conditions
3.1.3
field testing
testing of a pressure relief device installed on a system to determine some or all of its operating characteristics
3.1.4
in-service testing
testing of a pressure relief device installed on and protecting a system, using system pressure or an external pressure source, with or without an auxiliary lift device to determine some or all of its operating characteristics
3.1.5
flow capacity testing
testing of a pressure relief device to determine its operating characteristics, including measured relieving capacity
3.1.6
bench testing
testing of a pressurization system to determine the set pressure and closure member tightness of pressure relief device
3.2 Types of pressure relief devices
3.2.1
reclosing pressure-relieving device
pressure relief device designed to actuate on inlet static pressure and reclose after normal conditions have been restored
Note: There are direct spring-loaded, pilot-operated and power-actuated types in the structural type.
3.2.2
non-reclosing pressure relief device
pressure relief device designed to actuate and remain open after operation. A manual resetting means may be provided.
Note: Non-reclosing pressure relief devices include rupture disk device, breaking pin device, buckling pin device, shear pin device and fusible plug device.
3.2.2.1
rupture disk device
non-reclosing pressure relief device actuated by the static differential pressure between the inlet and outlet of the device and designed to function by the bursting of a pressure containing disk
3.3 Dimensional characteristics of pressure relief devices
3.3.1
discharge area
minimum sectional area of fluid flow path during valve discharge
3.3.2
nozzle area
minimum cross-sectional area of flow between valve inlet end and closure member sealing surface
3.3.3
nozzle diameter
diameter corresponding to the nozzle area
3.3.4
curtain area
area of the cylindrical or conical discharge opening between the seating surfaces created by the lift of the disk above the seat
Note: See Figure 1 for curtain area.
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Keys:
L——lift;
D——smallest diameter at which seat touches disk;
DB——other diameter of frustum of cone;
B——slant height of frustum of cone;
θ——seat angle;
R——radius.
Note: Curtain area is the discharge area unless the disk attains sufficient lift for the nozzle area to become the smallest sectional area of the passage.
Figure 1 Typical curtain areas of safety valves
3.3.5
lift
actual travel of the disk away from closed position
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3.3.6
rated lift
design lift at which a valve attains its rated relieving capacity
3.3.7
seat angle
angle between the axis of a valve and the seating surface
Note: A flat-seated valve has a seat angle of 90°.
3.4 Dimensional characteristics of non-reclosing pressure relief devices
3.4.1
net flow area
area that determines the flow after a non-reclosing pressure relief device has operated
Note: The (minimum) net flow area of a rupture disk is the calculated net area after a complete burst of the disk, with appropriate allowance for any structural members that may reduce the net flow area through the rupture disk device.
3.5 Operational and flow capacity characteristics of pressure relief devices
3.5.1
set pressure
value of increasing inlet static pressure at which a pressure relief device displays one of the operational characteristics as defined under opening pressure, popping pressure, start-to-leak pressure, burst pressure, or breaking pressure (The applicable operating characteristic for a specific device design is specified by the device manufacturer.)
3.5.2
over pressure
pressure increase over the set pressure of a pressure relief valve, under which the lift of safety valve reaches the value specified by the manufacturer
Note: over pressure is usually expressed as a percentage of set pressure.
3.5.3
re-seating pressure
value of decreasing inlet static pressure at which the valve disk reestablishes contact with the seat or at which lift becomes zero
3.5.4
blowdown
difference between set pressure and re-seating pressure
Note: Blowdown is expressed as a percentage of set pressure or in pressure units.
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3.5.5
relieving pressure
set pressure plus over pressure
3.5.6
flow-rating pressure
inlet stagnation pressure at which the relieving capacity of a pressure relief device is measured
3.5.7
back pressure
static pressure existing at the outlet of a pressure relief device due to pressure in the discharge system
3.5.8
built-up back pressure
pressure existing at the outlet of a pressure relief device caused by the flow through that particular device into a discharge system
3.5.9
superimposed back pressure
the static pressure existing at the outlet of a pressure relief device at the time the device is required to operate
Note: It is the result of pressure in the discharge system from other sources.
3.5.10
burst pressure
value of inlet static pressure at which a rupture disk device functions
3.5.11
specified burst pressure of a rupture disk device
value of increasing inlet static pressure, at a specified temperature, at which a rupture disk is designed to function
3.5.12
breaking pressure
value of inlet static pressure at which a breaking pin, buckling pin device or shear pin device functions
3.5.13
secondary pressure
pressure existing in the passage between the actual discharge area and the valve outlet in a pressure relief valve
3.5.14
simmer pressure
audible or visible escape of fluid between the seat and disk at an inlet static pressure below the set pressure of pressure relief valve and at no measurable capacity
Note: It applies to safety relief valves on compressible-fluid service.
3.5.15
theoretical relieving (discharge) capacity
calculated capacity of a theoretically perfect nozzle having a minimum cross-sectional flow area equal to the nozzle area of a pressure relief valve or net flow area of a non-reclosing pressure relief device
Note: It is expressed in gravimetric or volumetric units.
3.5.16
measured relieving (discharge) capacity
relieving capacity of a pressure relief device measured at the flow-rating pressure
Note: It is expressed in gravimetric or volumetric units.
3.5.17
rated relieving capacity; certified discharge capacity
portion of the measured relieving capacity permitted by the applicable code or regulation to be used as a basis for the application of a pressure relief device
3.5.18
equivalent calculated capacity
calculated capacity of a pressure relief device when the service conditions for pressure, temperature or medium are different from the applicable conditions of rated relieving capacity
3.5.19
rated coefficient of discharge
ratio of rated relieving capacity (certified discharge capacity) to theoretical relieving (discharge) capacity
3.5.20
chatter
abnormal rapid reciprocating motion of the movable parts of a pressure relief valve in which the disk contacts the seat
3.5.21
flutter
abnormal, rapid reciprocating motion of the movable parts of a pressure relief valve in which the disk does not contact the seat
3.5.22
reference conditions
those conditions of a test medium which are specified by either an applicable standard or an agreement between the parties to the test, which may be used for uniform reporting of flow capacity testing results
4 General provisions
4.1 The measurement deviation of this standard test is as follows: for the flow capacity testing, the deviation of the final flow capacity measurement shall not exceed ±2.0% of the measured value; for the operational characteristics testing, the deviation of the pressure measurement shall not exceed ±0.5% of the measured value; for the in-service testing and bench testing, the deviation of the pressure measurement shall not exceed ±1.0% of the measured value.
4.2 To carry out the test specified in this code, the testing facility shall have the pressure and sufficient capacity required by the pressure relief device under test and meet the test requirements of the relieving pressure of the pressure relief device or pressure relief valve. The duration of the test shall be that required to obtain the necessary performance and capacity data under stable conditions. Operating conditions shall be maintained in accordance with the requirements of the procedure used.
4.3 Field installation or abnormal operating conditions may adversely affect the function of the pressure relief device. It is not the intent of this code to attempt to assess the suitability or reliability of the pressure relief device under such conditions.
4.4 It should also be noted that if the temperature of the medium used to test the pressure relief device differs substantially from the temperature to which the pressure relief device is subjected while in service, the functional characteristics will be different from the test pressures, i.e., opening, blowdown, and burst pressure. In this case, it is necessary to develop appropriate corrections for the pressure relief device under test to account for these differences which is outside the scope of this code
4.5 This code provides recommended test procedures and instrumentation for testing devices. Other test procedures or instrumentation may be used provided they can be demonstrated as having accuracy and reliability at least equal to the requirements of this code. If another procedure or instrumentation is used, this must be agreed in writing by the parties to the test prior to the test.
4.6 The test results shall be reported as measured and calculated. Only tests which comply fully with the mandatory requirements of this code may be designated as tests conducted in accordance with this code.
4.7 Special consideration should be given to adequate design and over pressure protection to the piping system and components, safe discharge from the pressure relief devices undergoing test, and the high noise level usually associated with the discharge of pressure relief devices. The interested parties to the test should assure the testing facility meets the minimum mandatory requirements.
Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 General provisions
5 Operational characteristics and flow capacity testing of pressure relief devices
5.1 Test apparatus and instruments
5.2 Methods of measurements
5.3 Requirements for test installation
5.4 Test procedure
5.5 Computation of results
5.6 Test summary report
6 In-service and bench testing
6.1 Instruments and methods of measurements
6.2 In-service testing procedures
6.3 Bench testing procedures
6.4 Seat tightness test
6.5 Computation of results
6.6 Test summary report
Annex A (Informative) Test report form
Annex B (Informative) Test summary report form
Annex C (Informative) Examples of flow error determination
