K-2 Pickling Paste for Stainless Steel
K-2 Paste is used to clean weld seams and the areas surrounding the welds.
WHY TO PICKLE & PASSIVATE ON STAIN
Pickling & passivation ensures corrosion resistance for components of stainless steel ancl thus influences its life ancl use.
The corrosion resistance of stainless steel is due to the presence of atleast thirteen percent chromium in the alloy.With oxygen, the chromium forms a dense chemically resistant passive layer of chromium oxide protecting the surface of the component against corrosion. The passive layer usually forms again after abrasion. The pre-conclition to corrosion resistance and passive layer is a metallically pure surface with a high percentage of chromium.
Every mechanical treatment damages the top layer of components i.e.
• Contamination with ferritic matter
• Change in the structure of the layers
• Development of inbuilt stress
• Recluction of chromium content
Heat treatment like annealing ancl welcling leads to scaling and discolouration. This not only deteriorates the appearance of the component but also its corrosion resistance due to the presence of ferric oxides. A continuous passive layer of chromium oxide cannot form here. Hence it is a must to have a metallically clean and pure surface by pickling prior to passivation.
Corrosive stain on insufficiently passivated stainless steel leads to the following:
• Pitting corrosion,
• Crevice corrosion,
• Stress corrosion cracking,
• Intercrysta Iline corrosion ancl,
• Corrosion resulting from contact with foreign metals.
A dense passive layer con only form on metollicolly pure surfaces. Professionally pickled passivated stainless steel surfaces and welded seams:
• Are metallically pure, free of scales and discolouration
• Give the full corrosion resistance to the component
• Have a decorative metallic appearance
Paste form covers 90-100 meters of weld seams with 1 kg. of chemical.
over grinding and polishing
Grinding is a mechanical action that tends to push the surface iron into the metal thereby contaminating the metal surface. This ultimately leads to rusting & corrosion, therefore K-2 pickling & passivation is a must after every mechanical action. K-2 pickling removes all the free iron from the metal surface & passivation helps in regenerating the chromium oxide layer that protects the surface from further corrosion.
Polishing action leaves behind tiny invisible black polishing particles or compounds on the metal surface which contaminates the metal surface & the presence of such particles on the surface make way for rusting & corrosion. Therefore it is necessary to carry out K-2 passivation after every finishing & polishing action so as to have a clean, passivated, corrosion resistant metallic surface.
K-2 PICKLING & PASSIVATION
K-2 chemicals not only removes the oxide scales, rusts particles, annealing colours from stainless steel surface making it sterile & passive but also protects the surface from further corrosion. K-2 Pickling & Passivation done on any stainless steel surface after mechanical or non-mechanical action ensures smooth, metallically pure surface having full corrosion resistance which increases the life & performance of the components.
APPLICATION PROCEDURE FOR PASTE
Add 50 gms of SI. 56 Degreaser to 1 ltr. of water (5% w/v.). Apply solution on the surface for 10-15 minutes & then wash thoroughly and allow the surface to air dry.
Paste is to be applied on the weld seams and surrounding area with a brush.
Leave the Paste on the weld seams for 30-45 minutes depending on the thickness of the oxide scale.
Brush the surface with a plastic bristled brush and then wash surface thoroughly with high pressure water and allow the surface to air dry.
Next apply Passivation solution and leave it for 20-25 minutes.
Finally clean the surface thoroughly with demineralised water and dry.