Consultation on hot work on pipelines with materials carried
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Dear colleagues: There is an aniline transfer arm in the company that has developed a sand hole, and welding repairs are required. The oil transfer arm has been purged and washed with water. However, if aniline compounds are not cleaned with a specific solvent, some residue remains on the inner wall. Can work be carried out after nitrogen purging reduces the gas concentration to below 4% LEL? There is also a dichloroethane pipeline that wasn’t equipped with static grounding initially; grounding wires need to be welded in place. Nitrogen displacement can be used, but it isn’t possible to completely remove the remaining dichloroethane inside the pipeline. Is there any way to perform welding work outside the pipeline? Experts with practical experience, please share your insights
If welding is to be carried out, proper safety measures must be in place; the pipelines need to be isolated from the system, and blind flanges should be used； Ideally, if the test results are satisfactory and the level is slightly above the standard, it’s okay to use a slight flow of nitrogen for purging; however, this isn’t entirely reliable. It’s best to follow the firework safety regulations strictly, implementing each requirement one by one, so as to work with peace of mind
For such pipelines, it is best to engage a company specialized in plugging leaks under pressure; use non-flame-based plugs for temporary sealing, and carry out thorough repairs during major maintenance