It is normal for the "rust" phenomenon to appear on the surface of the stainless steel welded pipe. Let's take a look.
"Although the welded pipe does not rust in theory, once it rusts, it is not a welded pipe, and there may be a problem with the steel." Such views lack or one-sided understanding of butt welded pipes. In fact, welded pipes will rust under certain conditions. Theoretically, the welded pipe has the ability to resist atmospheric oxidation—that is, rust resistance, and also has the ability to resist corrosion in the medium containing acid, alkali and salt—that is, corrosion resistance. However, the size of its anti-corrosion ability varies with the chemical composition of its steel itself, the state of mutual addition, the conditions of use and the type of environmental media. For example, 304 steel pipe has absolutely excellent anti-corrosion ability in a dry and clean atmosphere, but if it is moved to the seaside area, it will rust for a long time in the sea fog containing a lot of salt; while the 316 steel pipe shows good. Therefore, it is not any kind of welded pipe that can resist corrosion and rust in any environment. The rusting of stainless steel welded pipes is mainly reflected in the appearance of brown rust spots (spots) on the surface.
Prevansyon rouye nan tiyo soude se sitou ki baze sou yon trè mens, fèm ak ki estab chromium -fim oksid rich (fim pwoteksyon) ki te fòme sou sifas li yo, ki anpeche enfiltrasyon an kontinyèl ak oksidasyon nan atòm oksijèn, epi li jwenn kapasite nan. reziste rouye. Yon fwa gen kèk rezon tankou transpò, kolizyon, ak kontak ak lòt atik, fim sa a se kontinyèlman domaje, ak atòm oksijèn nan lè a oswa likid yo ap kontinye enfiltre oswa atòm fè nan metal la ap kontinye separe soti, fòme fè ki lach. oksid. Sifas metal yo tou sijè a korozyon konstan. Gen anpil fòm domaj nan fim sifas sa a. Anplis de rezon ki anwo yo nan itilizasyon chak jou, gen bagay sa yo:
1. Sou sifas tiyo a soude, gen depo pousyè oswa patikil metal eterojèn ki gen lòt eleman metal. Nan lè imid la, dlo kondanse ant adezyon an ak tiyo soude a konekte de a nan yon mikwo-batri, ki deklanche yon reyaksyon elektwochimik. , se fim nan pwoteksyon domaje, yo rele korozyon elektwochimik.
2. Sifas tiyo a soude konfòme yo ak ji òganik (tankou legim, soup nouy, krache, elatriye), ki konstitye asid òganik nan prezans dlo ak oksijèn, ak asid òganik pral korode sifas metal la pou yon tan long. .
3. Sifas tiyo a soude konfòme yo ak sibstans ki gen asid, alkali ak sèl (tankou dlo alkali ak dlo lacho pwojeksyon soti nan mi yo dekorasyon), sa ki lakòz korozyon lokal yo.
4. Nan lè polye (tankou atmosfè a ki gen yon gwo kantite ilfid, oksid kabòn, oksid nitwojèn), lè w rankontre dlo kondanse, li pral fòme tach likid nan asid silfirik, asid nitrique ak asid acetic, sa ki lakòz korozyon chimik.
The above conditions can cause damage to the protective film on the surface of the welded pipe and cause rust, resulting in other "rusting" phenomena such as color rust, spots (spots) on the surface of the steel pipe