What are the requirements regarding pipeline length and elbows during the burst cleaning of gas pipelines?
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This post was last edited by cjm6536536 on 2018-7-6 at 10:29. For purge gas pipelines with diameters ranging from 6\" (inclusive) to 24\" (exclusive), explosive purging is required. In practice, some pipelines are over 50 meters long from the gate valve at one end to the nearest flange connection at the other end, and there are many bends along the way; it’s uncertain whether such pipelines can be purged using this method. I hope those familiar with this field can provide guidance – are there any standards or regulations that specify requirements for explosive purging? Or what are the experiences when using blast purging? I checked the three standards: \"GB 50517-2010 Code for Acceptance of Construction Quality of Petrochemical Metal Piping Projects\", \"GB 50184-2011 Code for Acceptance of Construction Quality of Industrial Metal Piping Projects\", and \"GB 50235-2010 Code for Construction of Industrial Metal Piping Projects\" – none of them specify any requirements regarding the length of pipelines to be purged with air
I’m not very familiar with these standards and regulations, so I can only carry out blasting based on the actual conditions on site; as long as the goal is achieved that’s enough. If the pipelines are long or the elbows are large, it just means more blasts will be necessary
Generally, the high-pressure sections are purged using air through blasting. During this purging process, once it is visually confirmed that no smoke or dust is emitted, a wooden target covered with white cloth or painted white should be placed at the exhaust outlet for inspection; it is considered satisfactory if no rust, dust, moisture, or other debris is present on the target within 5 minutes. Several videos on purging: http://v.youku.com/v_show/id_XNDU0NjY4NTUy.html Steam purging: http://v.youku.com/v_show/id_XMjk3ODE1OTA0.html Sand blasting for cleaning. A burst disc is installed at the lowest point of the system; it ruptures when the system pressure reaches the specified level, thereby removing impurities such as rust and weld slag from within the pipes.
Thank you for your reply. When using blast discs, people mark them with a cross or a plus sign using a knife; how do you determine the depth of these marks? Sometimes, when the incision is made too deep, the pressure relief disc does not rupture even when the specified pressure is reached; other times, when the incision is too shallow, it ruptures before the intended pressure is achieved, which is a great waste of time.
This post was last edited by sdwfsgyykai on 2018-7-12 09:17. Just perform a few more purges; if you’re worried, you can use PIG to clean the pipelines...
For ordinary blasting, it is not necessary to set the system pressure to the design pressure; a few kilograms of pressure is usually sufficient to achieve the purpose of cleaning the pipes. Therefore, gaskets used for this purpose are typically thin asbestos sheets, which will burst open under a pressure of around 4–5 kilograms
This post was last edited by cjm6536536 on 2018-7-15 at 19:47. Many purge scheme settings are set at around 0.3 MPa. Also, keep in mind that asbestos is a material that can cause diseases such as cancer and asbestosis; Sinopec banned its use back in 2016.