CN102392940A

CN102392940A - Method and system for testing tightness of underground gas pipeline

Info

Publication number: CN102392940A
Application number: CN2011103506721A
Authority: CN
Inventors: 潘柏定; 徐松强; 卢志明; 冯文俊
Original assignee: JIAXING GAS GROUP CO Ltd; Jiaxing special equipment test institute; Zhejiang University of Technology ZJUT
Current assignee: JIAXING GAS GROUP CO Ltd; Jiaxing special equipment test institute; Zhejiang University of Technology ZJUT
Priority date: 2011-11-08
Filing date: 2011-11-08
Publication date: 2012-03-28
Anticipated expiration: 2031-11-08
Also published as: CN102392940B

Abstract

A method and method for testing the tightness of buried gas pipelines. The method measures the temperature of the outer wall of the pipe and converts it to the gas temperature in the pipe by using a formula, and measures the pressure inside the pipe, the temperature of the pipe wall and the atmospheric pressure every half an hour, and calculates the corrected pressure. drop. When the corrected pressure drop is greater than 50% of the minimum division value of the test pressure, the tightness test is unqualified, otherwise it is qualified. The test system includes air source, thermometer, temperature detection transmitter, pressure gauge, pressure detection transmitter, intake valve, exhaust valve and computer detection platform. The method converts the temperature of the outer wall of the tube into the gas temperature in the tube, thereby improving the measurement accuracy of the gas temperature in the tube. For different test pressures, 50% of the minimum grid value of the test pressure is used as the allowable value of the corrected pressure drop, which improves the accuracy and feasibility of the tightness test of the buried gas pipeline.

Description

Tightness test method and system for buried gas pipeline

(一)技术领域 (1) Technical field

本发明涉及一种严密性试验方法和系统，特别涉及一种应用于埋地燃气管道的严密性试验方法和系统。The invention relates to a tightness test method and system, in particular to a tightness test method and system applied to buried gas pipelines.

(二)背景技术 (2) Background technology

燃气管道一般采用埋地敷设，埋在地下的管道如果因泄漏检测方法不当，会引起严密性试验结论误判，导致燃气泄漏和爆炸事故。埋地管道处于地下约1m深处，如果发生泄漏很难检测。在管道长期运行过程中，泄漏出来的燃气将在泄漏点附近的土壤积聚或沿管沟蔓延，当燃气达到一定浓度并遇明火时即会发生火灾或爆炸。因此，准确检测埋地管道泄漏率，确保其严密性，对埋地管道安全运行具有十分重要意义。Gas pipelines are generally laid underground. Improper leakage detection methods for buried pipelines will cause misjudgment of tightness test conclusions, resulting in gas leakage and explosion accidents. The buried pipeline is about 1m deep underground, and it is difficult to detect if a leak occurs. During the long-term operation of the pipeline, the leaked gas will accumulate in the soil near the leak point or spread along the pipe trench. When the gas reaches a certain concentration and encounters an open flame, a fire or explosion will occur. Therefore, it is of great significance to accurately detect the leakage rate of buried pipelines and ensure their tightness for the safe operation of buried pipelines.

现有的燃气管道严密性试验采用国家建设部CJJ33-2005《城镇燃气输配工程施工与验收规范》的规定进行，该规范规定严密性试验在持续24小时稳压时间内，修正的压力降不得超过133Pa为合格。The existing gas pipeline tightness test is carried out according to the provisions of CJJ33-2005 "Code for Construction and Acceptance of Urban Gas Transmission and Distribution Projects" of the Ministry of Construction. More than 133Pa is qualified.

现有的燃气管道严密性试验方法存在以下不足：The existing gas pipeline tightness test methods have the following deficiencies:

(1)管内介质温度测量精度较低。目前常用温度测量方法一般采用在阀门井的放散管上装设温度计，测得的温度受环境的影响较大，或者直接将温度计插入管道上部的土壤中，测得的温度是管道周围的土壤温度，与管内介质温度存在较大差异。(1) The temperature measurement accuracy of the medium in the pipe is low. At present, the commonly used temperature measurement method is generally to install a thermometer on the discharge pipe of the valve well. The measured temperature is greatly affected by the environment, or directly insert the thermometer into the soil above the pipe, and the measured temperature is the soil temperature around the pipe. There is a big difference with the temperature of the medium in the tube.

(2)修正的压力降计算只考虑试验开始和结束时两种状态。试验过程中温度变化对压力的影响无法考虑，因此会影响试验结果的可靠性。(2) The modified pressure drop calculation only considers the two states at the beginning and end of the test. The influence of temperature changes on the pressure during the test cannot be considered, thus affecting the reliability of the test results.

(3)判断管道严密与否，采用同一的修正压力降133Pa，缺乏合理性和实际可操作性。对于不同试验压力，如果采用同一修正压力降133Pa，对于试验压力在0.1MPa以下的情况是可行的，但如果试验压力超过0.1MPa，压力表的读数误差将大于133Pa，因此无法准确判断试验管道的严密性。(3) To judge whether the pipeline is tight or not, the same corrected pressure drop of 133Pa is used, which lacks rationality and practical operability. For different test pressures, if the same corrected pressure drop of 133Pa is used, it is feasible for the test pressure below 0.1MPa, but if the test pressure exceeds 0.1MPa, the reading error of the pressure gauge will be greater than 133Pa, so it is impossible to accurately judge the test pipeline. Tightness.

(三)发明内容 (3) Contents of the invention

本发明目的是克服现有埋地燃气管道严密性试验精度不足问题，提供一种准确的、简便易行的严密性试验方法和系统。The object of the present invention is to overcome the problem of insufficient accuracy of the existing buried gas pipeline tightness test, and provide an accurate, simple and easy tightness test method and system.

本发明所述的埋地燃气管道严密性试验方法，进行步骤如下：The method for testing the tightness of buried gas pipelines according to the present invention has the following steps:

(1)埋地试验管段敷设，严密性试验系统的安装，并启动计算机测试平台；(1) Laying of buried test pipe sections, installation of tightness test system, and start-up of computer test platform;

(2)在试验管段内加入压缩空气，直到管道内压力达到所需要的试验压力为止，记录初始管内压力P₀，管外壁温度T₀’和试验现场大气压力P_a0；(2) Add compressed air into the test pipe section until the internal pressure of the pipe reaches the required test pressure, record the initial pipe internal pressure P ₀ , pipe outer wall temperature T ₀ ' and test site atmospheric pressure P _a0 ;

(3)测试平台定期检测管内压力P_i，管外壁温度T_i’和试验现场大气压力P_ai；(3) The test platform regularly detects the internal pressure P _i of the tube, the temperature T _i ' of the outer wall of the tube and the atmospheric pressure P _ai of the test site;

(4)计算管内气体温度：首先通过管外壁温度计测量管壁温度，然后经过经验公式换算为管内气体温度，管内气体温度计算的公式如下：(4) Calculate the gas temperature in the tube: first measure the tube wall temperature through the tube outer wall thermometer, and then convert it to the gas temperature in the tube through an empirical formula. The formula for calculating the gas temperature in the tube is as follows:

$T T = = \frac{{λ λ}_{11}}{{δ δ}_{11}} [[((\frac{11}{α α} + + \frac{{δ δ}_{00}}{{λ λ}_{00}} + + \frac{{δ δ}_{11}}{{λ λ}_{11}})) {T T}_{out out} - - ((\frac{11}{α α} + + \frac{{δ δ}_{00}}{{λ λ}_{00}})) {T T}_{soil soil}]]$

式中：T——管内气体温度(℃)；In the formula: T - gas temperature in the tube (°C);

T_out——管道外壁温度(℃)；T _out ——pipe outer wall temperature (°C);

T_soil——试验场地土壤温度(℃)；T _soil - soil temperature of the test site (°C);

δ₀、δ₁——管道和保温层壁厚(mm)；δ ₀ , δ ₁ - wall thickness of pipe and insulation layer (mm);

λ₀、λ₁——管道和保温层导热系数(w/m·K)λ ₀ , λ ₁ —— thermal conductivity coefficient of pipe and insulation layer (w/m·K)

α——管道外壁与保温层之间的接触热阻(mm²·K/w)；α——Contact thermal resistance between the outer wall of the pipe and the insulation layer (mm ² ·K/w);

(5)将定期检测的管内压力P_i，换算为试验初始状态的压力，并计算修正压力降ΔP_i；(5) Convert the regularly detected internal pressure P _i into the pressure at the initial state of the test, and calculate the corrected pressure drop ΔP _i ;

${ΔP ΔP}_{i i} = = {P P}_{00} + + {P P}_{a a 00} - - (({P P}_{i i} + + {P P}_{ai ai})) \frac{273273 + + {T T}_{00}}{273273 + + {T T}_{i i}}$

式中：ΔP_i——修正压力降(Pa)；In the formula: ΔP _i ——corrected pressure drop (Pa);

P₀、P_a0——初始管内气体压力和大气压力(Pa)；P ₀ , P _a0 ——initial gas pressure and atmospheric pressure in the pipe (Pa);

P_i、P_ai——定期检测的管内气体压力和大气压力(Pa)；P _i , P _ai - the gas pressure and atmospheric pressure in the pipe regularly detected (Pa);

T₀、T_i——管内气体初始温度和定期检测温度(℃)；T ₀ , T _i - the initial temperature of the gas in the pipe and the temperature of regular detection (°C);

严密性试验合格判定标准：在24小时内，如果每半小时定期检测的修正压力降ΔP_i不大于压力表最小分格值的50％，严密性试验合格，否则为不合格。Judgment criteria for tightness test: within 24 hours, if the corrected pressure drop ΔP _i periodically detected every half hour is not greater than 50% of the minimum division value of the pressure gauge, the tightness test is qualified, otherwise it is unqualified.

进一步，在步骤(4)中，为了消除长距离管道内气体温度分布不均的影响，采用沿管段布置多个温度测点，以其算术平均值作为管壁温度。Further, in step (4), in order to eliminate the influence of uneven gas temperature distribution in the long-distance pipeline, multiple temperature measuring points are arranged along the pipeline section, and the arithmetic mean value thereof is used as the pipe wall temperature.

一种实现所述的埋地燃气管道严密性试验方法的系统，包括：A system for implementing the test method for the tightness of buried gas pipelines, comprising:

(1)试验管段的加压和泄压系统，由气源、进气阀、排气阀和相应管路组成；(1) The pressurization and pressure relief system of the test pipe section is composed of air source, intake valve, exhaust valve and corresponding pipelines;

(2)压力和温度检测和变送系统，在试验管段末端盲板上焊接短管，安装压力表，根据测量精度需要，在试验管段外壁每隔一定距离安装温度计，通过变送器将测量的压力和温度信号转换为标准信号输入主控计算机；(2) For the pressure and temperature detection and transmission system, short pipes are welded on the blind plate at the end of the test pipe section, and pressure gauges are installed. According to the requirements of measurement accuracy, thermometers are installed at intervals on the outer wall of the test pipe section, and the measured pressure is transmitted through the transmitter. The pressure and temperature signals are converted into standard signals and input to the main control computer;

(3)主控计算机，由计算机、压力和温度信号数据接口和信号线组成，所述的计算机包括管内气体温度模拟模块和修正压力降计算模块和判断模块，(3) main control computer, is made up of computer, pressure and temperature signal data interface and signal line, and described computer includes gas temperature simulation module in pipe and correction pressure drop calculation module and judgment module,

所述的管内气体温度模拟模块通过管外壁温度计测量管壁温度换算为管内气体温度，计算的公式如下：The gas temperature simulation module in the pipe measures the temperature of the pipe wall through the pipe outer wall thermometer and converts it into the gas temperature in the pipe. The calculation formula is as follows:

所述的修正压力降计算模块将定期检测的管内压力P_i，换算为试验初始状态的压力，并计算修正压力降ΔP_i；The corrected pressure drop calculation module converts the regularly detected internal pressure P _i into the pressure at the initial state of the test, and calculates the corrected pressure drop ΔP _i ;

所述的判断模块按照预设的严密性试验合格判定标准进行判断，并输出判断结果：在24小时内，如果每半小时定期检测的修正压力降ΔP_i不大于压力表最小分格值的50％，严密性试验合格，否则为不合格The judgment module judges according to the preset strictness test qualification standard, and outputs the judgment result: within 24 hours, if the corrected pressure drop ΔP _i periodically detected every half hour is not greater than 50% of the minimum division value of the pressure gauge %, the tightness test is qualified, otherwise it is unqualified

本发明的优点是：准确度高、简便易行。The invention has the advantages of high accuracy, simplicity and ease of operation.

(四)附图说明 (4) Description of drawings

图1是本发明的系统结构示意图。Fig. 1 is a schematic diagram of the system structure of the present invention.

(五)具体实施方式 (5) Specific implementation methods

下面结合附图本发明作进一步详细说明。The present invention will be described in further detail below in conjunction with the accompanying drawings.

参见图1，See Figure 1,

严密性试验合格判定标准：在24小时内，如果每半小时定期检测的修正压力降ΔPi不大于压力表最小分格值的50％，严密性试验合格，否则为不合格。Judgment criteria for tightness test: within 24 hours, if the corrected pressure drop ΔPi periodically detected every half hour is not greater than 50% of the minimum division value of the pressure gauge, the tightness test is qualified, otherwise it is unqualified.

(2)压力和温度检测和变送系统，在试验管段末端盲板上焊接短管，安装压力表，根据测量精度需要，在试验管段外壁每隔一定距离安装温度计，通过变送器将测量的压力和温度信号转换为标准信号输入主控计算机；(2) For the pressure and temperature detection and transmission system, short pipes are welded on the blind plate at the end of the test pipe section, and pressure gauges are installed. According to the needs of measurement accuracy, thermometers are installed at regular intervals on the outer wall of the test pipe section, and the measured pressure is transmitted through the transmitter. The pressure and temperature signals are converted into standard signals and input to the main control computer;

式中：ΔP_i—修正压力降(Pa)；In the formula: ΔP _i —corrected pressure drop (Pa);

如上所述，结合附图和具体实施方式的内容，可以衍生出类似的技术方案。但凡是未脱离发明技术方案的内容，依据本发明的技术实质对以上实施方式所作的任何简单修改、等同变化与修饰，均仍属于本发明技术方案的范围内。As mentioned above, a similar technical solution can be derived in combination with the contents of the drawings and the specific implementation manner. However, any simple modifications, equivalent changes and modifications made to the above implementation methods according to the technical essence of the present invention are still within the scope of the technical solutions of the present invention.

Claims

1. bury ground gas pipeline leak test method, it is following to carry out step:

(1) bury the ground test section and lay, the installation of leak test system, and start the computer testing platform;

(2) in test section, add pressurized air, till manifold pressure reaches needed test pressure, record original tube internal pressure P ₀, tube wall temperature T ₀' and testing ground atmospheric pressure P _A0

(3) the regular detecting tube internal pressure of test platform P _i, tube wall temperature T _i' and testing ground atmospheric pressure P _Ai

(4) gas temperature in the computer tube: at first through tube wall temperature instrumentation buret wall temperature, be scaled gas temperature in the pipe through empirical correlation then, the formula that gas temperature calculates in the pipe 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 (5) will regularly detect _i, be scaled the pressure of test original state, and calculate correction pressure and fall Δ P _i

In the formula: Δ P _i-revising pressure falls (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 (℃);

Leak test qualification determination standard: in 24 hours, if Δ 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.

2. buried pipeline combustion gas leak test method according to claim 1; It is characterized in that: in step (4); In order to eliminate the influence of gas temperature skewness in the long-distance pipe, adopt and arrange a plurality of temperature points along pipeline section, with its arithmetic mean value as tube wall temperature.

3. realize the described system of burying ground gas pipeline leak test method of claim 1 for one kind, 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; Form by computer, pressure and temperature signal data interface and signaling line; 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);

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 Δ P _i

In the formula: Δ P _i-revising pressure falls (Pa);

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

Described judge module is judged according to preset leak test qualification determination standard, and the output judged result: in 24 hours, if Δ 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.