Problems with pipeline air purging?
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Our factory needs to purge a 1.8 km long pipeline belonging to the head office. At one end of this pipeline is an air compressor (with a designed capacity of 5300 m3/h and a designed pressure of 2.0 MPa). A temporary DN80 pipe connects the air compressor to the pipeline to be purged; the diameter of this pipe is DN150 at the beginning, and it becomes DN200 from 100 meters onward up to a total length of 1.8 km. There are several branch pipes of DN150 at the beginning of the pipeline to be purged. What is the best method for performing this purging process? How should the required flow rate and pressure level be calculated? :loveliness: Last edited by cy130 on 2009-3-21 23:55 in this post ]
This pipeline needs to be thoroughly purged. Here are a few suggestions for the person in charge: 1. It is advisable to install a relatively large storage tank at the outlet of the air compressor, or use a regulating device before the air enters the pipeline to be purged, so as to ensure a sufficient air flow rate at the moment of purging； 2. Purge the pipeline in sections; it is advisable to install temporary valves at the inlet of each section for control ； 3. Each branch pipe should be purged separately, and the valves should be closed or blocked after purging; otherwise, it is difficult to ensure effective purging at the ends of the piping system.
1. Water is used as the medium for the pressure test, with the test pressure being 1.5 times the design pressure. If the design drawings specify that the test pressure is higher than 1.5 times the design pressure, the pressure test shall be carried out in accordance with the requirements of the design drawings. 2. The valves on the pipeline under test should be in the open position (or the valve cores should be removed). 3. During the test, pressure should be increased gradually. When the pressure reaches 50% of the test pressure, if no abnormalities or leaks are detected, the pressure should be increased further at a rate of 20% of the test pressure. The pressure should be held at each level for 3 minutes until it reaches the test pressure, after which it should be held for another 10 minutes. Then the pressure should be reduced to the design pressure. The duration of holding the pressure at this level depends on the requirements of the leak detection process; the test is considered successful if no leaks are detected using a foaming agent
And it’s best to perform pressure testing first, then pipe blowing. If you have high requirements for the quality of the compressed air produced, it is recommended to remove the core of the pipeline filter before cleaning the pipes; otherwise, the costs associated with such cleaning will be very high. Additionally, if high cleanliness standards are required for the pipes, it is recommended to perform purging at the pipe outlet under a pressure of around 2–3 bar for 2–3 days. This helps to dislodge the particles and slag adhering to the inner walls of the pipes due to the action of strong airflow. After that, the pipe filter element should be installed, and purging should be continued for another 2 days at a pressure slightly lower than that used in actual production, thereby reducing the amount of residue remaining in the pipes. Of course, the power consumption is also a bit high. Many of our companies that produce precision products such as LCDs and semiconductors use compressed air systems in this manner. :lol
It is very necessary to install a buffer tank at the compressor outlet; if not, blast cleaning can be used