1.Steel Type Selection

Stainless steel must be selected according to usage and environment in order to extend the life cycle and sustain its fine surface.

Type \ Environment Suburb City Industrial Area Coastal Area I L M H I L M H I L M H I L M H High Corrosion Resistant STS ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ STS316 ◎ ◎ ◎ ◎ ◎ ◎ ● ● ◎ ● ● ◆ ◎ ● ◆ ■ STS304 ● ● ● ● ● ● ◆ ◆ ● ◆ ◆ ■ ● ◆ ■ ■ STS430 ● ● ◆ ◆ ● ■ ■ ■ ◆ ■ ■ ■ ◆ ■ ■ ■ Examples I (Indoor Environment): Indoors L : Lightly corrosive environment (low temperature, high humidity) M : General environment H : Severely corrosive environment (high temperature, high humidity) ◎ over qualit y, ● appropriate, ◆ usable if cleaned often, ■ inappropriate

2. Storing and Transporting

Stainless Steel has good corrosion resistance because the surface has a passive layer and needs to be handled with care to maintain the passive layer.

Storing

When storing, it is important to avoid exposure to moisture, dust, oil, and lubricant in order to prevent rust and lowered corrosion resistance when welding. When moisture is introduced between the protective film and stainless steel, corrosion rate is faster than without protective film. Store in a dry and well ventilated place preferably in the original package covering. Materials with protective film should be kept away from direct sunlight and the film should be inspected regularly. If the film shows signs of deterioration (film lifespan is approx.3 months), it should be replaced immediately. When packaging materials including paper get wet, they should be removed immediately to prevent surface corrosion.

Transporting

When transporting, rubber or wood support/underpinning should be used to avoid surface scratching. Special stainless handling equipment should be used. Gloves should be worn to avoid smudges from fingerprints.

3. Fabrication and Construction

Cutting and Pressing

For punching and shearing, more pressure is required since stainless steel has higher strength compared to mild steel. When cutting, the clearance between the dice and punch should be precise to prevent work hardening or burr. Plasma or laser cutting is recommended. If gas or arc cutting is unavoidable, grinding and heat treatment must be applied to heat affected zone, if necessary.

Bending

The sheet under 2mm in thickness can be bent for 180° flat working. However, to reduce cracking of bent areas, it is recommended that the sheet with the same inner radius as the thickness be applied. When bending in rolling direction, the sheet over 2mm in thickness should have the curvature radius twice the thickness. When bending in transverse direction, the curvature radius for sheets over 2mm in thickness should be 4 times the thickness. To prevent bending cracking of the welded areas, surface grinding is recommended.

Drawing

When deep drawing, friction and surface damage is likely to occur. Therefore, lubricants must be pressure resistant and heat resistant. After drawing, molding lubricant on the surface must be removed thoroughly.

Welding

Grease, moisture, and paint should be removed to enable welding. The wires or electrodes suitable for each steel type must be selected. When tack welding, pitch must be shorter than carbon steel and, when removing slag, stainless brush must be used. After welding, grinding treatment and cleaning process are needed to prevent local corrosion and diminished strength.

Construction

Stainless steel is shipped with a protective film to prevent scratching or contamination, but deterioration and problems related to adhesive residues can occur. When removing film after fabrication, surface must be cleaned. Stainless steel exclusive tools should be used and, when used on other steels, the tool must be cleaned thoroughly. Make sure that highly corrosive cleaning detergents for tiles and stones do not come in contact with the stainless steel surface. When stainless steel comes in contact with such materials, it must be cleaned immediately. At construction sites, stainless steel should not be exposed to cement and dust. After construction, the stainless steel must be cleaned with neutral detergent and water. Pay special attention to handling since chemically colored, etched, painted and coated materials are susceptible to discoloration and surface scratches, and repair work is difficult.

4. How to Clean the Surface

To maintain the characteristics of stainless steel and to prevent rust, regular cleansing and maintenance is necessary. Avoid surface scratching and using detergents with bleaching agents. Use scrubbers and polishing tools and rinse with clean water.

Cleaning Intervals According to Environment and Area

Environment Suburban Area City, Industrial and Coastal Area Area Structure Normal Environment Corrosive Environment (high humidity, air pollution) Exposed to moisture No residues of contamination and sediments 1~2times/year 2~3times/year 3~4times/year Residues 2~3times/year 3~4times/year 4~5times/year Not exposed to moisture No residues of contamination and sediments 1~2times/year 3~4times/year 4~5times/year Residues 2~3times/year 4~5times/year 5~6times/year

Surface Conditions and Cleaning

Surface Condition How to Clean Dust and other stains Use soap, soft detergent in warm water Labels and protective film Use soft detergent in warm water, and use alcohol or organic solvent for adhesives. Fat, oil, grease contamination/stains Use soft cotton or paper, then use neutral detergent or ammonia solution/solvent or use special detergent chemicals. Bleaching agent and other acidic adhesive Rinse with water immediately, soak in ammonia bicarbonate soda solution and clean with warm water or use detergent Carbon organic and inorganic substances, carbon adhesion Soak in neutral detergent or ammonia solution/solvent before cleaning, use detergent with polishing material Fingerprints Use organic solution (ether or benzine) on cotton and rinse with water. Rainbow pattern Usually caused by over use of detergent or oil. Use warm water and neutral detergent. Discoloration after welding Clean with 10% of nitric acid solution or non-oxalic acid, neutralize in ammonia or bicarbonate solvent or water. use special detergent products. Rust from surface contamination Clean with oxalic acid, sulfur acid, nitric acid(10%)or polishing detergent. Use special detergent products.