Surface damage treatment and cleaning of hotel baggage car

Production is often carried out in dusty places, and there is often a lot of dust in the air, which keeps falling on the surface of equipment. They can be removed with water or alkaline solution. However, adhesive dirt requires high-pressure water or steam to clean it.

2, floating iron powder or embedded iron

Free iron will rust and corrode stainless steel on any surface. Therefore, it must be deleted. Floating powder can usually be removed with dust. Some of them have strong adhesion and must be embedded with iron. In addition to dust, there are many sources of surface iron, including cleaning with ordinary carbon steel wire brush, shot peening with sand, glass beads or other abrasives previously used on ordinary carbon steel, low alloy steel or iron castings, or grinding the above-mentioned non-stainless steel products near stainless steel parts and equipment. If the stainless steel is not protected during unloading or hoisting, the steel wire rope, spreader and iron pieces on the workbench are easy to embed or dirty the surface.

3, scratches

In order to prevent the accumulation of process lubricants or products and/or dirt, scratches and other rough surfaces (such as glass beads for dry sandblasting and abrasives) must be cleaned mechanically.

4. Thermal tempering color and other oxide layers

If stainless steel is heated to a certain high temperature in the air during welding or grinding, chromium oxide hot tempering color will appear on both sides, lower surface and bottom of the weld. The thermal tempering color is thinner than the oxidation protective film, which is obviously visible. Depending on the thickness, the color can be rainbow, blue, purple to light yellow and brown. Thicker oxides are generally black. It is caused by staying in high temperature or high altitude for a long time. When any kind of oxide layer emerges, the chromium content on the metal surface will decrease, thus reducing the corrosion resistance of these areas. In this case, not only the thermal tempering color and other oxide layers should be removed, but also the chromium-poor metal layer below them should be removed.

5. Rust spots

Stainless steel products or equipment sometimes appear rust before or during production, indicating that the surface is seriously polluted. The equipment must be derusted before being put into use, and the thoroughly cleaned surface should be inspected by iron test and/or water test.

6, rough grinding and machining

Both grinding and machining will cause surface roughness, leaving defects such as grooves, overlaps and burrs. Each defect may also cause a certain depth of damage to the metal surface, so that the damaged metal surface cannot be cleaned by pickling, electropolishing or shot blasting (such as dry sand blasting and glass beads for abrasives). Rough surface may be the origin of corrosion and deposition products, and it is not allowed to use rough grinding to clean weld defects or remove redundant weld reinforcement before re-welding. In the latter case, fine abrasives should be used for grinding.

7, welding arc spots

When the welding machine arcs on the metal surface, it will cause the surface roughness defect. The protective film was damaged, leaving a potential corrosion source. The welder should strike the arc on the weld bead or the side of the welded joint. Then the arc trace is melted into the weld.

8, welding spatter

Welding spatter has a great relationship with welding technology. For example, GTAM (gas shielded tungsten arc welding) or TIG (inert gas shielded tungsten arc welding) has no splash. However, when GMAW (gas shielded metal arc welding) and FCAW (flux-cored wire arc welding) are used, if the welding parameters are not used properly, a lot of spatter will be caused. When this happens, the parameters must be adjusted. If we want to solve the problem of welding spatter, we should apply splash inhibitor on each side of the joint before welding, so as to eliminate the adhesion of spatter. After welding, anti-splash agent and various splashes can be easily removed without damaging the surface or causing slight damage.

9. Flux

Welding processes using flux include manual welding, arc welding with flux core and submerged arc welding. These welding processes will leave fine flux particles on the surface, which cannot be removed by ordinary cleaning methods. This kind of particles will become the corrosion source of crevice corrosion, and these residual fluxes must be removed by mechanical cleaning.

10, welding defect

Welding defects such as undercut, incomplete penetration, dense pores and cracks not only reduce the firmness of the joint, but also become the corrosion source of crevice corrosion. In order to improve this result, they also carry solid particles during cleaning operations. These defects can be repaired by re-welding or re-welding after grinding.

1 1, oil and grease

Organic substances such as oil, grease and even fingerprints will become the corrosion source of local corrosion. Because these substances can play a barrier role and affect the chemical and electrochemical cleaning effect, they must be thoroughly cleaned. There is a simple waterproof test for
TM A380 to detect organic pollutants. During the test, water is injected from the top of the vertical surface, and in the process of downward flow, water will separate along the periphery of the organic matter. Flux and/or acidic chemical cleaning agent can remove oil and grease.

12, residual adhesive

When the adhesive tape and protective paper are torn off, a part of the adhesive always remains on the stainless steel surface. If the glue is not hard, it can be removed with organic solvent. However, when exposed to light and/or air, the adhesive hardens, forming a corrosion source of crevice corrosion. Then mechanical cleaning with fine abrasive is needed.

13, printing with pigment, chalk and marker.

The effects of these pollutants are similar to those of oil and grease. It is recommended to use a clean brush and clean water or alkaline cleaning agent, or use high-pressure water or steam for cleaning.