Seeking expert help with gas pipeline pressure drop calculation
Thread Content
For the airtightness test of a gas pipeline, the pressure was maintained for 24 hours; it decreased from 5.6 KG to 5.4 KG. Is this considered acceptable? What is the calculation formula?
Test the password; it has an allowable value, and as long as it does not exceed this value, it is considered valid
The pressure drop calculation formula for gas pipelines can use empirical formulas or fluid dynamics formulas. Empirical formula: ΔP = L × K × Q^2 / d^5 (units: Pa), where ΔP is the pressure drop (Pa), L is the pipe length (m), K is the friction coefficient, Q is the flow rate (m^3/s), and d is the inner diameter of the pipe (m). Fluid dynamics formula: ΔP = f × L × ρ × V^2 / 2D (units: Pa). Here, ΔP is the pressure drop (Pa), f is the viscous drag coefficient, L is the length of the pipe (m), ρ is the density of natural gas (kg/m^3), V is the flow velocity (m/s), and D is the diameter of the pipe (m). Based on the information you provided, assuming the inner diameter of the pipe is d and the flow rate is Q, the pressure drop can be calculated using the formula above. Based on the calculation results, it is determined whether the voltage drop is within a reasonable range; if the voltage drop falls within the design requirements, the test is considered successful. .
What if it is only an airtightness test (pressure retention test), and the length of the pipe is unknown?
I just want to figure out what the allowable range value is :(
Isn’t it in your design documents?
Calculating the airtightness of a pipeline when only the pressure drop and time are known can be somewhat difficult. Because pipe length is one of the important parameters affecting pressure drop. If only the pressure drop and time are known, it is not possible to accurately calculate the airtightness of the pipeline. When conducting pipeline airtightness tests, the pipeline length is generally determined in advance, and the expected pressure drop is calculated based on design requirements and fluid dynamics formulas. Then, the pressure reduction obtained through actual testing is compared with the expected value to evaluate the airtightness of the pipeline. If the actual pressure drop during testing differs significantly from the expected value, it may be necessary to check for leaks or other issues in the pipes. In short, when conducting pipeline airtightness tests, it is best to determine the pipeline length in advance and use the appropriate formulas for calculation, so as to more accurately assess the pipeline’s airtightness. .
Then contact a design institute; this should be available there
If only the pressure drop and time are known, without information such as pipe length, it is indeed impossible to accurately determine the acceptable range. In this case, it is recommended that you refer to relevant industry standards or technical specifications; for example, the **Standard for Protection against Gas Supply and Use (GB 50028-2006)** may contain provisions regarding the evaluation requirements and acceptable ranges for airtightness tests. At the same time, it is also recommended that you consult professionals in related fields, such as engineers and experts, to obtain more specific answers and advice. They will provide more accurate judgments and guidance based on the actual situation and experience. .