Pipeline construction issues at Tie-In points
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This post was last edited by zhanong on 2011-5-12 at 15:32. It was mentioned in one of the proposals that for the construction of the TP points of the pipeline, cold cutting is required, and work can proceed only after the analysis shows that everything is satisfactory. What do you all think? I don’t think it’s necessary. Firstly, the key to construction safety is thorough displacement of the material inside the pipes; if this displacement is not complete, no cutting process can be considered safe, as sparks will definitely be generated during cutting. Secondly, the so-called cold cutting refers to the absence of heat input, not to whether sparks are produced. For example, cold cutting using stainless steel yields better joint quality compared to thermal cutting; methods such as cutting blades/plasma are preferable in this regard, but their efficiency is lower. If cold cutting here refers to the use of a saw bow, then I must say it’s not very impressive. Secondly, regardless of the type of TP point construction, sampling and analysis points do exist; sampling and analysis must be carried out again before construction, and work can only proceed once the results are satisfactory.
According to the poster’s understanding, it is a theoretical expert who has no knowledge of practical operations. Firstly, there are many bends and branch pipes in the system, as well as frequent changes in pipe diameter; therefore, no purging or cleaning method can guarantee that all residues and deposits in certain areas of the pipes are completely removed. The evaporation of these residues can produce flammable and explosive gases. Therefore, sampling is required at the Tie-in points; samples taken from other locations cannot represent the actual gas conditions at TP points that are located at greater distances. However, it is not possible to have sampling points throughout the area near the TP points (within 1M), so cold cutting must be used, that is, manual spark-free drilling (4mm) in the pipeline to obtain samples of the gas inside for analysis. This is an essential inspection method for the construction of the TP point in process pipelines.
Reply to 2# wzhengkui: From your reply, it seems you have practical experience in this area. I would like to ask: How is spark-free drilling carried out? Tools, operation methods.
Since it is a cold-cutting method, it can meet the requirements... It has been in use for a long time now; I even saw it at the site some time ago! It ensures no sparks are generated···· For reference
Reply to 3# zhanong: Have you really never seen sparkless drilling? I remember that drilling rarely produces sparks. They even use bench drills to drill high-sensitivity titanium and zirconium materials. A bit confused: dizzy:
This post was last edited and replied to by zhanong on 2011-5-14 at 17:03. Reply 5# zhangyi7528: In metal processing using turning, milling, and drilling, sparks are generally not visible, as sparks are actually pieces of metal at high temperatures. Static electricity-induced sparks between metals are uncommon and only occur under conditions of high-speed impact. The problem is that in the situations we are describing, combustion and explosion are not desired. The temperature generated by drills with high-speed chips is actually higher than the spark temperature, which is equally unsafe; that’s what I mean. So I say that if you’re worried about sparks, drilling a hole with a drill seems even more dangerous. If you don’t believe me, go upstairs and use a drill on a liquefied gas cylinder to see if it will explode. Saying I’m a theoretical worker on the second floor is too much of a compliment for me; I originally work in mechanical processing. I asked you how to drill and what tools to use, thinking you actually had practical experience in this area. If things are done exactly as you said, then it seems like you only know one side of the story and not the other. If it must be emphasized that thorough cleaning is impossible and that it’s dangerous, then the only option is to use low-speed manual drilling for sampling; I really can’t think of any better methods or tools.