Step-01 Primer Application
Prior to start fusion bonded epoxy application,the primer will be applied on the internal surface using an internal air spray machine.The oven will be preheated and temperature should be maintained in 180°C for at least 20 minutes prior to loading of primed materials.
Primer thickness will be 15 to 25 micron or as recommended by manufacturer.The primed items will be inspected visually to ensure that primer is applied uniformly and covered entire area of the surface to be coated.It is not possible to measure accurate DFT readings as it has a surface profile of 50-100 microns.
Primed materials should not be kept more than 4 hours without fusion bonded epoxy coating inside the oven at maximum pre-heating temp.of 232°C.If prolong strong of primed items are required over 5 hours,both oven ends of the pipe/spool will be kept closed with suitable plastic covers in conformance to the coating manufacturer’s recommendation.
Step-02 Pre Heating
The primed materials shall be preheated to the required temperature in a temperature controlled gas burned oven.
Preheat the items to be coated to substrate temp.of 177°C -210°C for 30 minutes as per manufacturer’s recommendations,
The substrate temp.is measured by a suitable temperature measuring gauge which is directly connected to the substrate and shows the metal temp.
Step-03 Fusion bonded epoxy powder coating.
Once items preheated to the required temperature ,the fusion bonded epoxy powder will be uniformly applied to the preheated surfaces by Flocking according to the pipe configuration.It can be done by manual application or semi-automated lance system.
FBE Powder application will be done only after the 30 minutes of pre-heating temperature at 177°C -230°C on the primer.Temperature of pre-heated primed surfaces will be measured with IR thermometer before & during FBE application.
The temperature FBE coated surface after immediate application should not be less than 177°C.Those FBE coated spools with temperature less than 177°C reprocessed after completely removing the existing coating.
In manual application,All applicators should be trained and certified by the coating manufacturer and will be qualified by client.
Sample plate will be loaded in the oven along with eatch batch of spools.
Step-04 Post Curing.
The pipe fittings should be post cured after the coating application to achieve full cure and maximum performance properties.It will be done immediately after the FBE coating application.
The curing schedule as per manufacturer’s recommendation as given below.
Post cure temperature (Substrate)-204°C-220°C – (399°F-428°F)
Post cure time – 50minutes +/-10minutes.
Start and end time for post curing recorded in the FBE application format.Daily oven temperature log submitted to client representatives at site.
After the coating has cured in accordance with the time/temperature requirements of the coating manufacturer,the coated items will be left for cooling at ambient conditions.Inspection and repair may start after the item has cooled to 93°C or below.