High build epoxy coating surface preparation.
All Surface imperfections such as weld spatter, slag, sliver, sharp surfaces etc. shall be removed by wire brushing, grinding and / or filling prior to abrasive blast cleaning.
Oil, grease etc. will be removed by solvent cleaning in accordance with SSPC-SP-1 or high pressure washing or detergent cleaning.
The cleaned surface shall be allowed to dry before proceeding with further preparation or coating. If Surface moisture present, it shall be removed by appropriate equipment immediately prior to coating.
Abrasives shall be selected from Client approved VEC list and each batch of abrasive shall be client approved prior to its use.
Blast cleaning (Grit abrasive) material shall be Garnet giving a surface profile of 75-125 microns as recommended by the manufacturer.
The surface shall be blast cleaned to SIS 055900 SA 2 ½ (SSPC-SP-10) (Very thoroughly blast cleaned) mill scale, rust and all other foreign matter shall be removed to the extent that the only traces remaining are slight stains in the form of spots, or strips as shown by the appropriate colour photographs (ISO 8501-1) in the standard.
Laminations shall be repaired or removed by power tool by brass cup brush. This repaired area and other surface defects, missing spots etc. shall be re blasted to achieve the required profile.
All blasting pots, coating units and compressor shall be fitted with efficient water/Moisture separator and water traps etc.
If manual blasting, Tungsten carbide ventury type blasting nozzles shall be used.
High build epoxy coating shall not be applied on the location intended for blasting.
Surface profile shall be checked by using PRESS-O-FILM and measurement recorded on painting report.
After blasting surface immediately before High build epoxy coating chloride content level shall be tested which shall be less than 5 µg/cm² tested with Bresele or Chlor test Kit as per EN ISO 8502-06 and EN ISO 8502-09 respectively.
All spent abrasive shall be removed from surfaces by blowing dry compressed air or brush before priming.
Dust embedment on the blasted surface shall not be greater than Grade 2 as per ISO 8502-3.
All surfaces preparation shall be inspected prior to any high build epoxy coating being applied.
High build epoxy coating shall be applied on blasted surface before rust blooming occurs or within 4 hours of blast cleaning, whichever is sooner.
High build epoxy coating weather conditions.
High build epoxy coating and Blasting shall not be carried out during rain or wet weather. Climate conditions shall be measured and recorded prior to blasting and coating operations at time intervals.
No Painting/coating shall be allowed during:
a. Sand storms or dusty weather.
b. Surface temperature of steel shall be minimum 3°c above dew point or when the ambient temperature is less than10°C.
c. The relative humidity is 85% or higher or at any lower relative Humidity stipulated by the paint manufacturer.
d. If metal surface temperature is above 50°c.
e. Under adverse weather conditions (i.e. rain, fog sand storm, high wind velocity 56 km/hr or higher) or such conditions are likely before the paint/coating has become dry.
High build epoxy coating application.
The High build epoxy coating material shall be in full compliance with the client standards and manufactures recommendation.
All materials shall be factory packed and delivered to the work site in their original sealed containers with the manufacturer’s batch number, date of manufacture, shelf life expiry date and manufacturer’s name.
Batch certificates shall be provided for all high build epoxy coating materials. Batch certificates for coating materials shall be checked against material at time of receipt. Contractor QC inspector shall prepare material inspection report and shall be offered for the clients/TPI inspection of the high build epoxy coating materials.
Materials which have exceeded the shelf life recommended by the manufacturer shall not be used.
All High build epoxy coating materials shall be stored as per the manufacturer’s recommendations.
Surface to be painted/coated shall be free from dust and contaminants before application.
The high build epoxy coating shall be applied with airless spray equipment as per manufacturer’s recommendation.
The pot life & the expiry date of paint along with certificate shall be checked prior to use.
High build epoxy coating shall be done as soon as possible after blasting to prevent oxidation of newly blasted surfaces. In case of contamination remove contaminants by spot blasting if needed. The interval time between abrasive blasting and application shall not be more than 4 hours.
The mixing ratio of the two component materials shall be in accordance with the paint Manufacturer’s specification.
For containers larger than 5 Liters, Mechanical paint agitators or rotary mixers shall be used.
To achieve correct viscosity of paint the thinner recommended by manufacturer shall be used and manufacturer’s instruction shall be followed.
The coated cut back length shall be 100 mm from end of the pipe.
Weather condition will be monitored all the time and will be recorded in the log book.
High build epoxy application.The paint shall be uniformly applied to the prescribed wet film thickness in order to achieve required dry film thickness. Applied paint shall be free from sags, runs and marks. Minimum and maximum over coating interval between coats in accordance with the manufacturer’s instruction shall be adhered to.
The curing method, temperature and intervals shall be monitored for compliance with the manufacturer’s recommendations.
Total DFT required shall not be less than 750 microns and not greater than 1500 microns. The recommended dry film thickness shall be achieved in one single coat.
For External Surface
|Paint Code||Interzone 485||Carboguard 703|
|DFT||750 -1500 µm||750 -1500 µm|
High build epoxy coating shall be in one coat. Brush shall be used for one time to eliminate the possibility of contamination for external surface. If necessary roller shall be used at the end of the pipes, spools and fittings based on the conditions.
Where the mill applied coating cannot be extended above ground level, High build epoxy application shall be applied. For those areas of the pipes located in the soil to air interface, the underground main line coating shall be extended to at least 300 mm and shall not exceed 750 mm above the ground level.
The cured coating shall not be exposed to the direct UV radiation for more than the limits imposed by manufacture written recommendation.
Areas which exhibit paint defects such as improper bonding; insufficient coating thickness, blistering or damage during transit or erection shall be repaired using painting/ lining material identical to or compatible with the original coated material.
The selection of suitable surface preparation shall depend on the size of the defect to be painted/ coated.
Defect less than 50 mm² in size shall be prepared by a power tool disc grinder. All sides of the adjacent damaged coating shall be roughened up to 50 mm.
Defects between 50 mm² up to 150 mm² in size the defective area shall be spot grit blasted to achieve the required surface cleanliness and profile. All sides adjacent to the abrasive blasted coating shall be roughened for s distance about 50 mm.
For the defect larger than 150 mm² in size, items shall be abrasive blasted and completely recoated.
High build epoxy application,Repair Epoxy system shall be applied on the prepared area and the adjacent coating in accordance with manufacturer’s recommendation. Repair area shall overlap minimum of 50 mm to surrounding sound coating.