What is the pipeline material for a 20% NaOH solution?
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What type of pipeline material should be used for a 20% NaOH solution? We used carbon steel pipelines, which lasted for about 3 years; many of the welds developed leaks. Since it was quite troublesome for the technicians to repair the pipelines each time, we wondered if there might be better alternatives Since the problems all occurred at the welds, we also wonder whether the welding rods used during construction were not appropriate What type of material is more suitable for the pipelines? I hope everyone can offer lots of suggestions; it would be great to have some criteria for selecting such materials ； Of course, everyone’s experience can also be useful. Thank you here first! ! ! Thank you all for your active participation! ! ! This post was last edited by frankqe on 2008-1-18 11:48]
Stainless steel or FRPP pipes can be considered.
PE, or FRP: victory:
Carbon steel pipelines are used, which is related to the operating temperature. For carbon steel pipelines using ordinary NaOH solutions, stress relief treatment is required after welding. Many welds have leakage defects; could it be that post-weld treatment was not carried out? For your reference.
Ours is a DN20 pipeline made of stainless steel. When the pressure is not high and the pipeline is large, steel-lined plastic pipes are also suitable.
Grade 20 steel will suffice; at 50 degrees, the corrosion resistance of stainless steel is inferior to that of carbon steel. It’s just that the welding quality needs to be carefully controlled.
From my personal experience, stainless steel, 304 will do.
Aren’t bases non-corrosive to metals? Could it be the corrosion caused by galvanic cells that has led to the corrosion of the welds?
20# will do, but the operating temperature must not exceed 60 degrees.
#20 steel will do; our 30% NaOH pipelines, which are installed outdoors, have been in use for 20 years. Apart from localized corrosion caused by the external environment, no other problems have occurred, and the inner walls of the pipelines remain smooth with no signs of corrosion. There are also 5% of NaOH pipelines that have never experienced any failures.
Our version is 304 grade, with a concentration of 48%, and it still performs very well
25% of our NaOH is made from 304L
I completely agree with this guy’s opinion. In the SEI piping classes specification, there are three grades depending on pressure and temperature; one of these grades requires post-weld heat treatment for all piping, regardless of wall thickness, while the other two grades do not require it.