CN202432247U - Buried gas pipeline tightness test system - Google Patents

Abstract

The utility model discloses a buried gas pipeline tightness test system, which is characterized in that the temperature of the outer wall of a pipeline is measured and is converted into the gas temperature in the pipeline by adopting a formula, and moreover, the pressure in the pipeline, the temperature of the wall of the pipeline and the barometric pressure are measured every half an hour, and modified pressure drop is calculated. When the modified pressure drop is greater than 50 percent of the minimum scale division value of test pressure, tightness test is not qualified, and otherwise, the tightness test is qualified. The test system comprises an air source, a thermometer, a temperature detection transmitter, a pressure gage, a pressure detection transmitter, an intake valve, a vent valve and a computer detection platform. According to the system, the temperature of the outer wall of the pipeline is converted into the gas temperature in the pipeline, and thus, the measurement accuracy of the gas temperature in the pipeline is increased. For different test pressure, 50 percent of the minimum scale division value of the test pressure is adopted to serve as an allowable value of the modified pressure drop, and thus, the accuracy and the feasibility of a buried gas pipeline tightness test are increased.

Description

Bury ground gas pipeline leak test system

(1) technical field

The utility model relates to a kind of leak test system, particularly a kind of leak test system that is applied to bury the ground gas pipeline.

(2) background technique

Gas pipeline generally adopts buried-pipe laying, if it is improper because of leakage detection method to be embedded in underground pipeline, can cause the erroneous judgement of leak test conclusion, causes gas leakage and explosive accident.Buried pipeline is in underground about 1m depths, is difficult to detect if take place to leak.In pipeline long-time running process, the combustion gas of leak will near the soil leakage point be gathered or is spread along pipe trench, can breaking out of fire or blast when combustion gas reaches finite concentration and meets naked light.Therefore, accurately detect the buried pipeline leak-down rate, guarantee its leakproofness, safe operation is of great significance to buried pipeline.

Existing gas pipeline leak test adopts the regulation of the nation-building CJJ33-2005 of portion " engineering construction of city gas transmission & distribution and acceptance specification " to carry out; This regulation and stipulation leak test continued in 24 hours voltage stabilizing time, and it is qualified that the pressure of correction must not fall above 133Pa.

Not enough below existing gas pipeline leak test method exists:

(1) the medium temperature measuring accuracy is lower in the pipe.Thermometry at present commonly used generally is employed on the exhaust stack of valve well and installs thermometer; The temperature that records receives the influence of environment bigger; Perhaps directly thermometer is inserted in the soil of conduit upper; The temperature that records is the soil temperature around the pipeline, exists than big-difference with medium temperature in the pipe.

Calculating two states when only considering on-test and finishing falls in the pressure of (2) revising.Temperature variation can't be considered the influence of pressure in the process of the test, therefore can influence the reliability of test result.

(3) judge that whether tight pipeline is, adopt same correction pressure to fall 133Pa, lack rationality and actual operability.For different tests pressure; If adopt same correction pressure to fall 133Pa, be feasible for the situation of test pressure below 0.1MPa, if but test pressure surpasses 0.1MPa; Therefore manometric reading error will can't accurately judge the leakproofness of test pipe greater than 133Pa.

(3) summary of the invention

The utility model purpose is to overcome the existing not enough problem of ground gas pipeline leak test precision of burying, provide a kind of accurately, simple and easy to do leak test system.

Bury ground gas pipeline leak test system, comprising:

(1) pressurization of test section and pressure relief system are made up of source of the gas, suction valve, outlet valve and respective line;

(2) pressure and temperature detects and transmitting system; Weld nipple on the terminal blind plate of test section; The setting pressure table; According to the measuring accuracy needs,, be standard signal input main control computer with the pressure and temperature signal conversion of measuring through transmitter at test section outer wall mounting temperature meter at a certain distance;

(3) main control computer is made up of computer, pressure and temperature signal data interface and signaling line, and described computer comprises that the gas temperature analog module falls computing module and judge module with correction pressure in the pipe,

The gas temperature analog module is scaled gas temperature in the pipe through tube wall temperature instrumentation buret wall temperature in the described pipe, and the formula of calculating is following:

$T=\frac{{\mathrm{\λ}}_1}{{\mathrm{\δ}}_1}[(\frac{1}{\mathrm{\α}}+\frac{{\mathrm{\δ}}_0}{{\mathrm{\λ}}_0}+\frac{{\mathrm{\δ}}_1}{{\mathrm{\λ}}_1})T_{\mathrm{out}}-(\frac{1}{\mathrm{\α}}+\frac{{\mathrm{\δ}}_0}{{\mathrm{\λ}}_0})T_{\mathrm{soil}}]$

In the formula: T---gas temperature in the pipe (℃);

T _Out---the pipeline outer wall temperature (℃);

T _Soil---the test site soil temperature (℃);

δ ₀, δ ₁---pipeline and thermal insulation layer wall thickness (mm);

λ ₀, λ ₁---pipeline and thermal insulation layer thermal conductivity (w/mK)

Thermal contact resistance (mm between α---pipeline outer wall and the thermal insulation layer ²K/w);

The pipe internal pressure P that computing module will regularly detect falls in described correction pressure _i, be scaled the pressure of test original state, and calculate correction pressure and fall △ P _i

${\mathrm{\ΔP}}_i=P_0+P_{a0}-(P_i+P_{\mathrm{ai}})\frac{273+T_0}{273+T_i}$

In the formula: △ P _i---revise pressure and fall (Pa);

P ₀, P _A0---gas pressure and atmospheric pressure (Pa) in the original tube;

P _i, P _Ai---the interior gas pressure of pipe and the atmospheric pressure (Pa) that regularly detect;

T ₀, T _i---gas initial temperature and regular detected temperatures in the pipe (℃);

Described judge module is judged according to preset leak test qualification determination standard, and the output judged result: in 24 hours, if △ P falls in the correction pressure that regularly detect per half an hour _iBe not more than 50% of the minimum scale division value of pressure gauge, leak test is qualified, otherwise is defective

The utility model has the advantages that: degree of accuracy is high, simple and easy to do.

(4) description of drawings

Fig. 1 is the system architecture schematic representation of the utility model.

(5) embodiment

Do further explain below in conjunction with accompanying drawing the utility model.

Referring to Fig. 1,

Bury ground gas pipeline leak test system, comprising:

(1) pressurization of test section and pressure relief system are made up of source of the gas, suction valve, outlet valve and respective line;

(2) pressure and temperature detects and transmitting system; Weld nipple on the terminal blind plate of test section; The setting pressure table; According to the measuring accuracy needs,, be standard signal input main control computer with the pressure and temperature signal conversion of measuring through transmitter at test section outer wall mounting temperature meter at a certain distance;

(3) main control computer is made up of computer, pressure and temperature signal data interface and signaling line, and described computer comprises that the gas temperature analog module falls computing module and judge module with correction pressure in the pipe,

The gas temperature analog module is scaled gas temperature in the pipe through tube wall temperature instrumentation buret wall temperature in the described pipe, and the formula of calculating is following:

$T=\frac{{\mathrm{\λ}}_1}{{\mathrm{\δ}}_1}[(\frac{1}{\mathrm{\α}}+\frac{{\mathrm{\δ}}_0}{{\mathrm{\λ}}_0}+\frac{{\mathrm{\δ}}_1}{{\mathrm{\λ}}_1})T_{\mathrm{out}}-(\frac{1}{\mathrm{\α}}+\frac{{\mathrm{\δ}}_0}{{\mathrm{\λ}}_0})T_{\mathrm{soil}}]$

In the formula: T---gas temperature in the pipe (℃);

T _Out---the pipeline outer wall temperature (℃);

T _Soil---the test site soil temperature (℃);

δ ₀, δ ₁---pipeline and thermal insulation layer wall thickness (mm);

λ ₀, λ ₁---pipeline and thermal insulation layer thermal conductivity (w/mK)

Thermal contact resistance (mm between α---pipeline outer wall and the thermal insulation layer ²K/w);

The pipe internal pressure P that computing module will regularly detect falls in described correction pressure _i, be scaled the pressure of test original state, and calculate correction pressure and fall △ P _i

${\mathrm{\ΔP}}_i=P_0+P_{a0}-(P_i+P_{\mathrm{ai}})\frac{273+T_0}{273+T_i}$

In the formula: △ P _i---revise pressure and fall (Pa);

P ₀, P _A0---gas pressure and atmospheric pressure (Pa) in the original tube;

P _i, P _Ai---the interior gas pressure of pipe and the atmospheric pressure (Pa) that regularly detect;

T ₀, T _i---gas initial temperature and regular detected temperatures in the pipe (℃);

Described judge module is judged according to preset leak test qualification determination standard, and the output judged result: in 24 hours, if △ P falls in the correction pressure that regularly detect per half an hour _iBe not more than 50% of the minimum scale division value of pressure gauge, leak test is qualified, otherwise is defective

As stated, in conjunction with the content of accompanying drawing and embodiment, can derive the similar techniques scheme.In every case be the content that does not break away from the model utility technological scheme, any simple modification, equivalent variations and modification according to the technical spirit of the utility model is done above mode of execution all still belong in the scope of the utility model technological scheme.

Claims (1)

1. bury ground gas pipeline leak test system, comprising:

(1) pressurization of test section and pressure relief system are made up of source of the gas, suction valve, outlet valve and respective line;

(2) pressure and temperature detects and transmitting system; Weld nipple on the terminal blind plate of test section; The setting pressure table; According to the measuring accuracy needs,, be standard signal input main control computer with the pressure and temperature signal conversion of measuring through transmitter at test section outer wall mounting temperature meter at a certain distance;

(3) main control computer is made up of computer, pressure and temperature signal data interface and signaling line, and described computer comprises that the gas temperature analog module falls computing module and judge module with correction pressure in the pipe,

The gas temperature analog module is scaled gas temperature in the pipe through tube wall temperature instrumentation buret wall temperature in the described pipe, and the formula of calculating is following:

In the formula: T---gas temperature in the pipe (℃);

T _Out---the pipeline outer wall temperature (℃);

T _Soil---the test site soil temperature (℃);

δ ₀, δ ₁---pipeline and thermal insulation layer wall thickness (mm);

λ ₀, λ ₁---pipeline and thermal insulation layer thermal conductivity (w/mK)

Thermal contact resistance (mm between α---pipeline outer wall and the thermal insulation layer ²K/w);

The pipe internal pressure P that computing module will regularly detect falls in described correction pressure _i, be scaled the pressure of test original state, and calculate correction pressure and fall △ P _i

In the formula: △ P _i---revise pressure and fall (Pa);

P ₀, P _A0Gas pressure and atmospheric pressure (Pa) in the original tube;

P _i, P _Ai---the interior gas pressure of pipe and the atmospheric pressure (Pa) that regularly detect;

T ₀, T _i---gas initial temperature and regular detected temperatures in the pipe (℃);

Described judge module is judged according to preset leak test qualification determination standard, and the output judged result: in 24 hours, if △ P falls in the correction pressure that regularly detect per half an hour _iBe not more than 50% of the minimum scale division value of pressure gauge, leak test is qualified, otherwise is defective.

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