Chemco Case Studies

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Preventing Stress Corrosion Pitting

Industry                     

Mineral Processing

 

Date

2007

 

Substrate

304 Stainless Steel – Ammonia absorber and circulation tank.

 

Products

Chem-tect™ RF364 – vinyl ester / acrylic co-polymer enhanced with flaked glass; very suitable for immersed environments where superior resistance to chemical attack is required.

 

Environment             

Normal operating temperature is 60-70°C. Excursions up to 100°C are common.

• Wet ammonia gas

• Diluted sulphuric acid (up to about 20%)

• Ammonium sulphate

• Naphthalene

• Benzene

• Aromatic and aliphatic hydrocarbons

• Hydrogen sulphide

• Hydrogen cyanide

 

Challenge

Prevent Stress Corrosion Pitting in the heat effected areas, these are generally found either side at the toe of the weld. Apply corrosion protection on the entire internal surfaces within a 72 hours outage.

 

Chemco’s Solution

Abrasive blast to Chemco Specifications and 3 coats of Chem-tect™ RF 300 Series.

 

Scope                        

Recommend the entire internal surfaces are treated.

Mobilise on site.

Set up of dust containment only.

Set up of De-humidification equipment.

Abrasive blast to Chemco Standards.

Application of a Chem-tect™ RF 300 in 3 coats including strip coat all difficult to reach areas.

De-mobilise from site.

 

Site Layout before equipment setup
Site Layout before equipment setup
Previously applied coatings delaminated
Previously applied coatings delaminated
Ammonia Absorber
Ammonia Absorber
Circulation Tank
Circulation Tank

 

Results

The best outcome the asset owner has obtained after years of trials using various epoxies and fibreglass linings. The combined large anchor profile achieved while abrasive blasting and excellent permeation resistance of the glass flake filler has proven itself again.

 

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