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86 512-8166609692，process specification for pickling and passivation of stainless steel in storage tank - doer equipment
classification：forum publishtime：2019-09-30 14:21:55
process specification for pickling and passivation of stainless steel in storage tank
as for the stainless steel containers of storage tanks, this specification specifies the requirements, methods and precautions for the cleaning, pickling and passivation of oil and rust stains on the surface of stainless steel containers (including parts). this procedure is applicable to pickling and passivation of chromium and nickel austenitic stainless steel vessels manufactured by our company.
pickling and passivation process flow:
degrease and clean dirt - clean water flushing passivation clean water flushing - blow dry
preparation before pickling and passivation:
1 personnel and protection
operators shall receive safety operation training before taking up their posts and be able to handle emergencies correctly.
wear neat clothes before operation, and wear rubber gloves, rubber shoes, masks, hats and protective eye masks.
2 workpiece
pickling and passivation pretreatment can be carried out for stainless steel containers or parts after manufacturing according to the requirements of drawings and process documents and after the specified items are inspected as qualified.
clean the welding slag and spatter on the weld and its two sides, and remove the oil stain and other dirt on the surface of the machined parts of the container with gasoline or cleaning agent.
when removing foreign matters on both sides of the weld, remove them with stainless steel wire brush, stainless steel shovel or grinding wheel. after removal, wash them with clean water (the chloride ion content in the water does not exceed 25mg / l).
when the oil stain is serious, remove the oil stain with 3-5% alkali solution and rinse it with purified water.
the oxide scale of stainless steel hot working parts can be removed by mechanical sand blasting. the sand must be pure silicon or alumina.
formulation of pickling and passivation solution and paste
pickling solution formula: nitric acid (specific gravity 1.42) 20%, hydrofluoric acid 5%, and the rest is water. the above is volume percentage.
pickling paste formula: 20ml hydrochloric acid (specific gravity 1.19), 100ml water, 30ml nitric acid (specific gravity 1.42), 150g bentonite.
passivation solution formula: nitric acid (specific gravity 1.42) 5%, potassium dichromate 4g, and the rest is water. the passivation temperature is room temperature.
passivation paste formula: 30ml nitric acid (concentration 67%), 4g potassium dichromate, add bentonite (100-200 mesh) and stir until paste.
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