Pipes may be coated externally to be protected from corrosion, erosion and possible mechanical stress.
Pipe coating consists of the application of metallic, or non-metallic, materials on the external surface of the pipe (either seamless or welded).
The most common materials to coat pipes externally are:
Non-metallic pipe coating: Paints, varnishes, lacquers, bituminous coatings, resins, plasticizers, Greases, waxes, oils, Plastics (polyurethane, polyethylene, Rilsan, PTFE, PVC), Elastomers (various types), Vitreous enamel, Cement mortar
Organometallic pipe coating: Paints pigmented with metals in powder form (aluminum, zinc, lead, stainless steel), Paints containing zinc ethyl-silicate
Chemical modification: Phosphating, Chromatin, phosphating, Black finishing, and browning
Cementation (physiochemical modification)
The main types of non metallic pipe coating materials, and their advantages/disadvantages, are summarized in the table below:
| Pipe Coating Type | Advantages | Disadvantages |
| Three-layer Polyethylene (3LPE) and 3 layers Polypropylene (3LPP) | Low material and application cost |
|
| Polypropylene (PUR) | Recommended for deep sea applications with relatively high temperature and pressures | Polypropylene is liable to chain degradation from exposure to heat and UV radiation such as that present in sunlight. |
| Fusion Bonded Epoxy (FBE) | Excellent chemical resistance and great dimensional stability with minimized hysteresis |
|
| Asphalt enameled and polyurethane (PUR) | Cheap and superior to coal enamelReduces the hysteresis Fast treatment |
|
Post time: May-09-2022