External coating is a typical three-layer system consisting Fusion Bonded Epoxy, Polyethylene Layer and a Adhesive layer.
The Fusion Bonded Epoxy Layer is applied for the purpose of anti-corrosion protection. The adhesive layer sticks the Polyethylene Layer to the Fusion Bonded Epoxy Layer. The Polyethylene Layer protects the Fusion Bonded Epoxy Layer against impact during transportation and pipe handling.
Pipes are placed on the incoming skewed roller conveyor and transported to the heating system where the pipe will be preheated to the appropriate temperature. Using intermediate conveyors, the pipe will then be transported through the coating application area where the three-layer coating can be applied. Pipes will be separated immediately after coating and then cooled down on the cooling conveyor with a controlled volume of recirculating water. The outgoing conveyor will move the pipe to the ejection arms for ejection onto the skidways for inspection and end-cleaning.
The components that are supplied for the application of the coating materials are designed to be used to apply multi-layer type coating in accordance with the coating material manufacturers and Buyer's specification.
A typical system consists of the following:
- Incoming Skidways
- Feed-in and Lower-in Units
- Incoming Skew Conveyor
- Vacuum Dust Removal System
- High Pressure Water Wash Unit
- Inorganic Chromate Application System
- Pipe Heating System
- Intermediate Conveyor (between coil and coating section)
- Fusion Epoxy Powder Application and Reclaim System
- Copolymer Extrusion System
- PE/PP Extrusion System
- Water Cooled Pressure Roller with Weld Seam Sensor
- Control and Monitoring Console for Coating Systems
- In-Line High-Voltage Holiday Detector
- Cooling Skew Conveyor
- Pipe Cooling Tunnel
- Outer Cooling System
- Outgoing Skew Conveyor
- Padded Pipe Ejection Units
- Electric Hydraulic Power Unit
- Intermediate Padded Pipe Skidways
- Pipe End Cleaning and Cutback Beveling Machine
- Outgoing Skidways
- Components for Quality Control and Inspection Equipment
- 20-Foot Tool Container
External Coating Systems
External Surface Cleaning
The external blast cleaning system is designed to clean the external pipe surface with steel shot, grit or a combination of both, in preparation for coating. Degree of cleanliness is controlled by the speed of pipe transferred through the surface preparation system.
End Cleaning Stations
This station is designed to clean coating material from the ends of freshly coated pipe to provide a smooth transition between the factory applied coating and the joint coating applied in the field. Machines can be adjusted to provide cutback from 3-9" (76-229 mm).
Coal Tar Enamel Coating
This system is designed to apply a suitable Coal Tar Enamel (CTE) on the external pipe surface, per AWWA, or BS coating specifications. This CTE coating system is used for corrosion protection of Oil, Gas and Water pipe lines, with longitudinal or spiral welded seam.
External Single Layer FBE Coating
This system is designed to apply a suitable Fusion Bonded Epoxy on the external pipe surface, per AWWA, or BS coating specifications. This FBE coating system is used for corrosion protection of Oil, Gas and Water pipe lines, with longitudinal or spiral welded seam.
External Tape Coating
This system is designed to apply a polypropylene type tape, hot or cold applied, on the external pipe surface, per AWWA, or BS coating specifications. This tape coating system is used for corrosion protection of Oil, Gas and Water pipe lines, with longitudinal or spiral welded seam.