GB/T 12242-2021Pressure relief devices - Performance test code (English PDF)

3.1 General terms

3.1.1 Pressure relief device A device used to prevent the pressure of the internal medium from rising to exceed the predetermined maximum pressure when the pressure vessel is in an emergency or abnormal situation.

3.1.2 Pressure relief valve pressure relief valve; PRV A valve used to prevent the pressure of the internal medium from rising to exceed the predetermined maximum pressure when the pressure vessel is in an emergency or abnormal situation.

3.1.3 Field test fleldtesting In order to determine some or all of the working characteristics of the pressure relief device, the test of the pressure relief device installed on the system.

3.1.4 In-service testing In order to determine some or all of the working characteristics of the pressure relief device, use system pressure or use an external pressure source (with or without auxiliary Lifting device) A test of a pressure relief device installed on the system that is protecting the system.

3.1.5 Displacement test flowcapacitytesting Determining the operating characteristics of the pressure relief device includes a test to measure the displacement.

3.1.6 Benchtesting A test on a pressurized system to determine the set pressure of the pressure relief device and the tightness of the closure.

3.2 Types of pressure relief devices

3.2.1 Reclosing pressure-Relieving devices Designed as a pressure release device that is driven by the inlet static pressure and re-closes after returning to normal working conditions.

Note. The structure types are spring direct load type, pilot type, power operation type.

3.2.2 Non-reclosing pressure relief device A pressure release device that remains open after an action can provide a means of manual reset.

Note. Non-reclosing pressure release devices include rupture discs, breaking pins, bending pins, shear pins, and fusible plugs.

3.2.2.1 Rupture disk device The function of a non-reclosing pressure release device driven by the static pressure difference between the inlet and outlet of the device is realized by the blasting of the pressure-bearing piece.

3.3 Characteristic dimensions of pressure relief device

3.3.1 Dischargearea The minimum cross-sectional area of the fluid passage when the valve is discharged.

3.3.2 Nozzlearea The minimum cross-sectional area of the flow path from the inlet end of the valve to the sealing surface of the closing member.

3.3.3 Nozzlediameter Corresponds to the diameter of the flow channel area.

3.3.4 Curtainarea When the valve flap rises above the valve seat, the cylindrical or conical discharge channel area is formed between the sealing surfaces.

Note. The area of the curtain is shown in Figure 1.

3.3.7 Seatangle The angle between the valve axis and the sealing surface.

Note. The bevel angle of the sealing surface of the flat sealing valve is 90°.

3.4 Characteristic dimensions of non-reclosing pressure relief devices

3.4.1 Net flow area netflowarea The area of the flow rate is determined after the non-reclosing pressure release device operates.

Note. The (minimum) net flow area of a rupture disc is the calculated net area after it is completely ruptured, and it has an appropriate tolerance, because some structural parts of the rupture disc May reduce its net circulation area.

3.5 Action and displacement characteristics of the pressure release device

3.5.1 Set pressure The inlet static pressure raised by the pressure release device, under which the device exhibits the definition of opening pressure, sudden jump pressure, and starting leakage pressure One of the action characteristics of force, burst pressure, and breaking pressure (for a specific device design, the applicable action characteristics are determined by the device manufacturer. set).

3.5.2 Overpressure The pressure increase exceeding the set pressure of the pressure release valve, at which the safety valve reaches the opening height specified by the manufacturer.

Note. The excess pressure is usually expressed as a percentage of the set pressure.

3.5.3 Re-seating pressure After the pressure release valve is discharged, the disc contacts the valve seat again, that is, the pressure when the opening height becomes zero.

3.5.4 Blowdown The difference between the set pressure and the return pressure.

Note. The opening and closing pressure difference is expressed as a percentage of the set pressure or in pressure units.

3.5.5 Discharge pressure Set pressure plus over pressure.

3.5.6 Rated discharge pressure flow-ratingpressure The inlet static pressure when measuring the displacement of the pressure release device.

3.5.7 Backpressure The static pressure generated at the outlet of the pressure relief device due to the presence of pressure in the exhaust system.

3.5.8 Built-upbackpressure The pressure generated at the outlet of the device as the medium flows through the pressure relief device into the discharge system.

3.5.9 Superimposedbackpressure The pressure that exists at the outlet of the pressure relief device immediately before it operates.

Note. The additional back pressure is caused by other pressure sources in the exhaust system.

3.5.10 Burst pressure When the bursting disc device operates, its inlet static pressure.

3.5.11 Specified burst pressure of bursting disc device specified burst pressure of a rupture disk device The inlet static pressure of the bursting disc device is increased, and the bursting disc is designed to burst at this pressure at a specified temperature.

5.1 Test equipment and instruments

5.1.1 Test device The layout of the test device is shown in Figure 2~Figure 7 and Figure 9. To ensure its accuracy within the expected use range.

5.1.2.6 Steam calorimeter The steam calorimeter should be calibrated at the time of its installation and within the specified period. When the measurement result shows that the reading is obviously wrong At time or after reinstallation, calibration should be performed again.

5.1.2.7 Flowmeter combination The calibration of the flowmeter should include the actual pipes and all accessories on the upstream and downstream sides of the flowmeter. The connection between the container and the valve. The calibration should be completed before the execution of the formal test by the method of comparison, that is, the flow measurement value should be calibrated in advance. The value measured by the accurate flowmeter device is compared, and the latter's calibration is done with the aid of the original device or mechanism. About pre-calibration The agreement of the flow meter device should make the deviation of the final overall test result within ±2.0%. The calibration should be at the smallest, Performed at middle and maximum flow. For valves with different inlet connection forms, the connections should be made by laboratory personnel during manufacture or purchase. Calibration by the operator. In addition, the flow meter device should be recalibrated at least once every 5 years as described above. This recalibration should include the use of at least two Various sizes of connectors. Calibration records should be kept and audited by relevant parties. If a change is made to the equipment, it should be assessed that the change may affect the system. For the impact of system calibration, a new calibration should be performed when deemed necessary.

5.1.3 Adjustments in the test When collecting data, no adjustments should be made to the pressure release device. After any change or deviation of the test conditions, adequate Time allows the flow, temperature and pressure to stabilize before collecting data.

5.1.4 Test records and test results The test record should include all observations, measurements, meter readings and meter calibration records (when needed) of the test object. Original test record The records should be kept by the institution conducting the test. Copies of all test records should be submitted to all parties to the test. The correction and correction value should be loaded into the test record separately record. The test summary report shall be made in accordance with the provisions of 5.6.

5.1.5 Measurement error Preliminary tests should be carried out to determine that the specified instruments and procedures can meet the error limits specified in

4.1 for the final displacement measurement. limit. An error analysis after the test should also be performed, unless all parties to the test agree and verify that the specified instruments and procedures including the discreteness of the data are based on The test specifications are used and executed to confirm that the error determined by the preliminary test is still valid after the test. The error determination should be determined by the shape of the test chamber Documented for review.

5.2 Measurement method

5.2.1 Atmospheric pressure measurement Atmospheric pressure should be measured with a barometer. When calculating including displacement, if the rated discharge pressure of the pressure relief device is equal to or higher than At 0.15MPa (gauge pressure), the average atmospheric pressure of the test area can meet the accuracy requirements of this document. On this occasion, the recorded The pressure can be average atmospheric pressure.

5.2.2 Temperature measurement The requirements for temperature measurement are as follows:

a) According to the operating conditions, temperature measurement can use glass tube liquid thermometer, bimetal thermometer, resistance thermometer or thermoelectric I. The glass tube liquid thermometer should be inserted into the sleeve, and the bimetal thermometer, resistance thermometer or thermocouple can be directly inserted into the tube In the channel, it can also be inserted into the casing. When the temperature is lower than 150°C, the temperature measuring device should be directly inserted into the pipeline without additional casing.

b) When taking any temperature measurement, the following measures should be taken. 1) Except for the measured medium, there should be no large heat transfer between the temperature measuring device and the outside world due to radiation or conduction. 2) The immediate vicinity of the insertion point and the exposed part of the temperature measuring device should be insulated. 3) The insertion depth of the small diameter pipe temperature measuring device should pass through the center line of the pipe; when the pipe diameter exceeds 300mm, the temperature measuring device The device should be inserted into the media stream at least 150mm deep. 4) On pipelines that transport compressible fluids, the temperature measuring device should be installed when the maximum medium flow rate does not exceed when performing flow measurement. 30m/s. If this is not possible, the temperature reading may need to be corrected to the appropriate static or full temperature. 5) The insertion position of the temperature measuring device should be such that the measured temperature represents the temperature of the flowing medium.

c) When using a glass tube mercury thermometer to measure temperature, the thermometer should have a graduated rod. When the measured temperature is the same as the ambient temperature When the difference is greater than 5°C and the mercury is partially exposed, the exposed rod should be corrected, or an exposed rod thermometer should be used.

d) When using a thermometer casing, the casing should be thin-walled and its diameter should be as small as possible. There should be no corrosion or debris on the outside of the casing. casing The inside should be filled with appropriate fluid, but mercury should not be used. If mercury is used, appropriate precautions should be taken.

e) If a thermocouple is used, it should have a soldered hot end, and it should be calibrated in the expected range of use together with its external wires. The thermocouple should be made of materials suitable for the measured temperature and medium. The electromotive force should be measured with a potentiometer or millivoltmeter. The cold junction of the thermocouple should be formed by using an ice bath (reference standard) or by installing a compensation circuit on the potentiometer.

5.2.3 Pressure measurement The requirements for pressure measurement are as follows:

a) The pressure measuring point should be arranged in the area where the flow is basically parallel to the pipe wall or container wall. When measuring a static pressure difference of less than 0.1MPa, A liquid pressure gauge can be used.

b) The pressure of the test vessel should be the static pressure measured through the pressure tap shown in Figure 2.

c) The back pressure should be the static pressure measured through the pressure tap shown in Figure 3, Figure 5 and Figure 6.

d) If there is a water level difference or other level difference between the pressure measurement point and the pressure gauge, the pressure reading should be appropriately corrected.

5.2.4 Flow measurement

5.2.4.1 The methods for measuring the displacement of the pressure release device are.

a) Subsonic inferred flowmeter, including orifice plate, flow nozzle and venturi tube;

b) Sound velocity inferred flowmeter, including plug flow nozzle;

c) Volume method or gravimetric method for directly collecting the discharge medium or its condensate.

5.2.4.2 The following methods shall be used to measure the displacement of the pressure release device as appropriate.

a) The steam flow rate when the back pressure is atmospheric pressure, using the method 5.2.4.1a) or 5.2.4.1c);

b) The steam flow rate when the back pressure is higher than the atmospheric pressure, use the method 5.2.4.1a);

c) The flow of air or gas when the back pressure is atmospheric pressure, using the method 5.2.4.1a) or 5.2.4.1b);

d) The flow of air or gas when the back pressure is higher than atmospheric pressure, using the method 5.2.4.1a);

e) The liquid flow rate when the back pressure is atmospheric pressure, using the method 5.2.4.1a) or 5.2.4.1c);

f) The liquid flow rate when the back pressure is higher than the atmospheric pressure, use the method 5.2.4.1a).

Note. During the test, the back pressure may be higher than the atmospheric pressure. Pay attention to the use of the sound velocity inferred flowmeter.

5.2.4.3 One-time measuring element.

a) The primary measuring element should be placed on the upstream side of the inlet of the pressure relief device under test. Installation requirements and meter location are shown in Figure 2.hole The ratio of the plate hole diameter to the pipe inner diameter should be between

5.2.7 Conditions under which correction can be carried out

5.2.7.1 Steam. The reference condition is dry saturated steam. In the test, the steam condition at the inlet of the pressure release device should be that the steam dryness is not small At 98% or overheating is not more than 10°C.

5.2.7.2 Water. The reference condition is 18°C~24°C. The temperature range of the water at the inlet of the pressure release device in the test should be 5°C~50°C.

5.2.7.3 Air and other gases. the reference condition is 13°C~24°C. Air or other gas at the inlet of the pressure release device during the test The temperature range should be -18°C~93°C.

5.2.7.4 If the test condition is not within the range of 5.2.7.1~5.2.7.3, the correction from the actual test condition to the reference condition cannot be carried out. The actual test pressure should not be corrected.

5.2.8 Medium composition A medium with well-defined physical properties should be used as the test medium. If there is any doubt about the physical properties of the fluid, physical experiments or chemical Learn to analyze to determine.

5.3 Test installation requirements

5.3.1 The pressure release device under test shall use connecting accessories (flange type, thread type or welding type, etc.). The acceptable internal cross-sectional shape is shown in Figure 8) Install directly on the test vessel. As long as it does not affect the accuracy of the test results, other connection accessories can also be used; no matter which one is used To connect in any way, it should be ensured that the inner diameter of the connection accessory test vessel interface is greater than the inner diameter of the pressure release device under test.

5.3.2 For the test where the back pressure before discharge is atmospheric pressure, the test arrangement should be such that the medium is directly discharged from the pressure release device to the atmosphere or the condenser (see Figure 2, Figure 3 and Figure 4). When using a discharge pipe, the pipe size should be at least equal to the outlet size of the pressure relief device. Support for discharge pipe Should be independent of the pressure relief device, its support method should not affect the action of the pressure relief device. Measures should be taken to ensure the pressure relief device And the discharge pipeline is strong enough to withstand the combined force generated by the discharge.