Most common coatings
External FBE Coating
Fusion Bonded Epoxy (FBE) coating protects pipe surfaces against corrosion. Double or triple layers of FBE may even increase the resistance to friction and abrasion. FBE coating is also used as the primer layer in 3-layer PE/PP coating systems.
Electrostatic epoxy powder is sprayed onto a pipe at a temperature typically around 220 – 235°C. On reaching the hot pipe surface, the epoxy powder melts and forms an uniform layer of epoxy coating on the pipe.
- Acid wash
- Induction heater
- FBE application system
- Cooling or quenching station
- Holiday detection
3 Layer PP/PE Coating
In addition to an anti-corrosion layer of FBE coating, mechanical protection can be added by applying a layer of Polyethylene (PE) or Polypropylene (PP). An adhesive layer takes care of the bonding between the FBE and PE/PP layer.
Granules of PE/PP are extruded onto the passing pipe, forming a solid coating layer. Side extrusion is most commonly used, where a sheet of PE/PP is wrapped around a pipe. For smaller diameter pipes, so-called sleeve/ring extrusion is a common process.
- Adhesive extruder or adhesive powder spray
- PE/PP extrusion system
- Weld seam compensator
- Quench tunnel
- Holiday detection
External Liquid Coating
With external liquid coating, coating is applied to the outside pipe surface by a spraying system, providing corrosion protection for the pipe surfaces.
There are multiple coating types available e.g. liquid epoxy, polyurethane (PU), or e.g. (UV-curable) laquer.
Internal Liquid Lining
Internal liquid lining is a coating layer on an internal pipe surface to protect against corrosion or to optimize flow efficiency. There are multiple coating types available such as liquid epoxy, polyurethane (PU), or 2-component coating.
After placing the pipe in the internal liquid coating station, the pipe ends are sealed off and a lance with the spraying gun system is moved through the pipe. Pre-heating could be an option for internal liquid coating.
- Pipe end masking
- Paint pump system
- Liquid coating application system
Internal FBE Lining
An internal FBE coating is used to protect the inner surfaces of steel pipes from the influence of corrosion and light mechanical impacts and it provides excellent resistance to cathodic disbondment.
The internal Fusion Bonded Epoxy (FBE) system is based on an epoxy powder spray system, mounted on a lance. The lance moves through the pipe while the epoxy powder is sprayed onto the internal pipe surface. The pipe must be heated so that the epoxy powder melts onto the pipe. After FBE application, the layer requires curing.
- Primer station (optional, depending on applicable standard)
- Pre-heating system
- Internal FBE coating application system
- Curing oven/chamber
Cement Mortar Lining
Cement Mortar Lining (CML) is a method for applying a mixture of sand, cement and water onto internal pipe surfaces using a centrifugal spinning or pooring method. A smooth and compact layer of cement mortar protects water pipes against corrosion and abrasion.
A characteristic of CML is that blasting the pipe surfaces is not necessarily required prior to the CML application. Selmers has solutions for factory applied and in-situ applied CML.
- Cement mortar batching plant
- Cement mortar application system
- High speed spinning table
- Curing area
Concrete Weight Coating
During the concrete weight coating process, concrete is applied onto the pipe. The concrete layer adds additional weight to pipes to compensate the buoyancy of submarine pipelines, and it also provides protection from external influences.
Impingement: 3LPE/PP-coated pipes with weld cage or wire mesh reinforcement. Concrete is sprayed at the pipe by high speed application drums.
Compression: FBE or 3LPE/PP coated pipes with concrete wrapped around the pipe along with wire mesh reinforcement.
- Pipe buggy system / carrousel
- Wire mesh or caging system
- Concrete mixing/batching plant
- Concrete application equipment (impingement or compression)
- Pipe end treatment
PU Foam Coating
To keep substances in a pipeline at the correct temperature, polyurethane foam (PUF) insulation coating is commonly used for hot oil transmission lines as well as in district heating and cooling.
Pipe-in-pipe application consists of an inner pipe and an outer jacket; the space between them is filled with PUF. Another manner for applying PUF is spraying PUF onto a rotating pipe, with an optional extra mechanical protection layer.
- PUF injectors
- Spray booth
- Jacket system (spiro or PE tubes for pipe-in-pipe application)
- PE extruder in case of PUF
PP Foam Coating
Multi-layer coating with polypropylene (PP) foam providing high thermal insulation; this is used for deepwater pipeline projects. In some cases glass synthetic PP (PP enforced with glass fibre spheres) is used instead of PP foam.
On top of a 3-layer PP coating, various layers of PP foam ensure a pipe gets the insulating characteristics required. Finally, mechanical protection is added with a solid top layer of PP.
- Extruders with gravimetric feeding system for foam application
- Extruder for PP top layer application