Causes and Countermeasures for Leakage of Pipeline Engineering Valves
Moped Tyre,Off Road Moped Tyres,16 Inch Moped Tyres,Custom Moped Tyres Jiangyin Estone Trading Co.,Ltd. , https://www.estonerubber.com
Key words: pipeline engineering; valve; leakage; quality defect; installation and construction; preventive measures CLC number: X701 Document code: A
Introduction The valve is the control component of the oil and gas pipeline. Its function is to change the pipeline section and the transport direction of the oil and gas medium. It has the functions of diversion, cutoff, throttling, check, diversion or overflow, and pressure relief. In the process of pipeline construction, valve leakage will cause the pipeline project to fail to be delivered on time; oil and gas leakage will occur during the commissioning or commissioning of the project, which will not only cause waste of oil and gas resources, but also cause damage to the surrounding environment of the pipeline project, or even cause A serious security incident. Therefore, it is necessary to analyze the causes of leakage of oil and gas pipeline engineering valves and take effective measures to prevent and eliminate valve leakage.
1 Analysis of the cause of leakage of the valve 1.1 One of the quality defects caused by the valve in the production process is the leakage caused by the quality defects formed by the casting valve during the casting process. It includes defects such as sand holes, sand inclusions, slag holes and pores formed in the casting body. When the surface metal and paint coating of the defect surface are corroded and impacted, the hole gradually expands and leaks. The second is the leakage caused by the quality defects formed by the forging valve during the forging process. Such as cracks, cracks, folding and other issues. These inherent defects can cause leakage under the pressure of the conveying medium.
1.2 Leakage caused by improper installation of the valve flange First, the number of buckles tightened by the tightening nut during the installation of the pipeline engineering valve is inconsistent, uneven or the selection of the gasket is wrong, so that the seal is too thin and the tightness after pressing is not enough. To the sealing effect. The medium leaks to the outside of the valve body under pressure. Second, the pipe support system sinks, the position or the support system is improperly adjusted, and the pipe flange section is not parallel or misaligned with the valve flange section. There is stress between the pipe flange and the valve flange during installation, resulting in a gasket. It cannot be completely compacted and filled, causing the transport medium to leak to the outside of the valve body. Third, when the valve flange is installed, it is not tightened to the standard specified torque value, the flange sealing surface is scratched, the radial groove or other defects, the bolt sliding wire, etc. cause the individual bolts to loosen and the flange sealing surface is partially loosened. The conveying medium leaks to the outside of the valve body under the action of pressure.
1.3 Leakage caused by packing Some pipeline engineering valves are used to prevent gas, liquid materials and other media from leaking out, and the sealing device of the valve stem is installed. When the packing is installed, the gland is tightly biased, the packing bolts are not fastened, the packing is too small, the packing selection is incorrect, and the packing installation method is not correct.
2 Measures to prevent valve leakage 2.1 Strengthening process management of oil storage facilities Strengthening the process management of refined oil storage facilities is also one of the effective measures to reduce the storage loss of refined oil products. First of all, the oil depot should strictly regulate the oil storage operation, and regularly arrange the transportation operations on the basis of regular inspection of the sealing conditions of the process equipment such as storage tanks and valves to minimize the loss of refined oil. Secondly, control the flow rate of the oil in the delivery and delivery of the refined oil. When the oil depot is closed, the valve should be opened to the maximum extent to increase the flow rate of the refined oil. When the oil is turned on, the small valve should be opened to reduce the flow rate of the refined oil. In addition, the oil depot should optimize the operating conditions and strive to not affect the normal business. The sending and receiving of finished oil is completed in one time to reduce the loss caused by multiple loading and unloading. Finally, the oil depot should actively use oil and gas recovery technologies such as adsorption, condensation, and membrane separation to recover oil and gas discharged from oil during storage, prevent air pollution caused by oil and gas volatilization, eliminate safety hazards, and improve energy utilization. Reduce economic losses and get a substantial return on benefits.
2.2 Reasonable construction of refined oil pipelines When constructing oil pipelines, it is necessary to construct according to the geographical location of the pipelines. The factors affecting the pipelines should be taken into account in the actual construction. Detailed analysis of the pipelines should be carried out during the construction process. Analysis: air tightness, endurance, air pressure, etc. For the airtight inspection side, the main part is airtight detection. The main method is to seal and inflate the product oil pipeline at a certain distance. A gas pressure detecting device is provided to detect whether the air pressure in the pipe is leaking. In the construction of the pipeline, the connection point should use a gas-tight connection; in the detection of the bearing force, a high air pressure test is required to avoid the phenomenon that the product oil pipeline bursts. During the construction, the connection point of the pipeline is sealed, and the air pressure detecting device is installed. The pressure of the product oil passing through the connection point is detected, and the phenomenon that the air pressure is low at the connection point is easy to be the product oil leakage point.
2.3 Improve the product oil leak detection system to improve the product oil leak detection system, first increase the transmission pipeline detection point in the system, the transmission line all the air pressure detection, using the air pressure to detect the leakage of the product oil. The high-frequency part of the band acoustic signal is attenuated rapidly when transmitted in the oil, and the signal detected at a long distance is actually the low-frequency part of the acoustic signal. Compared with negative pressure waves, sound waves have higher sensitivity, and when a leak occurs, the pressure sudden change point can be described. For occasions where the pressure changes slowly, the negative pressure wave can show the trend of pressure change, but the sound wave does not necessarily change significantly. Therefore, it is proposed that the acoustic-negative pressure wave intelligent composite inspection side technology can improve the ability of leakage monitoring. At the same time, using the sonar or satellite system to inspect the product oil pipeline 1 can more accurately locate the product oil leakage point.
2.4 Valve transfer logistics unit (transfer station) should implement scientific management When the valve reaches the valve transfer logistics unit (transfer station), the information carried by the valve should be checked and the quality of the valve should be checked. First check whether the outer packaging of the valve is intact and there is no obvious damage or damage. Check the accompanying information of the valve manufacturer's arrival valve, including the shipping list, valve factory certificate (valve specification model, pressure rating), spare parts list, installation and maintenance instructions, main parts quality certification documents, non-destructive testing reports, Documents such as class inspection reports and test reports. Check the number of valves, fittings and spare parts. If the valve is appearance, there should be no cracks, blisters, mechanical damage, rust, missing parts, dirt and nameplate falling off. There should be protective cover at both ends of the valve to protect the sleeve groove. Time), there should be no water, rust, dirt and damage in the valve body; the valve sleeve tube (when applicable) should be free of any deformation and mechanical damage; the valve nameplate identification should include the product number, manufacturing date, nominal pressure, nominal torque, caliber, Structure length, medium flow direction, applicable medium, applicable temperature, valve body material of main parts, valve body and side body number, name of manufacturing unit, etc.; flanges, bolts and nuts of fittings and spare parts should have no visible defects. Valves, fittings and spare parts should be complete and in good condition. After the inspection, a detailed acceptance record is made, and the problems found are promptly fed back to the relevant units.
2.5 Targeted selection of pipe material The choice of pipe material follows the principle of technical practicality, stable performance, safety first, domestic and investment-saving. According to the conveying medium, the selection of the pipe is determined. When the conveying medium is water-containing oil and purified oil, the metal material is mainly used; when the conveying medium is produced water, the non-metal material is mainly used. The selection of metal pipe first ensures that the strength, rigidity, crack resistance, crack arresting property and weldability of the pipeline are met. The pipe used for partial replacement is consistent with the original parent metal, and the pipeline in the special section such as the spanning section and the high-effect zone may be appropriate. Increase the design factor. For crude oil containing hydrogen sulfide, according to the test results, the partial pressure of hydrogen sulfide is calculated and then the pipe is selected. At the same time, in view of the corrosion severity of metal pipe exposure, the limitations of internal anti-corrosion technology and cathodic protection technology, the technical characteristics of non-metallic pipes can be used to test in the gathering system and accumulate non-metallic pipes with application prospects.
2.6 Valve supervision and construction units shall strictly carry out supervision. The valve supervision and construction unit shall prepare the supervision and construction outline and supervision implementation rules according to the specific conditions of the valves to be supervised, and shall be equipped with sufficient supervision personnel. The supervisory personnel shall perform their duties conscientiously according to the requirements, and carry out corresponding work according to the document review points, witness points and stopping points determined by the outline and the rules. On time, the supervisory unit will report to the supervisory weekly and daily newspapers. Check the packaging and appearance before shipping the valve.
In conclusion, there are many reasons for valve leakage. This requires valve manufacturers, construction companies and related departments to take various measures to prevent, avoid or avoid in the production, design, procurement, supervision, inspection and storage, installation and use. The occurrence of leakage.
References [1] Li Daquan. Analysis of Leakage and Diffusion of Product Oil Pipeline and Evaluation of Hazardous Consequences [D]. Chengdu: Southwest Petroleum Institute, 2005.
[2] Feng Zhigang. Corrosion detection and residual strength evaluation of oil pipelines [D]. Chengdu: Southwest Petroleum University, 2007.
[3]ZHAO Xiaobing. Application of non-metallic pipe in oilfield gathering and transportation system[J]. Oil and Gas Field Surface Engineering, 2010, 29(8): 55-56.