Method and apparatus for measuring operating pressure in testing safety valves

Abstract

To provide a method for measuring a set pressure accurately and without variation, which can more reliably ensure the safety of equipment and containers. [Solution] The method includes the steps of supplying pressurized fluid to a safety valve, acquiring a pressure value of the supplied fluid, acquiring an actuation sound generated when the safety valve is actuated, and determining the pressure value at the time the actuation sound occurred as an actuation pressure value of the safety valve by linking the generation of the actuation sound and the pressure value via time. In one embodiment, the method includes the steps of determining a frequency component of the actuation sound, and detecting from the frequency component a specific frequency generated when fluid flows out from between the valve disc and valve seat of the safety valve. The time at which the specific frequency is detected is the time the actuation sound occurred, and the actuation pressure value is a blow-off pressure value. In another embodiment, the actuation pressure value is a blow-off pressure value, and the time at which the maximum value of the actuation sound occurred is the time the actuation sound occurred.

Description

[Technical Field]

[0001] The present invention relates to a technique for inspecting the operation of a safety valve, and more particularly to a method and apparatus for accurately measuring the onset pressure and discharge pressure to inspect whether a safety valve opens normally at a set pressure. [Background technology]

[0002] A safety valve is a device that automatically opens when the internal pressure exceeds a set pressure, releasing the steam, gas, liquid, etc. inside to the outside to reduce the pressure and prevent damage to equipment and piping, as well as explosions. Therefore, safety valves are extremely important in ensuring the safety of facilities, and regular inspections are required by law to maintain their functionality.

[0003] In safety valve inspections, the set pressure is evaluated. This evaluation is mainly carried out by measuring the onset pressure and the blow-out pressure. Here, onset of blow-out refers to a state in which the inlet pressure of the safety valve rises and a small amount of fluid begins to flow out from the outlet, and the inlet pressure at this time is the onset pressure. On the other hand, blow-out refers to a state in which the inlet pressure rises further and the safety valve pops, i.e., opens rapidly, continuously discharging the internal fluid, and the inlet pressure at this time is the blow-out pressure.

[0004] The method for measuring the set pressure of a safety valve varies depending on the type of fluid being used. In the case of a steam safety valve, the set pressure is inspected by measuring the blow-out pressure, taking into account the pop phenomenon caused by the sudden expansion of steam. This blow-out pressure is usually confirmed by listening. On the other hand, in the case of gas and liquid safety valves, emphasis is placed on the timing at which the gas or liquid begins to flow out, and the set pressure is inspected by measuring the blow-out pressure. This blow-out pressure is confirmed by listening to the sound made when blow-out begins, or by applying a film of soapy water to the outlet opening.

[0005] As a method for inspecting the operating pressure of a safety valve, the techniques disclosed in Patent Documents 1 to 4 have been proposed. Patent Document 1 relates to a method for inspecting whether a safety valve operates at a set pressure by detecting vibrations when gas starts to blow out from the safety valve and determining a pressure value. Patent Document 2 relates to a device for detecting blow-out pressure based on the force acting on components of the safety valve and the internal pressure. Patent Document 3 relates to a method for monitoring pressure fluctuations in a stationary state where the pressure is increased in stages and the supply is stopped, and if there is a fluctuation, determining the start of the fluctuation as the blow-out pressure. Patent Document 4 relates to a method for detecting bubbles generated from the valve by image processing while the opening of the safety valve is immersed in liquid, and determining whether the valve is open or closed based on the pressure change. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 6-137988 [Patent Document 2] Japanese Patent Application Laid-Open No. 2010-043967 [Patent Document 3] Japanese Patent Application Laid-Open No. 2018-162999 Summary of the Invention [Problem to be solved by the invention]

[0007] Because acoustic testing relies on the inspector's subjective judgment, it lacks reproducibility, objectivity, and reliability. Furthermore, measurements are prone to variance and error, making it difficult to obtain accurate pressure values. In particular, the set pressures of gas safety valves have become ultra-high in recent years. For example, the set pressure of safety valves for hydrogen stations is 90 MPa, and that of safety valves for hot isostatic pressing (HIP) equipment is 120 MPa. When conducting operational tests at ultra-high pressures, the testing equipment is covered with a polycarbonate safety fence to protect the inspector from accidents. Therefore, when inspecting these ultra-high-pressure valves, the safety fence blocks even the small initial sounds of blowing, making it even more difficult for the inspector to hear them.

[0008] On the other hand, in the soapy water test, the swelling and initial pressure due to a small amount of fluid leakage from the valve seat surface were detected. to Therefore, it is not possible to distinguish between the swelling caused by a small amount of fluid outflow and the swelling caused by a small amount of fluid outflow, and it is not possible to obtain an accurate starting pressure.

[0009] In the method described in Patent Document 1, when a high-pressure safety valve begins to blow, the sound pressure is low and the vibration is small, making it difficult to detect such small vibrations, making accurate pressure measurement difficult.The method described in Patent Document 2 increases the internal pressure of the safety valve in stages, which takes a very long time for inspection and is not practical.The method described in Patent Document 3 makes it difficult to distinguish between a safety valve leak and the start of blowing, and if the speed of pressure increase inside the safety valve is slowed down, a leak will also be detected, making accurate pressure measurement difficult.

[0010] Therefore, an object of the present invention is to provide a method and apparatus for measuring a set pressure accurately and without variation, which can more reliably ensure the safety of equipment and containers. [Means for solving the problem]

[0011] The present invention provides a method for measuring the operating pressure of a safety valve, the method comprising the steps of supplying a pressurized fluid to a safety valve to be measured, acquiring a pressure value of the supplied fluid, acquiring an operating sound generated when the safety valve is operated, and linking the generation of the operating sound and the pressure value via time to determine the pressure value at the time the operating sound was generated as the operating pressure value of the safety valve.

[0012] In one embodiment, the method includes the steps of: determining frequency components of the acquired operating sound; and detecting, from the frequency components, a specific frequency that occurs when fluid flows out from between the valve body and the valve seat of the safety valve. The time at which the specific frequency is detected is the time at which the operating sound occurs, and the operating pressure value is the blow-start pressure value of the safety valve.

[0013] In one embodiment, the specific frequency is a frequency specific to the safety valve.Preferably, the method further comprises the step of determining the specific frequency.

[0014] In one embodiment, the step of determining the specific frequency further includes supplying a pressurized fluid to the safety valve and acquiring a pressure value of the supplied fluid. This step further includes acquiring a pre-activation sound, which is a sound made before the safety valve is activated, and acquiring an activation sound generated when the safety valve is activated. By comparing a signal generated from the pre-activation sound with a signal generated from the activation sound, the frequency of the activation sound is determined as the specific frequency.

[0015] The method further includes the steps of: determining the frequency of the operating sound as the specific frequency, finding a change interval from a signal intensity not including the specific frequency component to a signal intensity including the specific frequency component, and determining that the operating sound including the specific frequency component has occurred in the change interval. In one embodiment, the occurrence time of the operating sound may be a time corresponding to a position of ¼ of the amplitude height of the change interval.

[0016] In another embodiment, the operating pressure value is a blow-off pressure value of the safety valve. The time of occurrence of the maximum operating sound is the time of occurrence of the operating sound.

[0017] In another aspect, the present invention provides an apparatus for measuring the operating pressure of a safety valve, the apparatus including: a fluid supply unit that supplies pressurized fluid to a safety valve to be measured; a pressure measurement unit that measures the pressure of the supplied fluid; an operating sound acquisition unit that acquires operating sound generated when the safety valve is activated; and a computer that links the occurrence of the operating sound acquired by the operating sound acquisition unit with the pressure value measured by the pressure measurement unit via time, thereby determining the pressure value at the time the operating sound occurred as the operating pressure value of the safety valve. [Effects of the Invention]

[0018] According to the present invention, by digitizing the measurement of the start pressure and discharge pressure in the inspection of a safety valve, it is possible to obtain reproducible, objective and reliable pressure values ​​without variation or error, without being dependent on the level of ambient noise, the skill of the inspector or subjective judgment.

[0019] In particular, the sound pressure of the operating sound caused by the initial blow pressure is small, making it difficult to measure by listening. However, according to the present invention, by detecting the occurrence of a specific frequency contained in the operating sound even with a small sound pressure, the initial blow pressure can be accurately determined from the time when the specific frequency occurs.

[0020] Conventional acoustic testing has been used to inspect safety valves in high-pressure environments (over 90 MPa) that correspond to the initial pressure at which the valve begins to blow. However, acoustic testing by workers is dangerous because it involves the risk of leakage from joints due to the reaction force when the safety valve is activated. However, with this invention, there is no need for workers to wait near the safety valve, making it possible to perform inspections with a high degree of safety. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a block diagram showing the configuration of a safety valve actuation pressure measuring device according to an embodiment of the present invention; [Figure 2] 1 is a flow chart illustrating a method for measuring a safety valve operating pressure according to an embodiment of the present invention. [Figure 3] FIG. 10 is a flow chart for determining a specific frequency of the sound generated when the safety valve starts to blow. [Figure 4] FIG. 10 is a block diagram showing the configuration of a safety valve actuation pressure measuring device according to another embodiment of the present invention. [Figure 5] FIG. 4 is a flow chart illustrating a method for measuring a safety valve operating pressure according to another embodiment of the present invention. [Figure 6] 10 shows the screen display when a specific frequency is determined for a specific safety valve. [Figure 7] 10 shows a screen display showing the occurrence of a particular frequency when the set pressure is changed in a particular safety valve. [Figure 8]10 is a graph showing the results of processing performed to enable a comparison between the time a trigger signal is generated and the inlet pressure of the safety valve at that time when the pressure at which the safety valve starts to blow is measured. [Figure 9] 1 is a graph showing the results of processing performed when measuring the blow-out pressure of a safety valve so that the time when the blow-out operation sound occurs can be compared with the inlet side pressure of the safety valve at that time. DETAILED DESCRIPTION OF THE INVENTION

[0022] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0023] 1. Problems with conventional testing methods The Japanese Industrial Standard JIS B8210 specifies the product standard for safety valves. A safety valve is a valve that does not rely on any external power other than the pressure of the fluid being used, and is designed to automatically release a predetermined amount of fluid to prevent the set pressure from being exceeded, and to automatically close after the pressure has returned to normal operating conditions. The set pressure is the pressure at which the safety valve begins to open.

[0024] According to the Japanese Industrial Standards, as mentioned above, two methods are specified for checking the starting pressure of gas and liquid safety valves: the acoustic method and the soap film method. If the pressure confirmed by these methods is the same as the set pressure, the safety valve is deemed to open at the set pressure and can be deemed to have passed the inspection. However, the applicant believes that these confirmation methods have the following problems.

[0025] (Problems with the auditory confirmation method) The acoustic confirmation method involves the inspector listening to the sound of fluid flowing out (sound when operating) when the blowing begins. (1) When the set pressure of the safety valve is high, the force of the spring that presses the valve body increases, so the lift of the safety valve becomes structurally small. A small lift reduces the amount of fluid that flows out, and the sound pressure also decreases accordingly. Therefore, the operating sound generated at the start of blowing pressure becomes very quiet and difficult to hear.

[0026] (2) When the ambient noise level in the testing environment is high, the sound of the fluid flowing out at the start of blowing is buried in the background noise, making it difficult to hear the sound accurately.

[0027] (3) Since confirmation by listening relies on the inspector's subjective judgment, the results are prone to variability and lack reliability and reproducibility.

[0028] (4) From the viewpoint of safety, inspectors must maintain a certain distance from the test specimen during sound measurement. However, by increasing the distance from the sound source, the sound pressure decreases, making it more difficult to hear the sound when the test specimen starts to blow.

[0029] (5) When checking by listening, the results lack objectivity because there are individual differences in the speed of reaction to sounds and judgment ability of each inspector.

[0030] (6) The reaction time from detecting the sound of the fluid flowing out at the start of blowing (for example, a whoosh) to reading the pressure varies depending on the inspector. Therefore, there are differences in the timing of detecting the sound pressure, which causes variations in the results.

[0031] (7) Normally, it takes at least 0.25 seconds from the time the sound of operation is heard until the pressure gauge reading is read. Due to this delay, the pressure reading read by the inspector differs from the actual starting pressure and lacks accuracy.

[0032] (8) During the safety valve operation performance inspection, the safety valve may suddenly operate and emit a loud noise, so inspectors are required to wear hearing protection such as earplugs or receivers. With such protection, it becomes difficult to accurately detect the operation sound.

[0033] (9) In recent years, the set pressure of gas safety valves has been increasing, with ultra-high pressure settings of 90 MPa required for safety valves at hydrogen stations and 120 MPa required for hot isostatic pressing (HIP) equipment. During these ultra-high pressure operation tests, the testing equipment must be covered with a polycarbonate safety fence to ensure the safety of inspectors, but this safety fence reflects, attenuates, and blocks sound, making it even more difficult to detect the sound when the valve is operating.

[0034] (Problems with the soapy water film method) The soapy water film check is a method of checking for minute outflows from the valve seat by observing the swelling of the soapy water film on the outlet side of the safety valve. The swelling of the film can be due to leakage from the valve seat or to a minute outflow of fluid that occurs when the initial pressure is reached. In either case, the soapy water film swells, making it difficult to distinguish between the two. Regarding this point, JIS B8210 allows a certain amount of leakage at 90% of the set pressure for metal valve seat surfaces. Therefore, the soapy water film can swell due to allowable leakage even before the initial pressure is reached. Therefore, the method of determining the arrival of the initial pressure by observing the swelling of the soapy water film cannot distinguish between a swell due to leakage and a swell due to the initial pressure, resulting in an inaccurate detection of the initial pressure.

[0035] 2.Method and device for measuring the operating pressure of a safety valve The present invention provides a method and apparatus for measuring the operating pressure of a safety valve. As described above, safety valves are inspected by measuring either the opening pressure or the outlet pressure, and if the measured opening pressure is the same as the set pressure, the safety valve is deemed to have passed the inspection. In the method for measuring the operating pressure, a fluid is supplied to the safety valve to be measured. If the fluid is a gas or liquid, the opening pressure is measured, and if the fluid is steam, the outlet pressure is measured.

[0036] The pressure value of the fluid supplied to the safety valve is acquired using an appropriate pressure sensor. The acquired pressure value is the pressure of the fluid at the inlet side of the safety valve. The pressure value of the fluid supplied to the safety valve and the time at which the pressure value occurs are continuously acquired in real time.

[0037] When a fluid is supplied to the safety valve and the safety valve operates, an operating sound is generated. In the case of measuring the initial pressure, the operating sound is the sound of the fluid flowing out when the pressure on the inlet side of the safety valve rises and a small amount of fluid is detected flowing out from the outlet side, and in the case of measuring the outlet pressure, it is the sound of the fluid flowing out when the safety valve pops, i.e., when it rapidly opens and continuously discharges the internal fluid.

[0038] Since the pressure value of the fluid supplied to the safety valve and the time at which that pressure value was displayed are known, by determining the time at which the operating sound occurred and identifying the pressure value of the fluid at that time, it is possible to determine that this pressure value is the pressure value at which the safety valve operated. In other words, by linking the generation of the operating sound and the pressure value via time, the pressure value at the time at which the operating sound occurred can be determined as the operating pressure value of the safety valve.

[0039] Regarding the blow-on pressure, the valve disc lift amount at the blow-on pressure is very small, so the amplitude of the operating sound generated during the lift is small, and therefore the sound pressure is low. Therefore, it is difficult to accurately measure the sound pressure of the operating sound during the blow-on pressure. The applicant of this application discovered that when a safety valve begins to blow, a specific frequency is generated by the outflow of fluid due to the pressure difference between the inlet side and the outlet side (atmosphere). This specific frequency is generated when high-pressure fluid flows through a narrow lift gap (gap). By identifying the time when the specific frequency occurs and identifying the pressure value on the inlet side of the safety valve at that time, i.e., by linking the generation of the specific frequency (generation of the operating sound) with the pressure value via time, the blow-on pressure can be accurately determined. Before the valve disc lifts, leakage may occur due to minute scratches or surface roughness on the valve seat and valve disc. In such cases, the specific frequency is not generated.

[0040] On the other hand, regarding the blow-out pressure, the blow-out of a safety valve is a loud noise that occurs when the inlet pressure is instantly released. Because the sound pressure of the operating sound is high (for example, 70 to 80 dB or more), even in a noisy factory, by identifying the operating sound picked up by a microphone or the like and identifying the pressure value on the inlet side of the safety valve at that time, in other words, by linking the generation of the operating sound with the pressure value via time, the blow-out pressure can be accurately determined.

[0041] 2-1. Measurement of starting pressure The detailed method for measuring the blow-onset pressure is explained below. Figure 1 is a block diagram showing the configuration of the device for measuring the blow-onset pressure of a safety valve, and Figure 2 is a flow diagram showing the method for measuring the blow-onset pressure of a safety valve. This measurement method involves using a microphone to capture the pre-operation sound, which is the sound before the safety valve starts to blow, and the operating sound, which is generated when the valve starts to blow. A mixed-signal oscilloscope (MSO) is used to perform mixed-domain analysis of the captured pre-operation sound and operating sound, and the occurrence of a specific frequency contained in the operating sound is used as a trigger. The occurrence of the trigger is linked to the pressure value at that time, and this pressure value is determined as the blow-onset pressure.

[0042] (1) Measuring device configuration The components and functions of the device shown in FIG. 1 are as follows: Compressor 1: Accumulator of fluid supplied to buffer tank 2 Buffer tank 2: Temporary storage of fluid Adjustment valve 3: Pressure control Flow control metering valve 4: Adjusts the pressure from buffer tank 2 so that the pressure of the safety valve gradually increases Pressure sensor 5: Measuring fluid pressure Safety valve 6: Measurement object Microphone 7: Sound capture around the safety valve MSO (Mixed Signal Oscilloscope) 8: Mixed-domain analysis of the signal from microphone 7 Trigger signal converter 9: Converts the 100ns pulse wave (trigger signal) from the MSO to DC5V after detection. Pressure gauge 10: Visual monitoring of rising pressure of pressure sensor 5 (for double checking) Blow valve 11: Pressure release PC-controlled strain gauge 12: Detects signals from the pressure sensor 5 and trigger signal converter 9, and acquires the time of each pressure and trigger signal. Personal computer 13: Receives data from the PC controller type strain measuring device 12, creates and displays time-pressure graphs and time-trigger signal graphs, and identifies digital values.

[0043] (2) determining a trigger that indicates the occurrence of a specific frequency contained in the sound when activated; In the method for measuring the onset pressure, before measuring the onset pressure in an actual test, a "specific frequency" is searched for, which is a specific frequency of the operating sound generated by the outflow of fluid due to the pressure difference between the inlet and outlet (atmosphere) sides when the safety valve begins to blow, and a trigger indicating its occurrence is determined. Figure 3 is a flow chart showing the method for searching for the specific frequency and determining the trigger. The specific frequency is a unique value determined by the type, valve seat diameter, and size (nominal diameter) of the safety valve. The device for searching for the specific frequency and determining the trigger can be a device equipped with the same equipment as that shown in Figure 1. However, since the purpose here is not to determine the pressure at which the onset sound occurs, it is not necessary to use the pressure sensor 5, trigger signal converter 9, pressure gauge 10, PC-controlled strain gauge 12, and personal computer 13 shown in the device shown in Figure 1.

[0044] (a) Pressure accumulation by the compressor and operation of the safety valve The compressor 1 is started, and fluid at a pressure higher than the set pressure of the safety valve 6 to be inspected is stored in the buffer tank 2 (S31 in FIG. 3). Next, the adjustment valve 3 is opened, and the fluid is supplied to the metering valve 4. While the boosted flow rate is adjusted by the metering valve 4, the safety valve 6 for determining the specific frequency is operated (S31). The sound around the safety valve 6 before and after the start of blowing is picked up by the microphone 7. It is preferable that the distance between the safety valve 6 and the microphone 7 is set to a distance at which the signal strength of the specific frequency is sufficiently large.

[0045] (b) Acquisition of the sound when the instrument starts to blow using a microphone and search for specific frequencies The sound signal picked up by the microphone 7 is sent to the MSO 8, and mixed-domain analysis is used to generate data representing the relationship between time, the frequency components contained in the sound, and the signal strength (S32), and the sound before the start of blowing (pre-operation sound) is compared with the sound at the start of blowing (operation sound).

[0046] The mixed-domain analysis used in this method, which can typically be performed using an MSO8, is a technique that enables simultaneous analysis of the time domain and the frequency domain. A typical oscilloscope displays the relationship between time and sound pressure, but this display makes it difficult to identify the occurrence of specific frequencies (here, the frequency of the operating sound). However, to identify the specific frequency of the operating sound at the beginning of playing, it is necessary to understand the relationship between time and the signal strength for each frequency of the acquired operating sound. To do this, it is necessary to use mixed-domain analysis, which can track fluctuations in signal strength in specific frequency bands and accurately capture the occurrence timing of specific frequencies of the operating sound at the beginning of playing. Mixed-domain analysis and mixed-signal oscilloscopes used in this invention are well known to those skilled in the art, so they will not be described in detail here.

[0047] Using mixed-domain analysis and the MSO 8 having these characteristics, it is possible to capture the time change in signal strength corresponding to a specific frequency component from the pre-activation sound and activation sound acquired by the microphone 7. More specifically, by comparing the signal generated from the pre-activation sound (not including the specific frequency) with the signal generated from the activation sound (including the specific frequency), the frequency contained in the activation sound is searched for and determined as the specific frequency, and a change interval (rising point in signal strength) from the signal strength not including the specific frequency component to the signal strength including the specific frequency component is found (S34). It is possible to determine that the activation sound including the specific frequency component occurred during this change interval.

[0048] (c) Setting a trigger that indicates the occurrence of a specific frequency The frequency and intensity of the sound transmitted to the MSO8 change over a time interval before and after the generation of the activation sound. Therefore, the timing (time) of generating a trigger signal indicating the generation of a specific frequency is arbitrarily set as any position from the start of the change to the completion of the change (the change interval of the signal intensity corresponding to the specific frequency component) (S35). Before the start of the change, the frequency components and their signal intensity are included in the pre-activation sound (i.e., the specific frequency is not included), and after the completion of the change, the frequency components and their signal intensity are included in the activation sound.

[0049] The timing for generating the trigger signal can be set at any point within the frequency change interval. If the timing for generating the trigger signal is set at a point where the amplitude is too low or too high, there is a risk of falsely determining that a specific frequency has occurred even when unwanted ambient noise is present. Therefore, it is preferable to set the timing for generating the trigger signal while taking into consideration the risk of false determination. In one embodiment, the timing for generating the trigger signal can be set at the lower quarter of the amplitude from the start to the end of the frequency change. By setting the timing for generating the trigger signal closer to the start of the frequency change, the time difference between the start of the rising edge and the generation of the trigger signal can be reduced. In another embodiment, the timing for generating the trigger signal can be set, for example, to the center of the frequency change interval (half the amplitude). The MSO 8 generates and transmits the trigger signal at the timing for the occurrence of the specific frequency determined in this manner.

[0050] (d) Setting the center frequency and resolution bandwidth (RBW) Even if a difference is found between the presence and absence of the operating sound at the beginning of playing, if the onset of the specific frequency change is not clear, it is preferable to set the resolution bandwidth (RBW) so that the frequency band where the difference appears is included (S33). For example, if it is found that the difference in sound intensity is significant around 1.25 kHz to 3.5 kHz, it is preferable to set the RBW with a center frequency of one of these frequencies so that it includes 1.25 kHz and 3.5 kHz. The reason for setting the RBW is to exclude from the measurement range a frequency range that is clearly different from the frequency of the operating sound at the beginning of playing, thereby enabling clear recognition of the onset of the signal intensity corresponding to the specific frequency component contained in the operating sound. If the RBW width is set too narrow, the onset may fall outside the range, while if the RBW width is set too wide, the onset may become unclear. By appropriately setting the RBW, it is possible to more clearly identify the change in signal intensity corresponding to the specific frequency component.

[0051] (e) Specific frequencies As mentioned above, the specific frequency is a unique value determined by the type, valve seat diameter, and size (nominal diameter) of the safety valve. In other words, when inspecting the set pressure of a safety valve with the same conditions, the specific frequency of the operating sound at the start of blowing will be the same even if the set pressure is different, so (2) "the process of determining the trigger that indicates the occurrence of the specific frequency contained in the operating sound" can be omitted.

[0052] The reason why safety valves with the same model, valve seat diameter, and size (nominal diameter) have the same specific frequency is thought to be as follows: The starting pressure of a safety valve is determined by the force of the safety valve's spring. Tightening the spring increases the starting pressure, and loosening it decreases it. Tightening the spring reduces the valve disc lift, and conversely, loosening the spring increases the valve disc lift. In other words, a safety valve with a larger P1 (starting pressure) set has a smaller lift because the spring is tightly fastened, and a safety valve with a smaller P1 set has a larger lift because the spring is loosely fastened. Here, the flow rate of fluid passing through the narrow gap on the seal surface is calculated using the following formula (1): Q ∝ h n (P1-P2) (1) It is expressed as follows. Q is the flow rate, h is the lift amount (gap height), P1 is the starting pressure, and P2 is atmospheric pressure. If the safety valve model, valve seat diameter, and size are the same, the lift amount h changes in the direction that cancels out the change in the starting pressure P1, so the flow rate Q at the seal surface will be the same. If the flow rate Q at the seal surface is the same, the specific frequency of the sound when the valve starts to blow will not change. Therefore, the specific frequency is a unique value determined by the safety valve model, valve seat diameter, and size (nominal diameter).

[0053] (3) Measurement process of starting pressure An actual inspection is carried out for the safety valve whose specific frequency of the sound when it operates at the initial pressure has been identified in (2) above. For the actual inspection, an apparatus having the configuration shown in Figure 1 is used. In the actual inspection, first, 2 )(a) "Accumulating pressure by the compressor and activating the safety valve" is performed (S21 in Figure 2).

[0054] The pressure sensor 5 continuously measures the pressure rise of the safety valve (S22). Simultaneously, the pressure rise is preferably monitored visually using the pressure gauge 10. The measured pressure value is transmitted to the PC-controlled strain measurement instrument 12. The pre-operation sound before the safety valve 6 begins to blow and the operating sound when the valve starts to blow are also transmitted to the MSO 8. The MSO 8 determines the frequency components of the pre-operation sound and the operating sound (S23). When the MSO 8 detects a specific frequency from the determined frequency components (S23), it generates a trigger signal indicating the occurrence of the specific frequency and transmits the generated trigger signal from the MSO 8 to the PC-controlled strain measurement instrument 12 (S24). If the pulse width of the trigger signal is small, it is preferable to convert the trigger signal by the trigger signal converter 9 into a signal that can be detected by the PC-controlled strain measurement instrument 12. In this way, a trigger signal is generated when a specific frequency is detected. At the same time, the pressure value at that timing is linked via time, as described below, to measure the blow-start pressure in real time.

[0055] In this embodiment, a strain pressure gauge is used instead of a pressure gauge that can output the measured pressure value as digital data, and therefore a strain measuring instrument that can convert the measurement value (analog data) from the pressure gauge into digital data is used. If a pressure gauge equipped with a pressure sensor and a strain gauge that can output the measured pressure value as digital data can be used, there is no need to send the pressure value (digital data) to the strain measuring instrument, and it can be sent directly to a computer.

[0056] The PC-controlled strain measurement device 12 detects the pressure value from the pressure sensor 5 and the trigger signal from the trigger signal converter 9, and acquires the respective times (S25). The detected pressure value and trigger signal and their times are sent to the personal computer 13, and data is processed so that the time when a specific frequency was generated and the pressure value (pressure on the inlet side of the safety valve) at that time can be identified, that is, so that the generation of the sound at the start of blowing and the pressure value are linked via time. This pressure value is identified as the blowing start pressure of the safety valve (S26). If the pressure value measured in this way is the same as the set pressure of the safety valve, it can be confirmed that this safety valve is a safety valve that opens at the set pressure.

[0057] 2-2. Measurement of blowout pressure The detailed method for measuring the blowout pressure is explained below. Figure 4 is a block diagram showing the configuration of a device for measuring the blowout pressure of a safety valve, and Figure 5 is a flow diagram showing the method for measuring the blowout pressure of a safety valve. This measurement method is characterized by acquiring the operating sound generated when the safety valve blows out as digital data, and linking the occurrence of the operating sound with the pressure value at that time to determine that pressure value as the blowout pressure.

[0058] (1) Measuring device configuration The components and functions of the device shown in FIG. 4 are as follows: Compressor 1: Accumulator of fluid supplied to tank 2 Pressure storage tank 2: Temporary storage of fluid Adjustment valve 3: Adjusts the pressure from the tank to gradually increase the pressure of the safety valve Pressure sensor 4: Measures fluid pressure Safety valve 5: Measurement object Digital sound level meter 6: Acquisition of sound generated from safety valve Pressure gauge 7: Visual monitoring of rising pressure of pressure sensor 4 (for double checking) Blow valve 8: Pressure release PC controller type strain measurement device 9: Detects signals from pressure sensor 4 and digital sound level meter 6, and observes the relationship between pressure and sound pressure signals Personal computer 10: Receives data from the PC controller type strain measuring instrument 9, creates and displays time-pressure graphs and time-sound pressure graphs, and identifies digital values

[0059] (2) Measurement process of blowing pressure The measurement of the blowing pressure is carried out as follows. The compressor 1 is started, and a fluid at a pressure higher than the set pressure of the safety valve 5 to be inspected is stored in the tank 2 (S51 in FIG. 5). Next, the adjustment valve 3 is operated to gradually supply the fluid from the tank 2 into the inside of the safety valve 5, thereby increasing the pressure inside the safety valve 5. This pressure increase is continuously measured by the pressure sensor 4 (S52). At the same time, the pressure increase is visually monitored by the pressure gauge 7. In this process, before the blowing operation, the sound pressure acquired by the digital sound level meter 6 indicates zero.

[0060] When the safety valve 5 starts to blow (S51), the sound pressure measured by the digital sound level meter 6 rises sharply, and at the same time the pressure inside the safety valve 5 drops. At this time, accurate waveform information can be obtained by adjusting the vertical sensitivity of the digital sound level meter 6 to an amplitude that makes the entire sound pressure waveform easily visible, and by adjusting the sweep time appropriately. The distance between the digital sound level meter 6 and the safety valve 5 is preferably set to a distance that allows the sound pressure of the blowing sound from the safety valve 5 to be sufficiently large.

[0061] Information on when the blowing operation occurs, i.e., both the pressure value from the pressure sensor 4 and the sound pressure value from the digital sound level meter 6, are sent to the PC controller type strain measurement instrument 9, and the respective times are acquired (S54). The reason for using the PC controller type strain measurement instrument 9 is as described above in the explanation of the blowing start pressure. The pressure value and sound pressure value at each time are sent from the PC controller type strain measurement instrument 9 to the personal computer 10. The personal computer 10 creates a graph showing the pressure change over time and a graph showing the sound pressure change over time.

[0062] By identifying the time when the peak sound pressure occurs during blowing and the pressure value at that time, i.e., by linking the generation of sound during blowing operation and the pressure value via time, the blowing pressure value can be accurately determined (S55). The blowing pressure can be accurately identified, for example, by the following procedure. (a) On the graph of sound pressure changes displayed on the monitor of the personal computer 10, the cursor is moved to the peak value of the sound pressure. (b) The cursor position is linked in time with the graph of pressure change, and the pressure value at the time when the peak sound pressure occurs where the cursor is positioned is displayed on the screen of the personal computer 10. If the pressure value measured in this way is the same as the set pressure of the safety valve, it can be confirmed that this safety valve is a safety valve that opens at the set pressure.

[0063] As described above, according to the present invention, by utilizing clear physical phenomena such as specific frequencies and sound pressure peaks that occur when the safety valve starts to blow and when it starts to blow, it is possible to eliminate the reading errors and ambiguity of judgment that are inherent in analog systems. As a result, according to the present invention, it is possible to specify the starting pressure and the blow-out pressure of the safety valve as objective and highly accurate digital values, and it has the excellent effect of significantly improving the reliability, reproducibility, and efficiency of the measurement work. [Example]

[0064] (Example 1: Identifying a specific frequency and determining the timing of generating a trigger signal indicating its occurrence) Here, we will explain an example in which a specific frequency was actually identified using the method shown in Figure 3 and the timing for generating a trigger signal was determined. The device used was the same as the configuration shown in Figure 1, except that the pressure sensor 5, trigger signal converter 9, pressure gauge 10, PC-controlled strain gauge 12, and personal computer 13 were removed. The specifications and conditions for each component device were as follows: The fluid supplied to the safety valve was nitrogen gas; the buffer tank and adjustment valve were general-purpose products. Compressor 1: Design pressure 160MPa Flow control metering valve 4: Butech, model 60MMV46, set pressure 400MPa, size 1 / 4" HP Safety valve 6: Takei Manufacturing Co., Ltd., model AA01270UHCG-NP, diameter 3 mm, thread size 1 1 / 8, set pressure 73 MPa, lift 0.2 mm Microphone 7: Audio-Technica ATR1100x dynamic microphone MSO8: Tektronix, model number MS044B (200 MHz bandwidth, 4 channels)

[0065] The actual process was as follows. Figure 6 shows the actual data display screen of the MSO8 measured when determining the specific frequency. First, the sound before and after the safety valve was activated was captured by microphone 7, and the captured data was input into the MSO8. Next, the frequency range span of the MOS8 was adjusted appropriately to search for level differences in the safety valve signal strength in the waveform data showing the signal strength of the composite wave over the set frequency range. Figure 6(a) shows the data display screen of the activation sound before the sound at the beginning of blowing was generated, in which the sound signal captured by microphone 7 was analyzed using mixed-domain analysis in the MSO8. Figure 6(b) shows the data display screen of the activation sound after the sound at the beginning of blowing was generated, analyzed in the same way. In each screen, the middle waveform of the three waveforms on the left half of the screen (hereinafter referred to as "Waveform Data 1") is a waveform with time on the horizontal axis and the signal strength of the composite wave over the set frequency range on the vertical axis. The waveform in the lower right half of the screen (hereinafter referred to as "waveform data 2") is a waveform with the horizontal axis representing frequency within a set frequency range and the vertical axis representing signal strength, and the upper right half (hereinafter referred to as "waveform data 3") is data in which the height and density of frequency versus time on the horizontal axis are expressed in color.

[0066] Comparing Figures 6(a) and 6(b), we searched for the frequency band in which the level difference between the two appears in Waveform Data 1. From Waveform Data 2 and Waveform Data 3, we found that the level difference appears in the frequency band including 1.25 kHz to 3.5 kHz, and that a frequency of approximately 3.5 kHz is a specific frequency contained in the operating sound. Next, we set the resolution bandwidth (RBW) to a center frequency of 3.5 kHz so that the frequencies from 1.25 kHz to 3.5 kHz would be included. The resulting data display screen is shown in Figure 6(c). As can be seen from Waveform Data 1, a portion (a change section) was discovered where the signal strength of the composite wave containing frequency components from 1 to 3.5 kHz rises significantly over a certain time interval. This rising portion is the point at which the operating sound occurs.

[0067] In this embodiment, the timing at which a specific frequency occurs was set to the point where ¼ of the amplitude from the start of the rising edge to the end of the rising edge was reached based on waveform data 1 in Fig. 6(c). The start of the rising edge was the signal strength of the sound when no operating sound was being generated, i.e., the pre-operating sound having a frequency of 1 kHz, and the end of the rising edge was the signal strength of the sound when the operating sound was being generated, i.e., the operating sound having a frequency of approximately 3.5 kHz.

[0068] (Example 2: Specific frequency when the set pressure of the blow-start pressure is changed) It was confirmed that the specific frequency inherent to the sound produced when the safety valve starts blowing does not change if the type, valve seat diameter, and size of the safety valve are the same. A safety valve of the same type, valve seat diameter, and size as the safety valve used in Example 1 was used with a set pressure of 65 MPa, 70 MPa, 80 MPa, and 91 MPa, and the specific frequency was determined for each set pressure in the same manner as in Example 1. Figures 7(a) to (d) show the screens of the MSO8 used to determine the specific frequency for each set pressure (65 MPa, 70 MPa, 80 MPa, and 91 MPa). Comparing the screens in Figure 7, the specific frequency of the sound produced when the safety valve starts blowing was approximately 3.5 kHz for all set pressures.

[0069] (Example 3: Measurement of blowing start pressure) The blow-start pressure of the safety valve having the specific frequency determined in Example 1 was measured by the method shown in Figure 2. The device used had the configuration shown in Figure 1. The specifications and conditions of each component device were as follows. The fluid supplied to the safety valve was nitrogen gas. General-purpose buffer tanks, adjustment valves, pressure gauges, and blow valves were used. Compressor 1: Design pressure 160MPa Flow control metering valve 4: Butech, model 60MMV46, set pressure 400MPa, size 1 / 4" HP Pressure sensor 5: Tokyo Measuring Instruments Laboratory Co., Ltd., model PWH-PA, capacity 150MP Safety valve 6: Takei Manufacturing Co., Ltd., model AA01270UHCG-NP, diameter 3 mm, thread size 1 1 / 8, set pressure 73 MPa, lift 0.2 mm Microphone 7: Audio-technica, model ATR1100x MSO8: Tektronix, model number MS044B (200 MHz bandwidth, 4 channels) PC-controlled strain measuring instrument 12: Tokyo Measuring Instruments Laboratory Co., Ltd., model DC-004P

[0070] FIG. 8 is a graph showing the results of processing the pressure value from the pressure sensor 5 sent from the PC-controlled strain measurement device 12 to the personal computer 13 and the trigger signal from the trigger signal converter 9 so that the time at which the trigger signal is generated can be compared with the inlet pressure of the safety valve at that time. The bottom graph in FIG. 8 is a graph with time on the horizontal axis and the trigger signal value on the vertical axis, and the middle graph is a graph with time on the horizontal axis and the pressure value on the vertical axis. The time on the horizontal axis of both graphs represents the same time. The top table in FIG. 8 is a table showing the trigger signal value and pressure value at the same time. In this example, the same safety valve as in Example 1 is used, so the trigger signal is generated when a specific frequency of approximately 3.5 kHz is detected, and the trigger signal is generated when the operating sound is generated.

[0071] From Figure 8, it is possible to confirm the pressure value at the time when the trigger signal was generated. In this example, the pressure on the inlet side of the safety valve when the trigger signal was generated was 73.06 MPa, as shown in the table at the top of Figure 8. Since the set pressure of this safety valve 6 was 73 MPa as described above, it was confirmed that the safety valve 6 opened at the set pressure. In addition, the error between the set pressure and the measured pressure was 0.082%.

[0072] (Example 4: Measurement of blowing pressure) The blow-off pressure was measured using the method shown in Figure 5. The equipment used had the configuration shown in Figure 4. The specifications and conditions for each component device were as follows: The fluid supplied to the safety valve was steam. General-purpose pressure storage tanks, adjustment valves, pressure gauges, and blow-off valves were used. Compressor 1: Design pressure 50MPa Pressure sensor 4: Tokyo Measuring Instruments Laboratory Co., Ltd., model PW-20MPA, capacity 20MPa Safety valve 5: Made by Ben Co., Ltd., model SL-8, diameter 15A, thread size 1 / 2, set pressure 2.15MPa Digital sound level meter 6: Trusco Nakayama Corporation, model TSL-1320 PC-controlled strain measuring instrument 9: Tokyo Measuring Instruments Laboratory Co., Ltd., model DC-004P

[0073] FIG. 9 shows graphs obtained by processing the pressure values ​​from the pressure sensor 4 and the sound pressure values ​​from the digital sound level meter 6 sent from the PC-controlled strain measurement device 9 to the personal computer 10 so that the time when the sound occurred during blow-out operation can be compared with the inlet pressure of the safety valve at that time. The lower graph in FIG. 9 is a graph with time on the horizontal axis and sound pressure on the vertical axis, while the upper graph is a graph with time on the horizontal axis and pressure value on the vertical axis. The time on the horizontal axis of both graphs represents the same time. From these graphs, the pressure value at the time when the sound pressure peak occurred can be confirmed. In this example, the pressure on the inlet side of the safety valve when the sound pressure peak occurred was 2.15 MPa. Since the set pressure of this safety valve 5 was 2.15 MPa as described above, it was confirmed that the safety valve 5 opened at the set pressure.

Claims

1. 1. A method for measuring the operating pressure of a safety valve, comprising: supplying a pressurized fluid to a safety valve to be measured; obtaining a pressure value of the fluid being delivered; acquiring an operating sound generated when the safety valve is operated; A step of determining a frequency component of the acquired operating sound; detecting a specific frequency generated when fluid flows out from between a valve body and a valve seat of the safety valve from the frequency components; determining the pressure value at the time when the operating sound occurred as the operating pressure value of the safety valve by linking the generation of the operating sound and the pressure value via time; Including, The time when the specific frequency is detected is the time when the operating sound is generated, and the operating pressure value is the blow start pressure value of the safety valve. method.

2. the specific frequency is a frequency specific to the safety valve, further comprising the step of determining the specific frequency. The method of claim 1.

3. The step of determining the specific frequency includes: providing pressurized fluid to the relief valve; obtaining a pressure value of the fluid being supplied; Acquiring a pre-activation sound that is a sound that occurs before the safety valve is activated; Acquiring an operating sound generated when the safety valve is operated; determining a frequency of the activation sound as the specific frequency by comparing a signal generated from the pre-activation sound with a signal generated from the activation sound; The method of claim 2 , comprising:

4. After determining the frequency of the operating sound as the specific frequency, Finding a transition section from a signal intensity not including the specific frequency component to a signal intensity including the specific frequency component; determining that the operating sound including the specific frequency component has occurred in the change section; The method of claim 3, comprising:

5. The time when the operating sound is generated corresponds to a position of ¼ of the amplitude height of the change section. The method of claim 4.

6. A device for measuring the operating pressure of a safety valve, a fluid supply unit that supplies a pressurized fluid to the safety valve to be measured; a pressure measuring unit that measures the pressure of the supplied fluid; an operation sound acquisition unit that acquires an operation sound generated when the safety valve is activated; a detection unit that obtains frequency components of the acquired operating sound and detects, from the frequency components, a specific frequency that is unique to the safety valve and that is generated when fluid flows out from between the valve body and the valve seat of the safety valve; a computer that determines the pressure value at the time when the operating sound occurred as the operating pressure value of the safety valve by linking the occurrence of the operating sound acquired by the operating sound acquisition unit and the pressure value measured by the pressure measurement unit via time; Equipped with The time when the specific frequency is detected is the time when the operating sound is generated, and the operating pressure value is the blow-start pressure value of the safety valve. Device.

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