A lining process is where corrosion resistant materials are adhered to the inside of steel plating vessels and material transfer pipes in order to protect from corrosions. The thickness of the linings are normally several millimeters as opposed to 100 to several hundred micro-meters of painting, and the linings offer superior chemical stability and mechanical strengths compared to those of paints.

Surface treatment processes such as plating, etc. use various tubs such as plating tubs, de-greasing tubs, electrolytic tubs, neutralizing tubs, and washing tubs with strong acids, alkali, and highly oxidizing solutions. The tubs are made of steel to support the weights of these chemical solutions and subject materials. These tubs are lined with corrosion resistant linings to prevent the tub structures from corrosions and contamination of the contents.

[Table 1] shows currently used corrosion resistant lining material in frequent use. The linings are selected based on chemical resistance applicability.
In addition to the corrosion resistant characteristics, specific gravity and thermal conductivity are of significant importance. Low specific gravity equates to light weight for easier handling during the lining installation processes which also reduces overall costs. Lower thermal conductivity of the linings as compared to that of steel (48.3w/m-k) means the process liquid temperatures are maintained better.

[Table 1] Corrosion Resistance Comparisons of Lining Materials

Material Corrosion Resistant FRP Vinyl Chloride Neoprene Rubber Polypropylene Physical Properties Specific Gravity 1) 1.4-1.8 1.45 1.64 0.91 Tensile Strength 2) 85-180 50-60 20-35 25-380 Thermal Conductivity 3) 0.2558 0.1512 0.1163 0.0930 Corrosion Resistance Formic Acid 50％ or Less 40℃or Less Chloroacetic Acid 60℃ or Less Dilute Sulfuric Acid 60℃ or Less Concentrated Sulfuric Acid 90% or Less 60℃ or Less Norm. Temp. 50％ or Less Hydrochloric Acid 60℃ or Less Phosphate 60℃ or Less Chromic Acid 30％ or Less 60℃ or Less 3％70℃ or Less Hydrofluoric Acid 10％ or Less 25％ or Less Caustic Soda 50％ or Less 60℃ or Less 50％ or Less Ammonia Water 30％ or Less Sodium Hypochlorite

※	Note 1) g/cm3、Note 2) Mpa/mm2、Note 3) w/m・k、Good Corrosion Resistance、Poor Corrosion Resistance