Detection, location, identification and repair of underground pipe network_Other business services_Other business services_Business services_Products

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I
definition
Underground pipeline is an important infrastructure of a city and the guarantee of efficient and high-quality operation of a modern city The current situation information of underground pipelines is the basic information of urban planning, construction and management, and also the guarantee of the safe operation of underground pipelines
In order to accurately and comprehensively grasp the current situation of underground pipelines and reasonably develop and utilize underground space, Shanghai has begun the underground pipeline detection project and established a relatively perfect underground pipeline information system, which is of great significance to the development and dynamic management of the city

2、 Geophysical exploration method of underground pipeline detection technology selection
1
Frequency domain electromagnetic method
2
Electromagnetic wave method (Geological Radar)
3
Magnetic method
4
Rayleigh surface wave method
5
Very low frequency method
6
Intensification polarization method, etc
Due to great limitations in practical work, frequency domain electromagnetic method is the most economical and effective method with high detection accuracy in pipeline detection engineering, and it is the preferred method of pipeline detection technology

3、 Positioning scheme of underground gas pipeline
1
Detection purpose and task
Find out the plane position, burial depth (or elevation), direction, nature, specification, material, burial time and property right unit of the underground gas pipeline, and map the underground pipeline

2
Detection range
Shanghai urban area (especially the old urban area and the urban area under transformation)
3
Overview of topography and underground pipelines in the survey area
As Shanghai is in the period of economic construction, the city has developed rapidly and its appearance is changing with each passing day
However, this has also caused great changes to the original buildings and roads, and the buried pipelines can no longer be found on the ground according to the original pipeline data map
Moreover, the urban underground pipelines are staggered and complex, and various pipelines are dotted, which also brings great difficulties to the surveying and mapping work
Great difficulties

4、 Safety inspection of urban gas pipeline network
With the extension of pipeline operation time, pipeline accidents occur from time to time
Once the gas transmission pipeline, especially the high-pressure gas transmission pipeline, breaks, the compressed gas expands rapidly, releasing a lot of energy, causing explosion and fire, which will cause huge losses
At the same time, because the substances transported by the pipeline are harmful substances, once leakage or fracture occurs, it will cause serious harm to the surrounding environment and personnel
In order to fully understand the corrosion status of the pipeline, ensure the safe operation of the gas pipeline, extend the service life of the pipeline, and prevent the leakage, explosion and other accidents caused by the corrosion perforation of the gas pipe network, the corrosion protection coating, soil environment corrosion, pipe body and other aspects of the pipeline were tested, and the corrosion degree and safety of the pipeline were evaluated

5、 Detection method
1
Anti corrosion coating inspection
The inspection of anti-corrosion coating includes ground inspection and excavation test
The sl-2088 detector is used to detect the position, direction and depth of the pipeline, and a specific alternating current signal is transmitted to the underground pipeline through the transmitter
The leakage signal is radiated to the ground at the damage of the anti-corrosion coating, and a spherical electric potential gradient centered directly above the leakage point is formed above the leakage point
There is a certain potential difference relative to the intact pipeline section and the ground without pipeline
This signal is received through the human capacitance method, Thus, the location of the damage point is determined, and the size of the damage point is determined by comparing the leakage potential
After determining the location of the damage point of the anti-corrosion coating, excavate for verification, and observe the aging degree and adhesive force of the anti-corrosion coating; The electric resistance voltage of the anticorrosive coating was measured by electric spark instrument
Measure the thickness of the anti-corrosion coating at the upper, side and lower parts of the pit, and measure 3 points at each part
Use sl— Ay508 frequency conversion and frequency selection insulation resistance tester tests the insulation surface resistance of the external anti-corrosion coating of the pipeline

2
Measurement of soil parameters
In order to understand the corrosivity of the soil environment in this section, five test pits were excavated, and the soil resistivity, pH value, water content, salt content, redox potential, DC stray current and other parameters related to pipeline corrosion were measured for each test pit to evaluate the corrosivity of the soil

3
Measurement of pipe corrosion
After excavating the deep pit, remove the anti-corrosion coating of the pipe body, observe the corrosion morphology and distribution of corrosion products, judge the corrosion components, measure the area and depth of the corrosion pit, and detect the remaining wall thickness of the pipeline
Each pit detects three groups of data, and each group measures the remaining wall thickness of the pipeline at the top and bottom of the pipe; Evaluate the residual strength of the pipeline

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