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When natural gas is extracted from strata, it contains many solid and liquid impurities. Some of these impurities are removed using devices such as separators and filters, but impurities still remain in the natural gas. Some of the natural gas produced from the strata contains the acidic gas CO2, which can cause corrosion to the pipe walls under the high pressures at the gas gathering stations. When factors such as corrosion, erosion, and dirt accumulation cause the wall roughness of the pipe to exceed the allowable range specified by the measurement standards, it affects the accuracy of the measurement system. The roughness of the inner wall of the pipeline is related to the impurity content in natural gas, the percentage of corrosive components, the gas flow rate, the pressure and temperature inside the pipeline, as well as its service life. https://mp.toutiao.com/mp/agw/article_material/open_image/get?code=YTU2NzhlMjQyMmFkMzU4ZDhmMzUxMzc4ZmJjNDc5MGUsMTYxNTg2MjA5OTEyNg== The conditions under which a orifice flow meter can operate properly include, but are not limited to: 1. The length of the straight sections upstream and downstream of the orifice plate must meet the requirements of the measurement standards ； 2. The roundness and diameter of the measuring pipeline and straight sections meet the requirements of the metrological standards ； 3. The inner wall roughness of the measurement pipeline and straight sections meets the requirements of the metrological standards. In the above three cases, the roughness of the straight pipe section is most prone to change, as its roughness gradually increases due to pressure corrosion and acid corrosion of the natural gas. To ensure that wall roughness does not affect the accurate measurement of orifice flow meters, the roughness of the straight pipe upstream of the throttling orifice and the inner walls of the measuring tube must comply with the standard GB/t21446-2008 \"Orifice Flow Meters for Measuring Natural Gas Flow Rates\". The flow of some natural gas causes severe erosion and corrosion on the inner wall of the measuring tube. Changes in the wall roughness lead to variations in the actual discharge coefficient, and the uncertainty in flow measurement will exceed the original value. Replacing the measuring tube that has been in use for a long time and shows significant changes in wall roughness is the safest way to reduce measurement errors and ensure measurement accuracy.