Pipeline Corrosion Protection

 

The application and maintenance of anticorrosion protection is one of the most important aspects affecting pipe manufacturing, laying and operation of pipelines. The two essential components of pipeline protection are:

Some argue that the latter is more important than the former.
Both are vital to ensuring the long life and operating safety of cross country pipelines.

 coated pipes on the right–of–way
 

For over 55 years, the pipeline coating industry concentrated on field–applied coatings. Long distance pipelines were coated with automatic equipment
Line Travel CPT (Clean, Prime, Tape) machines. For short lengths of pipe, small, hand operated equipment was used. The main advantages of coating on site were cost and speed.

Major progress in development of coating materials and technologies as well
as rising demands of users made plant applied coatings the desired alternative,
as they promised to be cheaper and more reliable in comparison
to field–applied.

Since the quality of coating achieved with plant applied coatings is better
— pipe can be cleaned to a higher standard and the application is not sensitive to weather or terrain conditions — the industry has made the shift to primarily plant applied coatings. They can now be applied at the pipe mill or at coating plants nearer to the right–of–way.

As, semi–stationary plants become more widespread, they allow the end–user and contractor to deliver pre–coated pipe almost damage free, with improved logistics and delivery and in some cases "added value" for in–country application.

   factory–coated pipe;
girth welds protected with
field–installed Canusa sleeves
 As a rule, anticorrosion coatings may be divided into several categories:

Plant Pipe Coating

The most common types of plant–applied coatings are:

  • Epoxy coating — is available in either “thin film” or double layer
  • Three–layer coating
  • Hot Tape coatings — include the use of heat shrink tape
  • Cold Tape coatings
  • Hot Enamel coatings
Yard Pipe Coating

Some of the above coating systems may be applied in a yard environment. Most suitable are:

  • Hot Tape coatings
  • Liquid coatings
  • Cold Tape coating
  • Hot Enamel coatings
Field Pipe Coating (“over–the–ditch”)
  • Cold Tape coatings — various types are available for special conditions such as high–shear resistance
    or high temperature resistance
  • Hot Tape coatings — a line travel only
Field Joint Protection
  • Cold PVC or PE Tape coatings
  • Liquid coatings — these range from coal tar polyurethane to urethane to epoxy
  • Heat Shrink Sleeves — the most widely used form of joint protection available
Coating Rehabilitation
  • Cold Tape coatings
  • Liquid coatings