Abstract: In the traditional pipeline pressure test, whether the pipeline leaks oil will be the main technical realization of pressure test, but the performance of the pipeline itself will not be paid attention to. Based on the purpose of pipeline pressure test, this paper discusses the conditions and matters needing attention in pressure test, so as to study the existing pressure test technology in pipeline engineering.

Keywords: pipeline engineering; Pressure testing technology; Electricity leakage rate

First, the purpose of pipeline engineering pressure test

As a special way to transport special energy, pipeline engineering should fully ensure its safety in order to benefit the society. The ultimate goal of pressure test of pipeline engineering is to test the strength, rigidity and tightness of all parts in pipeline engineering, to ensure that pipeline engineering meets the national design requirements and relevant codes and standards, and to ensure the safety of pipeline engineering in use.

(1) The purpose of the strength test.

For materials, equipment and pipe fittings used in pipeline engineering, whether they have enough mechanical strength is tested to ensure the qualification of materials in pipeline engineering.

(2) The purpose of stiffness test.

For the key parts of pipeline engineering, such as parent metal, pipe fittings, valves, etc. Check the residual deformation of wood residue, and check whether these parts will deform under the corresponding pressure, so as to ensure the technical professionalism in pipeline engineering.

(3) The purpose of air tightness test.

Tightness is a qualification test for the whole pipeline project, so as to avoid the phenomenon of pipeline leakage, running and leakage after the pipeline is put into use, which will affect people's lives and cause serious harm due to the irregular overall design or some operations.

Second, the pipeline engineering pressure test should meet the conditions.

Due to the particularity of pipeline engineering itself, its pressure test should meet the following preconditions: First, the construction of pipeline engineering has been declared over, and its construction quality has been tested by relevant departments to meet the national design requirements and relevant codes and standards. Second, the design requirements have been fully met, and the supports and hangers have been installed according to strict specifications and standards. Third, welding and heat treatment shall be carried out in accordance with national standards, and the parts that do not need welding and heat treatment shall be painted to ensure air tightness. Fourthly, before the pressure test, the parts to be reinforced must be temporarily reinforced according to the pressure test requirements, and their reliability should be checked. Design should be the standard of all indicators of buried pipelines. Five, pipeline engineering in high pressure pipeline (P≥ 10MPa) before pressure testing, it is necessary to strictly review whether its quality meets the standards. Six, the pressure gauge used in the test must be calibrated to ensure that the accuracy is greater than or equal to 1.5, and the full scale should be 1.5-2 times of the measured pipeline pressure. At the same time, the dial diameter should be greater than 60mm, and at least two meters can be used. Seven, pipeline engineering pressure test should be segmented, the best segment is 1km. Eighth, before the pressure test, a pressure test plan should be made and approved by the relevant departments.

Three. Matters needing attention in pressure test of pipeline engineering

(1) Strictly control the pressure test range.

In the pressure test of pipeline engineering, instruments, equipment and keys of some systems cannot participate in the pressure test. For these parts, appropriate isolation measures should be taken or temporarily removed. At the same time, the parts with blind plates need to be clearly marked. If a valve is used to isolate the pressure control pipeline of water or steam, the temperature difference between the two sides of the valve must be kept within 65438 000 degrees Celsius. If the original pipeline is reconstructed, the pressure test pipeline and service pipeline must be separated by blind plates.

(2) Strictly control the pressure test temperature.

Due to the principle of thermal expansion and contraction, temperature will directly affect the density of liquid or gas in the pressure test pipeline, resulting in pressure test error. Therefore, for different energy sources transported in different pipelines, the temperature should also be detected during the test. It is best to carry out the water pressure test in an environment where the natural temperature is higher than 5 degrees Celsius. If it is below 5 degrees Celsius, anti-freezing measures need to be taken. The air pressure test must be based on the regulations of relevant departments, and can only be carried out after strict examination.

(3) Control the pressure test flow.

In general, due to the different topography and pipeline placement, the liquid will affect the pressure in the pipeline. Therefore, when filling water, it is necessary to ensure the stability and smoothness of the flow, and it cannot be too large. Usually, high points need to be exhausted, low points need to be filled with water, and if necessary, vacuum treatment is needed to stabilize the flow.

(4) During the pressure test, it is necessary to gradually improve and conduct the second pressure test.

The purpose of pipeline pressure test is to find problems. If problems are found during the test, they should be corrected in time. After the correction, the pipeline should be tested again, and the pipeline should be improved through repeated pressure testing to ensure its qualification.

(5) Pay attention to the removal of temporary equipment after the completion of the pressure test.

During the pressure test of pipeline engineering, some necessary temporary measures will be taken to protect the pipeline. After the completion of the pressure test, attention should be paid to the removal of temporary equipment. In addition, in the pressure test, the medium used should also be excluded after the pressure test is completed to ensure the internal energy quality of the pipeline after it is put into use.

(6) Make data records during pressure test.

There are two main aspects in the pressure test record of pipeline engineering. First, the qualified pressure test plan formulated before pressure test; Secondly, the operation records during the pressure test need to ensure the comprehensiveness and integrity of these records. If necessary, write down sketches to enhance the authenticity of the records. The data in the record should be accurate and true, and the formula should be annotated; Third, all the parameters required by the pressure test record must be filled in by the legal unit.

Four. Concluding remarks

Pipeline engineering is more and more widely used in actual transportation, and the safety requirements for its use are gradually improved. In this paper, through the general discussion of pipeline engineering pressure test, it is expected that installation technicians can realize the importance of pipeline engineering pressure test and make it more comprehensive and reasonable. For the pressure test operation of pipeline engineering, it should be more practical and take the actual demand as the first factor. In the process of pressure test, we should pay more attention to some matters, pay attention to the national standards used in pressure test, correctly understand and apply them, effectively improve the quality and efficiency of pressure test personnel, and avoid unnecessary economic losses and safety accidents.

References:

[1] An Yu. Study on pressure test optimization technology of long-distance pipeline with large drop in mountainous area [D]. Youshi University, China, 2009.

Pan-Xia Kun. Research on pressure testing technology of pipeline engineering [J]. Value Engineering, 20 15, 17: 23 1-232.

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