The problem of passivation in composite plate containers
Thread Content
Our company has manufactured a deaerator, whose shell is made of stainless steel composite sheet. The customer requires pickling and passivation; in this case, should passivation be applied only to the welds or to the entire surface?
The inner surface should be pickled and passivated
Of course, it involves overall pickling and passivation; there is no such thing as treating only the weld seams.
The entire inner surface must be pickled and passivated, as the surface of the stainless steel (in areas not affected by welding) may already be damaged; without pickling, its corrosion resistance will decrease. The purpose of pickling is to remove the Cr-deficient areas on the surface of the stainless steel
The inner surface is subject to overall pickling and passivation, but this process is difficult to carry out. I used a pickling and passivation paste applied evenly over the surface, followed by rubbing, and then rinsing with water. It’s also hard to ensure that the wastewater meets the required standards, so it has to be discharged secretly in the end.
The entire stainless steel surface should be pickled and passivated
1. Why is an acid cleaning passivation paste used instead of an acid cleaning passivation solution? Isn’t it more convenient to use an acid pickling passivation solution? 2. Is there anyone in charge of ensuring that wastewater treatment meets the standards? I’m hearing about it for the first time.
The inner surface of the shell shall be treated with acid washing and passivation; the resulting passivation film shall be inspected using the blue spot method, and no blue spots indicate compliance.
If the surface of the purchased composite steel plate has been passivated, then after the equipment is manufactured, only the welds and heat-affected zones need to be passivated.