Advanced Polymer Coatings For Chemical and Corrosion Protection

Baghouse Internal & Doors In Cement Plants

By ProCoat High Performance

Coating Systems

Chemical - Abrasion -Temperature Induced Corrosion Protection Of

Chemical Corrosion Over Bag House Doors & Internal Surface

Chemical corrosion of Bag House metal substrate Frequent start and stop of kiln, false air ingress through the rotary air locks and doors of bag house, operation of bag house close to the dew point, poor gas distribution and emission of sulphurous gases are the major concern to induce corrosion of bag house internal surface and doors. In-spite of having excellent design and the efficiency of kiln, acid producing compounds from the fuels used to fire kiln, chlorides from raw material and saline ambience which are in gaseous and crystalline form, water vapour from the combustion of fuel and inherent moisture in the kiln feed or through the false air ingress, facilitate localized condensation of water and acid over metal surface of bag house when the gas temperature reduces or nearing to 20

oC of the dew point. Chemical reactions in the presence of water vapour (moisture)

lead to form sulphurous, sulphuric, hydrochloric acids and in turn react with Iron to form ferrous sulphate, ferrous chlorides which are nothing but chemical corrosion products of iron in the form of thick layers. Since these chemical reactions take place on continuous basis, gradual loss of metal thickness is observed and formation of holes specifically in doors that facilitate further ingress of moisture and salts which lead to acceleration of chemical corrosion of metal.

Secondly, during the operation of bag house, high velocity gases loaded with fine dust particles come in contact with doors as well as internal surface causing impact and abrasion. This action lead to removal of the formed corrosion products and exposure of fresh surface to the chemical corrosion. Thirdly, deposition of layers of dust over metal with a content of moisture forms excellent conductive electrolyte on permanent basis facilitating continuous chemical corrosion of mild steel bag house surface. The shown photographs are revealing the explained parameters like “deposition of dust in layers”, “severe degree of metal corrosion beneath these layers”, “formation of holes in doors” of the inspected bag house. Since the process parameters and operating conditions cannot be altered in the bag house, protection of metal surface of doors and internal frame area (which are more prone for corrosion due to complex shape and welded nature) is found to be necessary to take up on priority basis keeping in mind the present severe deterioration pattern into consideration. ProCoat Specialities has proven solution with 100% solids, solvent free, advanced, 2.8 functionality hybrid Novolac pure epoxy coating system designed with excellent chemical and temperature resistance along with high end engineered strengths to address chemical attack, temperature exposure, abrasion problems by forming a high performance barrier lining over internal surface of bag house. It is obvious that a high performance coating system should be applied with utmost care and quality over bag house surface to meet both protection requirement and value to the money spent by clients. ProCoat has hands on experience in work execution by their trained service team and take up work on turn-key basis by implementing stringent surface cleaning & quality checking method.

Typical Observed Corrosion Problems In Bag House Internal

ProCoat - Experience In Protecting Bag House Internal & Doors

Protected Bag House With ProCoat Coating System

Surface Preparation Of Baghouse Internal By ProCoat Service Team At UTCL-Sewagram

ProCoat - Experience In Protecting Bag House Internal & Doors

At UTCL-Kovaya

Corroded Baghouse Internal Surface

Surface Preparation Of Baghouse Internal By ProCoat Service Team

ProCoat - Experience In Protecting Bag House Internal & Doors

At UTCL-Kovaya

Protected Bag House With ProCoat Coating System

Evaluation of applied ProCoat coating at UTCL-Kovaya in the recent opportunity

In the recent opportunity of shutdown, applied ProCoat coating system over internal surface of Bag house was inspected by wiping the accumulated dust and wet cloth cleaning to expose the coated surface at few areas and found ProCoat coating in excellent condition without any signs of change in surface texture, no signs of rust spots, no erosion of coated surface on account of chemical attack, no physical changes on account of high wet temperature exposure and offering best protection to bag house internal walls.

ProCoat - Experience In Protecting Bag House Internal & Doors

At Ambuja Cements Limited

At Ambuja Cements Limited

ProCoat - Experience In Protecting Bag House Doors

At Zuari Cements Limited

In short shutdown of plant, few bag house doors which are heavily corroded were taken up for protection with ProCoat system. Thorough mechanical grinding done over doors to remove existing thick chemical corrosion deposits, further wet sponge cleaning done to remove the adsorbed chemical contamination and then applied ProCoat advanced hybrid Novolac Epoxy coating system by synthetic roller over prepared surface of bag house doors. Further quality checks like film thickness, film integrity completed before putting into operation.

During recent inspection of ProCoat applied bag house door by user, coating was found in excellent condition even after exposure of corrosive medium for more than one year. Un-protected areas are undergoing rapid chemical corrosion as seen in photographs.

Performance Evaluation Of Applied ProCoat Coating Over Internal Surface Of Bag House Doors

Medium Exposed : Sulphuric Acid, abrasive dust, 150 deg C temperature Coating Applied In : 2006 Coating Inspected In : 2015 Period Of Observation: 9+ years

In the year 2015, during an opportunity i.e., after 9.5 years, same bag house door was inspected after removing accumulated dust and found applied ProCoat coating is in intact condition without allowing chemical corrosion to bag house door, even no permeation has taken place from the edges of coating. Due to long term exposure of coating to high temperature, only colour of coating changed without any change in functional / chemical resistance characteristics, thus making a reliable and dependable solution to bag house doors as well as internal walls of bag house.

At UTCL-Kovaya

Credential

ProCoat Coating System Specifications Recommended For Bag House Internal Protection

Intended Purpose

For retaining DIMENTIONAL STABILITY of equipment without metal deterioration on account of chemical corrosion

Bare minimal maintenance in the assured protection periods without underneath corrosion

Absolute metal protection in the given harsh chemical & high temperature exposure

Enhancing the life of costly and critical bag house To meet this “Bag House Metal surface has to be isolated from the physical & electrical contact of corrosive electrolyte by applying ProCoat–1751 coating for resisting ingress of chemical molecules, effect of variable temperatures and abrasion caused by high velocity dust particles over metal substrate for extended periods”

Coating System : ProCoat - 1751 2.8 Functionality 100% Solids Hybrid Polymer Novolac Coating Ceramic Carbide And Zirconium Filled For High Aggressive Acid And Alkali Environments With Elevated Temperatures And Abrasion Chemistry & Curing Mechanism : ProCoat - 1751 is a solvent free, 100% solids, ceramic filled high functionality Novalac with amine cured coating system designed for protection of metal and concrete in immersion and non immersion service where environments are highly aggressive , particularly in high chemical, abrasive and high temperature environment. Superior multi-functional chemistry of ProCoat - 1751 produces a tough coating system having excellent engineering properties to offer high corrosion and abrasion resistance to metal and concrete by forming a highly impermeable, three dimensional complex, high density cross linking polymer matrix structure which prevents attack and permeation of aggressive chemical, corrosive or moisture molecules even in elevated immersion temperatures.

Dry Temperature : 204 oC , Spike (3 hrs) 232

oC

Humidity Resistance : Tested up to 5000 hours Salt Fog Resistance : Tested up to 5000 hours Water Vapour Permeability 0.03 g-mil / 100 in2 / 24 hrs Impact Resistance : 2.56 ft lb / in Shelf Life : 5 years Full Cure : 36 hours at 32 deg C Chemical Suitability Raw Water, Sea Water Excellent Alkalis Excellent Inorganic Acids Excellent Organic Acids Excellent Organic Solvents Excellent

Engineered Properties Volume Solids 100% Volatile Organic Compounds Nil Hardness 87 Shore D Ultimate Tensile Strength 6,000 psi Ultimate Flexural Strength 8,900 psi Abrasion Resistance-CS17 0.07 ml loss/1000 @1kg Compressive Strength 14,700 psi Tensile Shear Adhesion 2,200 psi Pull Off Adhesion 2,000 psi Viscosity, cps 65,000 - 85,000 Thermal Conductivity 0.64 K Cal / m hr

oC

Immersion Temperature 130oC,Spike(3 hrs)204

oC

Method of Work Execution:

Arrangement of scaffolding system inside Bag House to access all sides including roof and floor

High pressure air cleaning to remove the dust along with suction arrangement to reveal the rusted surface

Carrying out of initial copper slag blasting to remove existing corrosion layers

Checking of acidic contamination with pH, Litmus, Silver Nitrate, Potassium Ferricyanide test methods

Identified contamination to be removed by either alkaline wash by scrubbing the surface till it foams

High pressure water washing to remove both acidic and alkaline contamination so that surface become neutral

Checking of surface again to ensure “contamination freeness”

Carrying out of chilled iron grit blasting to achieve “white metal finish” as per Swedish Sa3 standard and matched with shade card and recorded

Measuring of achieved surface profile i.e., roughness by Elcometer profile gauge and to ensure an average 125 microns roughness on surface which facilitate polar-polar, chemical bonding and mechanical interlocking of coating with substrate

Application of ProCoat-1751 coating system in two spells with a tack free state interval to build the recommended thickness. Being 100% solids in nature, both wet film and dry film thickness remains same without any shrinkage.

Measuring of dry film thickness reading on cure for fixing the voltage in porosity / holiday detector.

Carrying out of coating integrity check with Holiday tester on entire coated surface including edges and intricate areas. If any missing found, same will be marked and touched up with fresh coating material.

Final cure test with MIBK

Adhesion test with pull off adhesion tester either on coated surface or a specimen prepared during work execution.

Forced curing by placing either halogen lamps or indirect heating of coating to attain full cure properties.

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Registered Office 202, Kruti Commercial Complex, Opp. Jai Ganesh Auto Centre, Near Balaji Temple, 150 Feet Ring Road, Rajkot - 360 005 (Gujarat) India. Phone: +91-281-6540162, 2589355 Fax : +91-281-2589155

For Further Information Contact

E-mail: info@procoat-india.com Website: www.procoat-india.com