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#082 Corrosion Protection Measures - Corrosion Resistant Linings

Category : Corrosion - Corrosion Protection
June10, 2011

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
MaterialCorrosion Resistant FRPVinyl ChlorideNeoprene RubberPolypropylene
Physical PropertiesSpecific Gravity 1)1.4-1.81.451.640.91
Tensile Strength 2)85-18050-6020-3525-380
Thermal Conductivity 3)0.25580.15120.11630.0930
Corrosion ResistanceFormic 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
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