What vapor pressure is needed to clear this pipeline?
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What steam pressure is required to clear this pipeline? There is a 1000-meter-long DN80 pipeline, and cleaning is being carried out from the lower end toward the higher end; the flanges at the higher end have been removed, and the pipeline is filled with water. There are no vents along its length. There are 5 gantries, creating a height difference of 10 meters. At a steam pressure of 0.5 MPA, cleaning has been ongoing for 10 hours without any success. What steam pressure is needed to clear this pipeline? Are there any other ways?
If pressure relief is not possible, can we make an opening while the pressure is still present and then weld it to allow venting? We have done this before; the risk of steam causing holes is very low
Ignoring pipeline resistance: the liquid pressure at the bottom of the pipeline is p=ρgh=1000 kg/m³×9.8 N/kg×10 m=98,000 Pa=0.98 MPa. Therefore, theoretically, steam with a pressure of at least 0.98 MPa is required to achieve force balance; taking into account pipeline resistance and the effects of the gantry, it is recommended to use steam with a pressure of over 1.0 MPa.