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Pipe Materials, Pipes, Technical Library

Coated, Lined and Clad Pipes

Coated, Lined and Clad Pipes

What is the difference between coated, lined and clad pipes?

 

COATED PIPES

In specific circumstances, pipes are coated externally to be protected from the corrosion and erosion of aggressive environments. The coating consists, therefore, in the application of metallic, or non-metallic, materials on the outer surface of a metal pipe. The most common pipe coatings materials are:

NON-METALLIC

Paints, varnishes, lacquers, bituminous coatings, resins, plasticizers, Greases, waxes, oils, Plastics (polyurethane, polyethylene, Rilsan, PTFE, PVC), Elastomers (various types), Vitreous enamel, Cement mortar

ORGANOMETALLIC

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

PHYSIOCHEMICAL MODIFICATION

Cementation

Coated pipes

The main types of pipeline coatings are:

Pipe Coating Type Advantages Disadvantages
Three-layer Polyethylene (3LPE) and 3 layers Polypropylene (3LPP) Low material and application cost
  • Application of flame in pipeline environments has traditionally been the cause of workplace fires and explosions
  • Requires application of flame to create adhesion
  • Limited heat resistance.
  • Maximum 225°F to 250°F.
  • Limited dimensional stability
  • Features just a borderline hardness
  • Shows poor resistance to sulfur, amines, oxygen and other oxidants.
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
  • Rather expensive application cost per meter
  • FBE materials are expensive
  • The pipe and the coating materials must be heated to approx 250°F
  • Long lead times
Asphalt enameled and polyurethane (PUR) Cheap and superior to coal enamelReduces the hysteresis

Fast treatment

  • Modest resistance to chemical aggression
  • Strict temperature ranges
  • Limited dimensional stability

 

3LPE PIPELINE COATED PIPES

The Three Layer Polyethylene Coating (3LPE) is a multilayer coating featuring three functional components: a high-performance fusion bonded epoxy (FBE), a copolymer adhesive and an outer layer of polyethylene which provides tough, durable protection against corrosion and erosion. 3LPE provides excellent pipeline protection for small and large diameter pipes with medium to high operating temperatures.

 

3LPE pipe coating

(Source: Shawcor Ltd Youtube Channel)

Video – 3 Layer Polypropylene Pipeline Coating (3LPP)

(Source: Wasco Energy Youtube Channel)

 

LINED PIPES

Lined pipes

A lined pipe is a pipe that has been fitted (internally) with a layer of a special material that protects its metal from the erosion and corrosion of the transported fluids.

The lining material is applied at the end of the pipe production process and is mechanically fitted into the pipe. The application of a lining material to a metal pipe reduces the pipe inside diameter. The most common materials used to line pipes internally, and enhance their durability, are:

  • Teflon (PTFE)
  • Cement mortar
  • Liquid epoxy
  • Glass
  • Fusion bonded epoxy (FBE)
  • Polyethylene
  • Bituminous asphalt
  • Zinc

 

CLAD PIPES

A clad pipe combines the strength and toughness of carbon steels with the corrosion resistance of stainless steel (example 316L or duplex) or nickel high-alloyed materials (example Inconel, Incoloy, etc).

The cladding process consists of the application, in the inner part of the pipe, of a layer of higher grade material onto a lower-grade base material of the pipe. Clad pipes are used for fluids that would generate high corrosion on carbon-manganese steels.

The bonding between the two materials is metallurgical and can be achieved by welding the two together or with explosion techniques (whereas lined pipes feature a mechanical bonding of different materials).

Pipe cladding is used to enhance the durability and the resistance to corrosion of a pipe while keeping its final costs at acceptable levels. Of course, clad pipes are more expensive than lined pipes, as the overlay materials used are, generally, noble metals.

Clad pipe

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