A senior who works with stainless steel equipment, please come and give some help···
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When preparing the process card for stainless steel pressure vessels, should the polishing of the outer surface be mentioned in just a few words, or is it necessary to provide a detailed description? The interior of stainless steel containers needs to be pickled and passivated; is there a sequence between pickling/passivation and polishing of the outer surface?
This post was last edited by wxd9017 on 2017-5-23 at 13:36. 1. When creating a process card for stainless steel pressure vessels, should the polishing of the outer surface be mentioned briefly, or is it necessary to provide a detailed description? Theoretically, process documents are meant to guide production and should describe the process requirements in detail. As for how detailed it should be, it’s like judging the quality of an article – it depends on what the reader feels. 2. The interior of the stainless steel container needs to be pickled and passivated. Is there a specific order between pickling and passivation and the polishing of the outer surface? Pickling and passivation of the container’s interior should be carried out before polishing the outer surface, so as to prevent the already polished outer surface from being damaged during the pickling and passivation process.
Why is polishing required for the outer surface? What's going on? Generally, polishing is required on the inside of containers.
Personally, I think the external surface polishing can be mentioned briefly, but it is necessary to specify the level of polishing and the timing at which it is carried out. Additionally, if the equipment in question involves external surface polishing, this is usually done after the cylinder and the end caps have been formed separately; once everything is assembled, the welded areas such as joint welds and supports are polished again to meet the requirements specified in the drawings. The acid washing and passivation inside the equipment are carried out after the overall pressure testing of the equipment is completed. These two steps are carried out at different times. Additionally, as far as I know, after polishing the outer surface, there should be no need for acid washing or passivation.
Overall polishing; external polishing is done for aesthetic reasons
Is pickling and passivation still necessary after internal polishing?
The outer surface is polished for aesthetic reasons; therefore, it is not pickled after polishing. Inner surface polishing is mainly aimed at achieving a low surface roughness and preventing materials from sticking to the surface. Stainless steel is used for ease of cleaning; therefore, acid treatment is not applied. If polishing is done first followed by acid treatment, the acid treatment will damage the polishing effect, while if acid treatment is done first followed by polishing, it will damage the passivation layer. Thus, it’s a contradiction.
Thank you. The devices I worked on before all went through acid washing and passivation, but recent devices require polishing, and I’m not quite sure about that
When preparing the process card for stainless steel pressure vessels, it is advisable to specify relatively detailed requirements regarding the polishing of their outer surface. It is recommended to acid wash and passivate the interior of the stainless steel container before polishing its outer surface.