CN101666700B - Testing method of leakage rate of high-temperature sealing gasket and testing device thereof - Google Patents

Abstract

The invention relates to a testing method of the leakage rate of a high-temperature sealing gasket and a testing device thereof, which establishes the corresponding testing method of the leakage rate of the high-temperature sealing gasket. The testing method and the testing device thereof perfect the testing method of the leakage rate of the high-temperature gasket, have reasonable structure, ensure the high precision in measuring the pressure of a leakage detecting cavity, and overcome the problem of large experimental error because the leakage detecting cavity is not tightly sealed, so the leakage rate test of the high-temperature gasket can be realized easily. The structure of the leakage detecting cavity is improved, and the testing method of the leakage rate of the high-temperature gasket by using a low-pressure region as the leakage detecting cavity is established. The invention plays a positive role in researching the sealing performance of the high-temperature gasket and promoting the progress of the sealing technique, and well meets the requirements of the high-speed development of the modern industry for gasket sealing.

Description

Leakage rate of high-temperature sealing gasket method of testing and proving installation thereof

Technical field

The present invention relates to the test of pad elevated-temperature seal performance, the test unit through the design special construction proposes a kind of leakage rate of high-temperature sealing gasket method of testing and proving installation thereof.

Background technology

The equipment that the bolt flange gasket seal is widely used in process industrial is with during pipeline is connected, and pad is the key element that influence connects sealing property.The sealing of fluid is through closely contact each other between flange and pad, and the elastic-plastic deformation of dependence pad reduces or stops up leakage path, realizes with the increase resistance to flow.

Nearly three during the last ten years, and the sealing characteristics to the bolt flange syndeton has carried out research comparatively comprehensively both at home and abroad.This research field the richest achievement be exactly further investigation to gasket performance.As far back as 1974 the U.S. pressure vessel council (PVRC) bolt flange connect branch (S/C ON BFC) and begun the research of pad normal temperature performance, gasket factor m, y that ASME boiler and pressure vessel code are provided evaluate.Adopt ASTM (ASTM) standard; Asbestos pad and wound gasket normal temperature nitrogen and water test have been carried out; Research pad pretension stress and flange surface smooth finish are to the influence of sealing property, and the mutual relationship between m, y and gasket width, prefastening load, slip and the pressure medium.Proposed to comprise more widely " the pad test plan II " of milestone test and working condition tests afterwards again, as the basis that more effective standard design parameter and ASTM test standard are provided.Last the research of more than ten years, PVRC has had understanding more fully, the sealing property of measurable various prefastening loads and ambient operation condition lower gasket on experimental basis to the pad room-temperature property.States such as Germany, Austria have also carried out the research of pad normal temperature performance and corresponding rig for testing and measuring technology in succession.Compare with normal temperature, the seal failure problem under the worst hot case is more outstanding.High temperature cause pad aging, weightlessness, creep, lax, sealing property descends, and is the main cause that causes whole Flanged Connection System inefficacy.Owing to lack pad high-temperature behavior data, it still is experimental that the high temperature flange connects design at present, can't be to making correct man-rate at the labour connected system.

Nineteen eighty-two, the pad test has started pad high-temperature behavior project with high temperature switching performance research group (S/C ON GT&ETJB), has begun test and analytical work that a series of flange gaskets are connected high temperature circulation load lower seal performance.The high temperature performance of each web member of bolt flange pad and the sealing mechanism of connection have been inquired into; Studied factors and the relation between them that influences the connected system leakage and set up a series of methods for designing, made the slip of connected system under worst hot case reduce to minimum.

Bazergui, Marchand and Payne have developed pad heat aging test unit and hot compactedness device in 1988.Can do the creep relaxation test and the short-term leakage test of single test specimen respectively.They simulate actual operation operating mode, the characteristic of hot pad have been carried out the experimental study of system.Test findings shows: the acting in conjunction of temperature and pressure medium significantly descends the sealing property of pad, and the high temperature lower gasket produces creep and stress relaxation, and creep speed is much faster than normal temperature, thereby has reduced the pad compactedness.

Birembaut and the Bravo of France experimental study in 1988 high-temperature behavior of asbestos-packing gasket and asbestos spirally wound gasket.Test findings shows: the gasket compression amount increases with the increase of temperature; The pad slip raises with temperature and sharply increases; Slip reduces with the increase of pad prefastening load under the room temperature.This experimental study has disclosed the mechanical property and the sealing property of pad more all sidedly, but lacks the quantitative examination to its performance.

The BFC sub-committee of PVRC and high temperature design sub-committee constitute jointly a research group has set up the long-term hot performance research of pad in 1988 and 1989 test unit, have inquired into the influence of pad stress, creep and lax pair system compactedness.1998, people such as L Marchand developed the aging lax anchor clamps of a cover again, can carry out long-term ageing to gasket material, further study the long-term hot performance of pad.

The domestic Zhu Hong of Nanjing University of Technology life, Gu Baiqin etc. have carried out broad research from 1981 to the sealing mechanism of pad and the compactedness of bolt flange connected system.Developed multi-functional full-automatic gasket performance testing machine and pad high-temperature behavior test unit, gasket material performance test when being used for normal temperature and high temperature, and corresponding slip method of testing has been proposed.University of Petroleum is on the basis of the A that recommends with reference to U.S.'s ASTM F586-79 standard and U.S. PVRC, B test method; Gasket performance to patterns such as wound gasket, oil resisting paronite plate, metallic cover pad, anise and metal ellipses is studied; Obtain great number tested data, marked and drawed mechanics and sealing characteristics curve.On this basis, point out physical dimension, usable range, manufacturing requirement and the seal parameters value thereof of various pads, recommended the new method of joint seal of flanges design.

The develop rapidly of modern industry is more and more strict to the requirement of gasket seal, and be environmental protection, energy savings, the very urgent requirement of safety in production the serviceable life that reduces slip, prolongation seal element.Strict quantitatively control slip is the essential condition that guarantees modern system and equipment safety operation, the quantitative target that PVRC proposed slip in 1977, and recommending general industry slip index is 10 ^-3Cm ³/ s, to atomic energy and some chemical industry, the slip control indexes is 10 ^-7Cm ³Below/the s, when the device the slip amount of touching the mark can think the sealing lost efficacy.PVRC thinks also can be with lax 75% criterion as seal failure to initial load of bolt load.

Although the test of existing many high-temperature gasket sealing properties both at home and abroad; But also there is not perfect high-temperature gasket slip method of testing, existing pad elevated-temperature seal performance test apparatus, structure is outmoded; The cavity that leaks hunting is in the medium higher-pressure region; The measuring accuracy of cavity pressure of leaking hunting is low, and is easy to generate because the poorly sealed big problem of test error of bringing of cavity of leaking hunting the slip test difficulty of high-temperature gasket.

Summary of the invention

Technical matters to be solved by this invention is to design the low pressure to the high-temperature gasket experiments of sealing performance and leak hunting cavity as the leakage rate of high-temperature sealing gasket proving installation, and set up corresponding leakage rate of high-temperature sealing gasket method of testing.

The present invention takes following technical scheme to realize:

Leakage rate of high-temperature sealing gasket proving installation of the present invention is made up of " protruding " shape upper flange, " recessed " shape lower flange, test pad, " Ω " shape annular seal ring, outer pressure pad, interior pressure pad, outer press ring, inner pressure ring, dormant bolt, medium escape pipe, temperature sensor and micro-pressure sensor." Ω " grommet type seals and test pad and upper flange, lower flange and medium escape pipe are formed the airtight cavity that leaks hunting; Test(ing) medium causes the change of gaseous state in the cavity through the pad annular cavity that leaks hunting that bleeds, and adopts micro-pressure sensor and temperature sensor measurement gaseous state, comprises the subtle change of pressure, temperature, calculates slip by The Ideal-Gas Equation; The cavity that leaks hunting belongs to low-pressure area, can effectively avoid the leakage problem that brings as leaking cavity with the higher-pressure region, makes measurement more accurate.

The ultimate principle of slip test

The process that adopts this method to carry out the slip measurement is: test pad is loaded; Treat medium temperature reach setting value and stable after; Open the medium air intake valve; Steady pressure is determined at pressure, temperature and volume-variation in the cavity that leaks hunting in the fixed time interval then, calculates slip according to the equation of gas state.

The major parameter of test comprises pressure reduction, temperature and volume.

(1) differential pressure measurement

The medium of the cavity medium of leaking hunting for being bled by the higher-pressure region through gasket seal, the cavity that leaks hunting is in low-pressure area, can think that interior media is not to external leakage.Because the pressure at elementary errors sensor two ends is equal, voltage output value is zero before leaking.After beginning to leak hunting, micro-pressure sensor one end pressure is constant, and an end pressure that links to each other with the cavity that leaks hunting becomes big, and micro-pressure sensor is promptly exported a pressure difference.

(2) temperature survey

Upper flange, lower flange temperature adopt nichrome alumino-nickel couple to measure, and the temperature of gas all adopts nickel chromium triangle-Kao copper thermocouple measurement in the pipeline.Consider thermal resistance, avoid thermal loss, all thermocouple wires all coat with spun glass, porcelain ring.The thermocouple wire end draws receives the potential-free switch, treats to use the digital voltmeter record data again after operating mode is stablized.Bring the temperature variation on the pipeline because gas medium temperature raises, to be divided into three sections according to the distribution situation of the temperature cavity that will leak hunting.The first section cavity that to be the pad outside form with flange up and down: T _A1=T ₁₀Second section is flange and pipeline joint to flexible pipe left end: T _A2=(T ₁₀+ T ₂₀)/2; The 3rd section is flexible pipe left end to micro-pressure sensor left end: T _A3=(T ₂₀+ T ₃₀)/2.

A kind of leakage rate of high-temperature sealing gasket method of testing may further comprise the steps:

Test pad is carried between upper flange and the lower flange, and the medium escape pipe on " Ω " shape annular seal ring, test pad and upper flange, lower flange and the lower flange of sealing upper flange and lower flange is formed the airtight cavity that leaks hunting;

Open valve, in said leakage cavity, inject predetermined temperature and pressure gas medium, and keep pressure medium to stablize;

Be determined at pressure differential, temperature and volume in the fixed time interval internal leakage cavity, calculate slip according to the equation of gas state;

Pressure differential in the said fixed time interval internal leakage cavity is the pressure differential at the micro-pressure sensor two ends of connection medium escape pipe;

Temperature in the said fixed time interval internal leakage cavity comprises the temperature of leaking three different cavity segment in the cavity through temperature sensor measurement, is respectively:

Temperature T in first section cavity that the test pad outside and upper flange and lower flange form _A1, T _A1=T ₁₀

Temperature T in second section cavity of lower flange and pipeline joint to metal hose left end _A2, T _A2=(T ₁₀+ T ₂₀)/2;

The 3rd section is the temperature T in the 3rd section cavity of metal hose left end to micro-pressure sensor left side measuring junction _A3, T _A3=(T ₂₀+ T ₃₀)/2;

T ₁₀, T ₂₀, T ₃₀Be respectively temperature, metal hose left end temperature, the micro-pressure sensor left side measuring junction temperature of flange;

The said volume that is determined in the fixed time interval internal leakage cavity may further comprise the steps:

Measure the volume V of three sections each sections of cavity of the above-mentioned cavity that leaks hunting respectively ₁, V ₂, V ₃

The original pressure of timing signal established standards container is P ₀, volume V ₀

Open valve, record equalized pressure P after waiting gas equilibrium ₁

Get according to The Ideal-Gas Equation:

P _aV _i+(P _a+P ₀)V ₀＝(P _a+P ₁)(V ₀+V _i)

Abbreviation gets:

V _i＝(P ₀-P ₁)V ₀/P ₁

In the formula: P _aBe standard atmospheric pressure, P ₀Be volumetric standard pressure, P ₁Be equalized pressure, the V after the volumetric standard and the cavity connection of leaking hunting ₀Volume, V for volumetric standard _iVolume (i=1～3) for the cavity that leaks hunting;

Said calculate to leak according to the equation of gas state may further comprise the steps:

By The Ideal-Gas Equation PV=nRT, the number of moles of gas variable quantity is in the cavity that obtains leaking hunting:

$\mathrm{\Δn}=\frac{\mathrm{\ΔP}}{R}\underset{i=1}{\overset{3}{\mathrm{\Σ}}}\frac{V_i}{T_{\mathrm{ai}}};$

Above-mentioned gas molal quantity variable quantity is converted into the volume of the cavity that leaks hunting under the status of criterion:

$\mathrm{\ΔV}=\frac{T_a}{P_a}\mathrm{R\Δn}=\frac{T_a}{P_a}\mathrm{\ΔP}\underset{i=1}{\overset{3}{\mathrm{\Σ}}}\frac{V_i}{T_{\mathrm{ai}}};$

Obtain slip, i.e. the gas volume amount of unit interval internal leakage is:

$L=\frac{\mathrm{\ΔV}}{t}=\frac{1}{t}\frac{T_a}{P_a}\mathrm{\ΔP}\underset{i=1}{\overset{3}{\mathrm{\Σ}}}\frac{V_i}{T_{\mathrm{ai}}};$

In the formula: t is the time of leaking hunting, T _aBe the temperature value under the standard state, P _aFor standard atmospheric pressure, Δ P are that pressure differential, the Δ n at micro-pressure sensor two ends is gas law constant, n for the cavity gas mole variable quantity that leaks hunting, R, n ₁, n ₂, n ₃Be respectively the cavity that leaks hunting, number of moles of gas, the L of the first section cavity of cavity that leak hunting, the second section cavity of cavity that leak hunting, the 3rd section cavity of cavity that leak hunting be the volumetric leak rate.

Said temperature sensor is a nichrome alumino-nickel couple, and thermocouple wire all coats with spun glass, porcelain ring; The thermocouple wire end draws receives the potential-free switch, treats to use the digital voltmeter record data again after operating mode is stablized.

Also comprise obtaining the slip measuring accuracy, may further comprise the steps:

Ask slip measuring system precision according to the Gaussian error estimation technique, can try to achieve absolute error dL by slip:

$\mathrm{dL}=\sqrt{{\left(\frac{\∂L}{\∂t}\mathrm{dt}\right)}^2+{\left(\frac{\∂L}{\∂\left(\mathrm{\ΔP}\right)}d\left(\mathrm{\ΔP}\right)\right)}^2+\underset{i=1}{\overset{3}{\mathrm{\Σ}}}{\left(\frac{\∂L}{\∂\left(V_i\right)}d\left(V_i\right)\right)}^2+\underset{i=1}{\overset{3}{\mathrm{\Σ}}}{\left(\frac{\∂L}{\∂\left(T_{\mathrm{ai}}\right)}d\left(T_{\mathrm{ai}}\right)\right)}^2};$

Wherein: $\frac{\∂L}{\∂t}\mathrm{Dt}=-\frac{T_a}{P_a}\frac{\mathrm{Dt}}{t^2}\mathrm{\Δ\; P}\underset{i=1}{\overset{3}{\mathrm{\Σ}}}\frac{V_i}{T_{\mathrm{Ai}}};$ $\frac{\∂L}{\∂\mathrm{\Δ\; P}}d\left(\mathrm{\Δ\; P}\right)=-\frac{T_a}{P_a}\frac{d\left(\mathrm{\Δ\; P}\right)}{t}\underset{i=1}{\overset{3}{\mathrm{\Σ}}}\frac{V_i}{T_{\mathrm{Ai}}};$

$\frac{\∂L}{\∂\left(V_1\right)}d\left(V_1\right)=\frac{T_a}{P_a}\frac{\mathrm{\ΔP}}{t}\frac{1}{T_{a1}}d\left(V_1\right);$ $\frac{\∂L}{\∂\left(V_2\right)}d\left(V_2\right)=\frac{T_a}{P_a}\frac{\mathrm{\ΔP}}{t}\frac{1}{T_{a2}}d\left(V_2\right);$

$\frac{\∂L}{\∂\left(V_3\right)}d\left(V_3\right)=\frac{T_a}{P_a}\frac{\mathrm{\ΔP}}{t}\frac{1}{T_{a3}}d\left(V_3\right);$ $\frac{\∂L}{\∂\left(T_{a1}\right)}d\left(T_{a1}\right)=\frac{T_a}{P_a}\frac{\mathrm{\ΔP}}{t}\left(\frac{-V_1}{{T_{a1}}^2}\right)d\left(T_{a1}\right);$

$\frac{\∂L}{\∂\left(T_{a2}\right)}d\left(T_{a2}\right)=\frac{T_a}{P_a}\frac{\mathrm{\ΔP}}{t}\left(\frac{-V_2}{{T_{a2}}^2}\right)d\left(T_{a2}\right);$ $\frac{\∂L}{\∂\left(T_{a3}\right)}d\left(T_{a3}\right)=\frac{T_a}{P_a}\frac{\mathrm{\ΔP}}{t}\left(\frac{-V_3}{{T_{a3}}^2}\right)d\left(T_{a3}\right);$

Wherein: dt is that measuring error, the d (Δ P) of time t is the measuring error of micro-pressure sensor, d (V _i) be measuring error (i=1～3), the d (T of each section volume _Ai) be the measuring error (i=1～3) of each section temperature.

A kind of leakage rate of high-temperature sealing gasket proving installation; It is characterized in that it is made up of " protruding " shape upper flange, " recessed " shape lower flange, test pad, " Ω " shape annular seal ring, outer pressure pad, interior pressure pad, outer press ring, inner pressure ring, medium escape pipe, temperature sensor and micro-pressure sensor; Said upper flange places in the concave station of lower flange; Test pad loads between upper flange and the lower flange; Pressure pad and inner pressure ring in upper flange is provided with, lower flange is provided with outer press ring and outer pressure pad, and the outer press ring inner pressure ring is fixed through dormant bolt; " Ω " shape annular seal ring places the axial clearance place between upper flange and the lower flange, " Ω " shape annular seal ring, test pad, upper flange and lower flange and be arranged on medium escape pipe on the lower flange and form the airtight cavity that leaks hunting; Be respectively equipped with temperature sensor on upper flange and the lower flange, a measuring junction of micro-pressure sensor is communicated with the medium escape pipe.

Another measuring junction of said micro-pressure sensor is communicated with the medium setter, and the medium escape pipe is communicated with and connects metal hose, a terminal measuring junction and the valve that is communicated with micro-pressure sensor of metal hose.

The sensitivity of the volume size of the measuring accuracy of this method and the cavity that leaks hunting, the length of Measuring Time and micro-pressure sensor and temperature element is relevant.Reduce the to leak hunting volume of cavity prolongs Measuring Time and also adopts high micro-pressure sensor of resolution and thermopair, helps to improve the sensitivity of measurement.

The invention has the beneficial effects as follows:

High-temperature gasket slip method of testing that leakage rate of high-temperature sealing gasket method of testing and proving installation thereof are perfect; Rational in infrastructure; The high precision of measurement of cavity pressure has guaranteed to leak hunting; Overcome owing to leaking hunting the poorly sealed big problem of test error of bringing of cavity, therefore the slip test of high-temperature gasket is easier to realize.Structure to the cavity that leaks hunting is improved, and has set up with the high-temperature gasket slip method of testing of low-pressure area as the cavity that leaks hunting.This is to researching high-temperature gasket seal performance, and positive role has been played in the progress that promotes Sealing Technology.Satisfied the requirement of the develop rapidly of modern industry well to gasket seal.

Description of drawings:

Fig. 1 is a leakage rate of high-temperature sealing gasket proving installation structural representation of the present invention.

Fig. 2 is the point for measuring temperature synoptic diagram of leakage rate of high-temperature sealing gasket proving installation of the present invention.

Fig. 3 is the cavity volume V that leaks hunting of the present invention _iDemarcate synoptic diagram

Wherein, 1 is valve for valve, 16 for metal hose, 15 for micro-pressure sensor, 14 for temperature sensor, 13 for medium escape pipe, 12 for dormant bolt, 11 for interior pressure pad, 10 for inner pressure ring, 9 for upper flange, 8 for lower flange, 7 for test pad, 6 for the cavity that leaks hunting, 5 for " Ω " grommet type seals, 4 for outer pressure pad, 3 for outer press ring, 2.

Embodiment

A kind of leakage rate of high-temperature sealing gasket method of testing may further comprise the steps:

Test pad 5 is carried between upper flange 7 and the lower flange 6, and the medium escape pipe 11 on " Ω " shape annular seal ring 3, test pad 5 and upper flange 7, lower flange 6 and the lower flange 6 of sealing upper flange 7 and lower flange 6 is formed the airtight cavity 4 that leaks hunting;

Open valve 15, in said leakage cavity 4, inject predetermined temperature and pressure gas medium, and keep pressure medium to stablize;

Be determined at pressure differential, temperature and volume in the fixed time interval internal leakage cavity 4, calculate slip according to the equation of gas state;

Pressure differential in the fixed time interval internal leakage cavity 4 is the pressure differential at micro-pressure sensor 14 two ends of connection medium escape pipe 11;

Temperature in the said fixed time interval internal leakage cavity 4 comprises through temperature sensor 12 measures the temperature of leaking cavitys 4 interior three different cavity segment, is respectively:

Temperature T in first section cavity of test pad 5 outsides and upper flange 7 and lower flange 6 formation _A1, T _A1=T ₁₀

Temperature T in second section cavity of lower flange 6 and pipeline joint to metal hose 14 left ends _A2, T _A2=(T ₁₀+ T ₂₀)/2;

The 3rd section is the temperature T in the 3rd section cavity of metal hose 14 left ends to micro-pressure sensor 13 left measuring junctions _A3, T _A3=(T ₂₀+ T ₃₀)/2;

T ₁₀, T ₂₀, T ₃₀Be respectively temperature, metal hose 14 left end temperature, the micro-pressure sensor 13 left measuring junction temperature of flange;

The said volume that is determined in the fixed time interval internal leakage cavity 4 may further comprise the steps:

Measure the volume V of three sections each sections of cavity of the above-mentioned cavity 4 that leaks hunting respectively ₁, V ₂, V ₃

The original pressure of timing signal established standards container is P ₀, volume V ₀

Open valve 16, record equalized pressure P after waiting gas equilibrium ₁

Get according to The Ideal-Gas Equation:

P _aV _i+(P _a+P ₀)V ₀＝(P _a+P ₁)(V ₀+V _i)

Abbreviation gets:

V _i＝(P ₀-P ₁)V ₀/P ₁

In the formula: P _aBe standard atmospheric pressure, P ₀Be volumetric standard pressure, P ₁Be equalized pressure, the V after the volumetric standard and the cavity connection of leaking hunting ₀Volume, V for volumetric standard _iVolume (i=1～3) for the cavity that leaks hunting;

Said calculate to leak according to the equation of gas state may further comprise the steps:

By The Ideal-Gas Equation PV=nRT, the number of moles of gas variable quantity is in the cavity 4 that obtains leaking hunting:

$\mathrm{\Δn}=\frac{\mathrm{\ΔP}}{R}\underset{i=1}{\overset{3}{\mathrm{\Σ}}}\frac{V_i}{T_{\mathrm{ai}}};$

Above-mentioned gas molal quantity variable quantity is converted into the volume of the cavity 4 that leaks hunting under the status of criterion:

$\mathrm{\ΔV}=\frac{T_a}{P_a}\mathrm{R\Δn}=\frac{T_a}{P_a}\mathrm{\ΔP}\underset{i=1}{\overset{3}{\mathrm{\Σ}}}\frac{V_i}{T_{\mathrm{ai}}};$

Obtain slip, i.e. the gas volume amount of unit interval internal leakage is:

$L=\frac{\mathrm{\ΔV}}{t}=\frac{1}{t}\frac{T_a}{P_a}\mathrm{\ΔP}\underset{i=1}{\overset{3}{\mathrm{\Σ}}}\frac{V_i}{T_{\mathrm{ai}}};$

In the formula: t is the time of leaking hunting, T _aBe the temperature value under the standard state, P _aFor standard atmospheric pressure, Δ P are that pressure differential, the Δ n at micro-pressure sensor two ends is gas law constant, n for the cavity gas mole variable quantity that leaks hunting, R, n ₁, n ₂, n ₃Be respectively the cavity that leaks hunting, number of moles of gas, the L of the first section cavity of cavity that leak hunting, the second section cavity of cavity that leak hunting, the 3rd section cavity of cavity that leak hunting be the volumetric leak rate.

Temperature sensor 12 is a nichrome alumino-nickel couple, and thermocouple wire all coats with spun glass, porcelain ring; The thermocouple wire end draws receives the potential-free switch, treats to use the digital voltmeter record data again after operating mode is stablized.

Also comprise obtaining the slip measuring accuracy, may further comprise the steps:

Ask slip measuring system precision according to the Gaussian error estimation technique, can try to achieve absolute error dL by slip:

$\mathrm{dL}=\sqrt{{\left(\frac{\∂L}{\∂t}\mathrm{dt}\right)}^2+{\left(\frac{\∂L}{\∂\left(\mathrm{\ΔP}\right)}d\left(\mathrm{\ΔP}\right)\right)}^2+\underset{i=1}{\overset{3}{\mathrm{\Σ}}}{\left(\frac{\∂L}{\∂\left(V_i\right)}d\left(V_i\right)\right)}^2+\underset{i=1}{\overset{3}{\mathrm{\Σ}}}{\left(\frac{\∂L}{\∂\left(T_{\mathrm{ai}}\right)}d\left(T_{\mathrm{ai}}\right)\right)}^2};$

Wherein: $\frac{\∂L}{\∂t}\mathrm{Dt}=-\frac{T_a}{P_a}\frac{\mathrm{Dt}}{t^2}\mathrm{\Δ\; P}\underset{i=1}{\overset{3}{\mathrm{\Σ}}}\frac{V_i}{T_{\mathrm{Ai}}};$ $\frac{\∂L}{\∂\mathrm{\Δ\; P}}d\left(\mathrm{\Δ\; P}\right)=-\frac{T_a}{P_a}\frac{d\left(\mathrm{\Δ\; P}\right)}{t}\underset{i=1}{\overset{3}{\mathrm{\Σ}}}\frac{V_i}{T_{\mathrm{Ai}}};$

$\frac{\∂L}{\∂\left(V_1\right)}d\left(V_1\right)=\frac{T_a}{P_a}\frac{\mathrm{\ΔP}}{t}\frac{1}{T_{a1}}d\left(V_1\right);$ $\frac{\∂L}{\∂\left(V_2\right)}d\left(V_2\right)=\frac{T_a}{P_a}\frac{\mathrm{\ΔP}}{t}\frac{1}{T_{a2}}d\left(V_2\right);$

$\frac{\∂L}{\∂\left(V_3\right)}d\left(V_3\right)=\frac{T_a}{P_a}\frac{\mathrm{\ΔP}}{t}\frac{1}{T_{a3}}d\left(V_3\right);$ $\frac{\∂L}{\∂\left(T_{a1}\right)}d\left(T_{a1}\right)=\frac{T_a}{P_a}\frac{\mathrm{\ΔP}}{t}\left(\frac{-V_1}{{T_{a1}}^2}\right)d\left(T_{a1}\right);$

$\frac{\∂L}{\∂\left(T_{a2}\right)}d\left(T_{a2}\right)=\frac{T_a}{P_a}\frac{\mathrm{\ΔP}}{t}\left(\frac{-V_2}{{T_{a2}}^2}\right)d\left(T_{a2}\right);$ $\frac{\∂L}{\∂\left(T_{a3}\right)}d\left(T_{a3}\right)=\frac{T_a}{P_a}\frac{\mathrm{\ΔP}}{t}\left(\frac{-V_3}{{T_{a3}}^2}\right)d\left(T_{a3}\right);$

Wherein: dt is that measuring error, the d (Δ P) of time t is the measuring error of micro-pressure sensor, d (V _i) be measuring error (i=1～3), the d (T of each section volume _Ai) be the measuring error (i=1～3) of each section temperature.

Like Fig. 1, Fig. 2; A kind of leakage rate of high-temperature sealing gasket proving installation; It is characterized in that it is made up of " protruding " shape upper flange 7, " recessed " shape lower flange 6, test pad 5, " Ω " shape annular seal ring 3, outer pressure pad 2, interior pressure pad 9, outer press ring 1, inner pressure ring 8, medium escape pipe 11, temperature sensor 12 and micro-pressure sensor 13; Said upper flange 7 places in the concave station of lower flange 6; Test pad 5 loads between upper flange 7 and the lower flange 6; Pressure pad 9 and inner pressure ring 8 in upper flange 7 is provided with, lower flange 6 is provided with outer press ring 1 and outer pressure pad 2, and outer press ring 1 inner pressure ring 8 is fixing through dormant bolt 10; " Ω " shape annular seal ring 3 places the axial clearance place between upper flange 7 and the lower flange 6, " Ω " shape annular seal ring 3, test pad 5, upper flange 7 and lower flange 6 and be arranged on medium escape pipe 11 on the lower flange 6 and form the airtight cavity 4 that leaks hunting; Be respectively equipped with temperature sensor 12 on upper flange 7 and the lower flange 6, a measuring junction of micro-pressure sensor 13 is communicated with medium escape pipe 11.

Another measuring junction of micro-pressure sensor 13 is communicated with the medium setter, and medium escape pipe 11 is communicated with and connects metal hose 14, metal hose 14 a terminal measuring junction and the valves 15 that are communicated with micro-pressure sensor 13.

Like Fig. 3, reveal between cavity 4 and the volumetric standard and be communicated with, and be provided with valve 16.

Test pad 5 is a stainless steel soft graphite spirally wound gasket; Shim is that ring is the Q235 steel in pad; Steel band is 1Cr18Ni9Ti, and nonmetal band is a flexible graphite belt.The micro-pressure sensor model is 1151DR, and measurement range 0-0.125～1.5kPa uses object to be liquid, gas or steam, and precision is 0.5%.

In this test: t=10s, dt=0.1s, T _a=273.15K, P _a=101.33kPa, Δ P=1500Pa, R=8.315J/ (molK), V ₁=14.273cm ³, V ₂=15cm ³, V ₃=76.22cm ³, T _A1=773.15K (500 ℃), T _A2=353.15K (80 ℃), T _A3=303.15K (30 ℃), d (T _A1)=2K, d (T _A2)=0.5K, d (T _A3)=0.5K.So its maximum absolute error is:

d(ΔP)＝1.5×10 ³×0.5％＝7.5Pa

By the cubing precision is 1% can get:

dV ₁＝0.14cm ³，dV ₂＝0.15cm ³，dV ₃＝0.76cm ³

By $\frac{\mathrm{DL}}{L}=\sqrt{{\left(\frac{\mathrm{Dt}}{t}\right)}^2+{\left(\frac{\mathrm{D\Δ\; P}}{\mathrm{\Δ\; P}}\right)}^2+\frac{\underset{i=1}{\overset{3}{\mathrm{\Σ}}}{\left(\frac{d\left(V_i\right)}{T_{\mathrm{Ai}}}\right)}^2}{{\left(\underset{i=1}{\overset{3}{\mathrm{\Σ}}}\frac{V_i}{T_{\mathrm{Ai}}}\right)}^2}+\frac{\underset{i=1}{\overset{3}{\mathrm{\Σ}}}{\left(\frac{V_{i}d\left(T_{\mathrm{Ai}}\right)}{{T_{\mathrm{Ai}}}^2}\right)}^2}{{\left(\underset{i=1}{\overset{3}{\mathrm{\Σ}}}\frac{V_i}{T_{\mathrm{Ai}}}\right)}^2}}$ Can try to achieve relative error:

${\left(\frac{\mathrm{dL}}{L}\right)}^2={\left(\frac{0.1}{10}\right)}^2+{(0.5\%)}^2+\frac{{\left(\frac{0.14}{773.15}\right)}^2+{\left(\frac{0.15}{353.15}\right)}^2+{\left(\frac{0.76}{303.15}\right)}^2}{{(\frac{14.27}{773.15}+\frac{15}{353.15}+\frac{76}{303.15})}^2}$

$+\frac{{\left(\frac{14\×2}{773.15^2}\right)}^2+{\left(\frac{15\×0.5}{353.15^2}\right)}^2+{\left(\frac{76\×0.5}{303.15^2}\right)}^2}{{(\frac{14.27}{773.15}+\frac{15}{353.15}+\frac{76}{303.15})}^2}$

...∴ $\frac{\mathrm{dL}}{L}\≈1\%$

Be that the relative error that slip is measured is 1%.

By $L=\frac{\mathrm{\Δ\; V}}{t}=\frac{1}{t}\frac{T_a}{P_a}\mathrm{\Δ\; P}\underset{i=1}{\overset{3}{\mathrm{\Σ}}}\frac{V_i}{T_{\mathrm{Ai}}}$ The maximum leakage rate that the system of getting can survey:

$L_{\max }=\frac{1}{t}\frac{T_a}{P_a}\mathrm{\ΔP}\underset{i=1}{\overset{3}{\mathrm{\Σ}}}\frac{V_i}{T_{\mathrm{ai}}}$

$=\frac{1}{10}\×\frac{273.15}{101330}\×1500\×(\frac{14.273}{773}+\frac{15}{353}+\frac{76.22}{303})=1.2636/10=1.26\×{10}^{-1}({\mathrm{cm}}^3/s)$

The detectable minimum leakage rate of the systemic resolution available system that leaks hunting defines.To measurement range 0-0.125～1.5kPa, the measuring accuracy 0.5% of the system's micro-pressure sensor 13 that originally leaks hunting, so its resolution d (Δ P)=0.125 * 10 ³* 0.5%=0.6Pa, if Measuring Time is 200s, then by $L=\frac{\mathrm{\Δ\; V}}{t}=\frac{1}{t}\frac{T_a}{P_a}\mathrm{\Δ\; P}\underset{i=1}{\overset{3}{\mathrm{\Σ}}}\frac{V_i}{T_{\mathrm{Ai}}}$ Can get:

$L_{\min }=\frac{1}{t}\frac{T_a}{P_a}d\left(\mathrm{\ΔP}\right)\underset{i=1}{\overset{3}{\mathrm{\Σ}}}\frac{V_i}{T_{\mathrm{ai}}}$

$,=\frac{1}{200}\×\frac{273.15}{101330}\×0.6\×(\frac{14.273}{773}+\frac{15}{353}+\frac{76.22}{303})=0.1053/50=2.5\×{10}^6({\mathrm{cm}}^3/s)$

Be that the detectable minimum leakage rate of system is about 2.5 * 10 ^-6Cm ³/ s.

The increase or cavity 4 volumes that reduce to leak hunting can increase system leak rate measurement range.

Claims (2)

1. leakage rate of high-temperature sealing gasket method of testing is characterized in that may further comprise the steps:

Test pad (5) is carried between upper flange (7) and the lower flange (6) the leakage cavity (4) that medium escape pipe (11) composition on " Ω " shape annular seal ring (3), test pad (5) and upper flange (7), lower flange (6) and the lower flange (6) of sealing upper flange (7) and lower flange (6) is airtight; Medium escape pipe (11) is communicated with and connects metal hose (14), a terminal measuring junction and first valve (15) that is communicated with micro-pressure sensor (13) of metal hose (14); Another measuring junction of micro-pressure sensor (13) is communicated with the medium setter;

Open first valve (15), in said leakage cavity (4), inject the gas medium of predetermined temperature and pressure, and keep pressure medium stable;

Be determined at pressure differential, temperature and volume in the fixed time interval internal leakage cavity (4), calculate slip according to the equation of gas state;

Pressure differential in the said fixed time interval internal leakage cavity (4) is the pressure differential at micro-pressure sensor (13) two ends of connection medium escape pipe (11);

Temperature in the said fixed time interval internal leakage cavity (4) comprises through temperature sensor (12) measures the temperature of leaking interior three the different cavity segment of cavity (4), is respectively:

Temperature T in first section cavity that test pad (5) outside and upper flange (7) and lower flange (6) form _A1, T _A1=T ₁₀

Lower flange (6) and the interior temperature T of second section cavity of pipeline joint to metal hose (14) left end _A2, T _A2=(T ₁₀+ T ₂₀)/2;

The 3rd section is the interior temperature T of the 3rd section cavity of the left measuring junction of metal hose (14) left end to micro-pressure sensor (13) _A3, T _A3=(T ₂₀+ T ₃₀)/2;

T ₁₀, T ₂₀, T ₃₀Be respectively temperature, metal hose (14) left end temperature, the left measuring junction temperature of micro-pressure sensor (13) of flange;

The said volume that is determined in the fixed time interval internal leakage cavity (4) may further comprise the steps:

Measure the volume V of three sections each sections of cavity of above-mentioned leakage cavity (4) respectively ₁, V ₂, V ₃

The original pressure of timing signal established standards container is P ₀, volume V ₀

Open and leak second valve (16) that cavity (4) is connected, record equalized pressure P after waiting gas equilibrium ₁

Get according to The Ideal-Gas Equation:

P _aV _i+(P _a+P ₀)V ₀＝(P _a+P ₁)(V ₀+V _i)

Abbreviation gets:

V _i＝(P ₀-P ₁)V ₀/P ₁

In the formula: P _aBe standard atmospheric pressure, P ₀Be volumetric standard pressure, P ₁Be volumetric standard and the equalized pressure, the V that leak after cavity is communicated with ₀Volume, V for volumetric standard _iFor leaking the volume of cavity, i=1～3;

Saidly calculate slip according to the equation of gas state and may further comprise the steps:

By The Ideal-Gas Equation PV=nRT, obtain leaking the interior number of moles of gas variable quantity of cavity (4) and be:

$\mathrm{\Δn}=\frac{\mathrm{\ΔP}}{R}\underset{i=1}{\overset{3}{\mathrm{\Σ}}}\frac{V_i}{T_{\mathrm{ai}}};$

Above-mentioned gas molal quantity variable quantity is converted into the volume that leaks cavity (4) under the status of criterion:

$\mathrm{\ΔV}=\frac{T_a}{P_a}\mathrm{R\Δn}=\frac{T_a}{P_a}\mathrm{\ΔP}\underset{i=1}{\overset{3}{\mathrm{\Σ}}}\frac{V_i}{T_{\mathrm{ai}}};$

Obtain slip, i.e. the gas volume amount of unit interval internal leakage is:

$L=\frac{\mathrm{\ΔV}}{t}=\frac{1}{t}\frac{T_a}{P_a}\mathrm{\ΔP}\underset{i=1}{\overset{3}{\mathrm{\Σ}}}\frac{V_i}{T_{\mathrm{ai}}};$

In the formula: t is the time of leaking hunting, T _aBe the temperature value under the standard state, P _aFor standard atmospheric pressure, Δ P be the micro-pressure sensor two ends pressure differential, Δ n for leak cavity gas mole variable quantity, R is gas law constant, n, n ₁, n ₂, n ₃The number of moles of gas, the L that are respectively and leak cavity, first section cavity of leakage cavity, second section cavity of leakage cavity, leak the 3rd section cavity of cavity are the volumetric leak rate;

Also comprise obtaining the slip measuring accuracy, may further comprise the steps:

Ask slip measuring system precision according to the Gaussian error estimation technique, can try to achieve absolute error dL by slip:

$\mathrm{dL}=\sqrt{{\left(\frac{\∂L}{\∂t}\mathrm{dt}\right)}^2+{\left(\frac{\∂L}{\∂\left(\mathrm{\ΔP}\right)}d\left(\mathrm{\ΔP}\right)\right)}^2+\underset{i=1}{\overset{3}{\mathrm{\Σ}}}{\left(\frac{\∂L}{\∂\left(V_i\right)}d\left(V_i\right)\right)}^2+\underset{i=1}{\overset{3}{\mathrm{\Σ}}}{\left(\frac{\∂L}{\∂\left(T_{\mathrm{ai}}\right)}d\left(T_{\mathrm{ai}}\right)\right)}^2};$

Wherein: $\frac{\∂L}{\∂t}\mathrm{Dt}=-\frac{T_a}{P_a}\frac{\mathrm{Dt}}{t^2}\mathrm{\Δ\; P}\underset{i=1}{\overset{3}{\mathrm{\Σ}}}\frac{V_i}{T_{\mathrm{Ai}}};$ $\frac{\∂L}{\∂\left(\mathrm{\Δ\; P}\right)}d\left(\mathrm{\Δ\; P}\right)=-\frac{T_a}{P_a}\frac{d\left(\mathrm{\Δ\; P}\right)}{t}\underset{i=1}{\overset{3}{\mathrm{\Σ}}}\frac{V_i}{T_{\mathrm{Ai}}};$

$\frac{\∂L}{\∂\left(V_1\right)}d\left(V_1\right)=\frac{T_a}{P_a}\frac{\mathrm{\ΔP}}{t}\frac{1}{T_{a1}}d\left(V_1\right);$ $\frac{\∂L}{\∂\left(V_2\right)}d\left(V_2\right)=\frac{T_a}{P_a}\frac{\mathrm{\ΔP}}{t}\frac{1}{T_{a2}}d\left(V_2\right);$

$\frac{\∂L}{\∂\left(V_3\right)}d\left(V_3\right)=\frac{T_a}{P_a}\frac{\mathrm{\ΔP}}{t}\frac{1}{T_{a3}}d\left(V_3\right);$ $\frac{\∂L}{\∂\left(V_{a1}\right)}d\left(T_{a1}\right)=\frac{T_a}{P_a}\frac{\mathrm{\ΔP}}{t}\left(\frac{-V_1}{{T_{a1}}^2}\right)d\left(T_{a1}\right);$

$\frac{\∂L}{\∂\left(T_{a2}\right)}d\left(T_{a2}\right)=\frac{T_a}{P_a}\frac{\mathrm{\ΔP}}{t}\left(\frac{-V_2}{{T_{a2}}^2}\right)d\left(T_{a2}\right);$ $\frac{\∂L}{\∂\left(T_{a3}\right)}d\left(T_{a3}\right)=\frac{T_a}{P_a}\frac{\mathrm{\ΔP}}{t}\left(\frac{-V_3}{{T_{a3}}^2}\right)d\left(T_{a3}\right);$

And relative error: $\frac{\mathrm{DL}}{L}=\sqrt{{\left(\frac{\mathrm{Dt}}{t}\right)}^2+{\left(\frac{\mathrm{D\Δ\; P}}{\mathrm{\Δ\; P}}\right)}^2+\frac{\underset{i=1}{\overset{3}{\mathrm{\Σ}}}{\left(\frac{d\left(V_i\right)}{T_{\mathrm{Ai}}}\right)}^2}{{\left(\underset{i=1}{\overset{3}{\mathrm{\Σ}}}\frac{V_i}{T_{\mathrm{Ai}}}\right)}^2}+\frac{\underset{i=1}{\overset{3}{\mathrm{\Σ}}}{\left(\frac{V_{i}d\left(T_{\mathrm{Ai}}\right)}{{T_{\mathrm{Ai}}}^2}\right)}^2}{{\left(\underset{i=1}{\overset{3}{\mathrm{\Σ}}}\frac{V_i}{T_{\mathrm{Ai}}}\right)}^2}};$

Wherein: dt is that measuring error, the d (Δ P) of time t is the measuring error of micro-pressure sensor, d (V _i) be measuring error i=1～3, the d (T of each section volume _Ai) be measuring error i=1～3 of each section temperature.

2. leakage rate of high-temperature sealing gasket proving installation; It is characterized in that it is made up of " protruding " shape upper flange (7), " recessed " shape lower flange (6), test pad (5), " Ω " shape annular seal ring (3), outer pressure pad (2), interior pressure pad (9), outer press ring (1), inner pressure ring (8), medium escape pipe (11), temperature sensor (12) and micro-pressure sensor (13); Said upper flange (7) places in the concave station of lower flange (6); Test pad (5) loads between upper flange (7) and the lower flange (6); Upper flange (7) is provided with interior pressure pad (9) and inner pressure ring (8); Lower flange (6) is provided with outer press ring (1) and outer pressure pad (2); Outer press ring (1) and inner pressure ring (8) are fixing through dormant bolt (10), and " Ω " shape annular seal ring (3) places the place, axial clearance between upper flange (7) and the lower flange (6), " Ω " shape annular seal ring (3), test pad (5), upper flange (7) and lower flange (6) and be arranged on the airtight leakage cavity (4) of medium escape pipe (11) composition one on the lower flange (6); Be respectively equipped with temperature sensor (12) on upper flange (7) and the lower flange (6), a measuring junction of micro-pressure sensor (13) is communicated with medium escape pipe (11); Another measuring junction of said micro-pressure sensor (13) is communicated with the medium setter, and medium escape pipe (11) is communicated with and connects metal hose (14), a terminal measuring junction and first valve (15) that is communicated with micro-pressure sensor (13) of metal hose (14).

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