Petroleum Pipeline Pressure Transducer Online Calibration

This article describes the online calibration method for pressure transducers used in oil gas pipelines.The pressure transducer are important monitoring and control instruments for oil pipelines. It plays a vital safety protection role in the normal operation of the entire pipeline. The pressure transducer can monitor the pressure data collected in the field and display it synchronously to the monitoring host of the station control room. It can alarm the abnormal pressure value and feed back the abnormal situation to the station staff. At the same time, the pressure transducer can also perform the switch control of the corresponding pipeline valve through the designed control program according to the collected pressure. It will help avoid serious safety incidents. Therefore, the accuracy of the pressure value measured by the pressure transducer must be guaranteed by traceability. Otherwise, it is easy to cause false alarms and misoperations, resulting in unnecessary losses.
The pressure monitoring method for the oil gas pipeline is mainly through the bypass of the main pipeline. Generally, the root valve and the vent valve as well as the vent tube are installed on the bypass. Then connect the pressure transducer to the monitoring host to connect the two for pressure monitoring and control. The root valve, vent valve and vent tube are mainly installed to facilitate the maintenance and replacement for the pressure transducer in the future. During normal operation, the root valve is open and the vent valve is closed. The pressure of the main pipe can be smoothly passed through the bypass to the pressure transducer, and then be transmitted to the monitoring host via data. When it is needs to replace and maintain the pressure transducers, it needs to be relieved. At this point, the root valve can be closed and the pressure connection between the main pipe and the bypass can be interrupted. Then, the open the vent valve, and the residual pressure of the bypass is released through the vent pipe to complete the pressure relief work.

• Conventional calibration work for the pressure transducer

In conventional calibration work, the pressure transducer needs to be removed from the pipe first. Then connect the pressure transducer to the standard meter and pressurize it. During the disassembly process, the pressure transducer, pressure and bypass interface need to be removed. It is also necessary to remove the power supply line of the pressure transducer. The power supply line is deeply buried in the insulating cover. The disassembly of the entire pressure transducer requires 2 people to work together. The disassembly takes nearly 15 minutes. Multiple times of disassembly and installation of the interface will easily cause damage to the interface. It will result in a tight pipe seal, resulting in air leakage and accidents.
For pressure transducers, the conventional calibration method can meet the requirements of metrological traceability, but it also has many shortcomings. The efficiency of metering work is too slow. Longer time for disassembly and installation. Frequent disassembly and installation will easily cause damage to the connectors.

• Pressure transducer online calibration

To solve the above problem, we can pressurize the blow-down pipeline. This method can completely solve the problem of online calibration for pressure transducers. Specific operations are as follows.
Firstly, close the root valve to cut off the pressure between the bypass and the main line. Then open the vent valve to let the residual pressure in the bypass be exhausted. Then remove the vent tube. Connect the high-pressure hose to the bypass venting section to complete the connection between the standardizer and the pressure transducer. In this new online inspection method, we only need to dismantle the venting pipe. The parts that need to be disassembled are relatively small, just remove the venting thread, so one person can complete the disassembly work in 1min. In addition, the disassembly is a non-essential part, which does not affect the main connecting part, which is safe and efficient. While pressurizing, the root valve can be fine-tuned and use the pressurized gas in the pipe as the pressure source. It also saves the workload for the pressure transducer calibration work.
It can be seen that the pressurizing the blow-down pipeline method has high detection efficiency, strong safety reliability and operability. It is a method that can save time and energy. For pressure instruments with a structure such as root valve and vent valve on an oil gas pipeline, this method has a wide versatility.