This procedure is use for garnet blasting and painting of Carbon Steel (CS) valves, flanges and its adjacent parts.
2. Purpose
To ensure that carbon steel substrates are properly blasted and painted in accordance/equivalent to the painting specification COM.SU 2.02A
& COM PAPH 36-2.02A
3. Surfaces Preparation
3.1 Prior to painting, all surfaces shall be checked/cleaned and free of oil, grease, dust, rust, mill scale and other foreign materials.
3.2 All non ferrous material shall not be blasted or painted, unless otherwise instructed and should be protected.
3.3 Gauges, screw threading, name plates, gasket and opening to internal surfaces shall be masked / taped up before blasting and painting.
3.4 As per 4.15 - Preparation for Abrasive blasting : Chloride, Sulfate & Nitrate test shall be carried out on the abrasive blasted surfaces
prior to coating.
4 Blasting Equipment / Materials
4.1 Materials :
4.1.1 The blasting abrasive material will be Garnet 30-60 sieve series to provide an anchor profile height of between 1.5- 2.5 mils (37.5-62.5 microns).
4.2 Blasting Equipments :
4.2.1 Blasting Equipment shall be provided with automatic moisture trap and drains.
4.2.2 Air fed hood will be used and have appropriate filters on air.
4.2.3 The pressure vessel used for blasting must be checked and ensured to withstand the blasting pressure.
4.2.4 Compressor air used for blasting shall be free from water and oil.
4.2.5 Hoses shall be static dissipating.
4.3 Personnel (Painter & Blaster):
4.3.1 ONLY qualified personnel shall be employed to carry out the blasting & painting operation.
5. Painting Application
5.1 Method of Application shall be spray except for " Touch-up " painting which can be done on roller / brush.
5.2 Coating shall be carried out under the following conditions:-
a) Air temperature is > 30°C
b) Surface temperature is > 25°C
c) When the Relative Humidity (RH) < 85%
d) When the surface temperature is less than 3°C above Dew Point.
5.3 Refer to customer's specifications on the type of paint to use.
5.4 A stripe coat shall be applied to areas such as corners, welds, edges, bolt holes and all other areas hard to spray prior to application
of the specified coat.
5.5 Check the substrate surfaces to ensure that it is thoroughly dry and free of dust before applying any coating. 1st ooat of primer shall be
applied within four hours after blasting.
5.6 All coatings shall be allowed to dry or cure thoroughly for the specified time as per coating manufacturer's technical data.