64-inch pipes coated with Corro-Coat EP F 1003HW by Arabian Pipe Coating Company of Saudi Arabia.
FBE plays key role in protecting pipes
01 August 2002
Powder coatings have played a part in the protection of pipelines for almost 40 years and are being further enhanced to ensure that they will continue to play an important role in pipeline protection long into the future, says DENIS GRIMSHAW, technical director for Functional Powder Coatings, Jotun Powder Coatings.
In the 1960s, the US pioneered the technology of fusion-bonded epoxy (FBE) which gave rise to a generation of pipeline protection systems, focusing on the excellent anti-corrosion properties of FBE and their tolerance to active cathodic protection systems.
The application of a thin film (350-600 micron) provided an excellent anticorrosion coating for the alkali conditions obtained from cathodically protected pipelines. The limitations of the system include relatively low mechanical resistance which can cause an increase in handling and laying costs for the pipeline during installation.
Some areas of Europe adopted this type of coating as the primary anticorrosion coating - notably British Gas in the UK which developed world-class specifications for FBE. Over the years the expertise in formulating FBE, greater understanding of the application methods and better controls have resulted in much better performance from these systems.
More recently FBE-based coatings have undergone developments to improve mechanical resistance through the use of additional layers of modified FBE, liquid polyurethane or thermoplastic outercoats.
European technology
Also in the 1960s, the Europeans adopted technology based on isolating the pipe from its environment through the use of a polyethylene (PE) coating. Over the years, this has developed from the initial sinter coat systems, which showed poor adhesion, through soft adhesive and hard adhesive two-layer systems.
Eventually, liquid epoxy-primed three-layer systems were developed which led to the real breakthrough with the introduction of powder epoxy primers in the 1980s. These gave economic, environmental and performance advantages and converted most of the market to what is known as three-layer PE coatings consisting of thin (60-120 micron) fusion-bonded epoxy, adhesive and polyethylene topcoat.
More recently, the thickness of the epoxy has increased in appreciation that better performance can be obtained with 200+ microns of epoxy. This increase in epoxy thickness and the American trend for additional protection on the FBE shows a coming together of the North American and European view to enhance mechanical and anticorrosion properties of the protection system through multi-layered complex coatings involving a variety of materials and application methods.
Unique coating application
Pipeline protection is perhaps a unique coating application in which competing technologies, from plastic through powder to liquids applied by methods from extrusion through to spray and even flame spray methods actually work together to achieve the best end results.
Pipeline protection, particularly in the oil and gas sectors, has a high safety requirement as the failure of a highly flammable gas pipeline in an urban area could have catastrophic consequences.
But as the search for oil and gas takes the industry to more remote areas, deeper water, deeper wells and contaminated oils, the demands for protection of the transport system are increasing all the time.
These give rise to the problems of today that require solutions for tomorrow, with a history to guarantee success!
An ever-more competitive world drives the technologies for new solutions to reduce total lifetime costs but without loss of confidence. A potential example of this is the use of powder/powder or powder/liquid systems. They improve the mechanical properties of FBE which may yield a lower material cost than three-layer polyethylene and/or reduce the lay costs compared to standard FBE while having a proven track record of FBE as an anticorrosion coating.
Where pipelines are being asked to operate in new environments such as high temperature, under insulation or in deep water then the failure modes to be expected may not be understood or even known.
Traditional methods such as evaluating loss of adhesion under cathodic protection or the formation of blisters may not be relevant to a coating held at 130 deg C when water may not be present and cathodic protection is unlikely to be effective. New methods of predicting the life expectancy of the pipeline protection system need to be adopted.
Electrochemical impedance spectroscopy is one such tool which is gaining popularity. The traditional anticorrosion aspects of coating are also being supplemented and even replaced by the additional demands of a coating system for insulation/mechanical protection etc.
The new challenges are creating an atmosphere for innovation that has not existed in pipeline coating for 40 years, producing potential solutions at an ever-increasing rate.
Optimised design
The array of innovative solutions gives opportunities for the pipeline engineer to optimise his design both functionally and economically. In order to do this, he is required to understand the local requirements for protection/performance along the entire length of the pipeline.
Rather than using the same coating system throughout the line, projects will depend on utilising different coating solutions and active protection systems in different areas to satisfy a local requirement in the most economical manner - for example, high temperature coatings after the compressor stations, insulated lines to maintain minimum temperatures in critical zones, mechanical protection in rough terrain, high electrical insulation coating in area of stray current etc.
This changing emphasis in design will lead to a need for standardisation not only of the coating systems but for categorising the end-use environment criteria which establishes the evaluation methods for the environment/operating condition independent of the coating system solution.
Internal coating of pipelines for improved efficiency of the product flow or for anticorrosion purposes is a mostly untouched market for powder coatings but with improvements in application methods and the need for faster coating operations, powder solutions for this area will increase.
New powder products for use in the pipeline industry over the last few years include:
Rapid changes
In conclusion, the pipeline industry which brings together a wide range of coating technologies ranging from plastics extrusion to conventional paint, is undergoing rapid changes through the demands of new situations, which is and will continue to challenge all the support industries for solutions. Powder coatings will be amongst the most innovative in offering solutions.
Jotun Powder Coatings
Since its inception in Larvik, Norway in 1968, the Jotun Powder Coatings group of companies now includes powder coatings production units in the Far East (Malaysia, Indonesia, Thailand), Middle East (Saudi Arabia, UAE, Turkey), Europe (UK, Norway, Czech Republic) and the US.
In addition, its technology is licensed to other powder manufacturers in various countries. A recent development in North America - a joint venture with HB Fuller - is a further demonstration of Jotun's commitments to a programme of global expansion.
New production facilities in Pakistan and Vietnam will soon come on stream to increase its global presence. Jotun's factories and laboratories are strategically located, providing close co-operation, fast technical support and excellent logistics - Jotun Powder Coatings is the only FBE coating manufacturer which can make this claim. Its pipe coating division is a dedicated business unit with its own marketing, technical support and product development facilities.
As part of the Jotun A/S multinational coatings company, still owned by the founding Gleditsch family, the powder business is supported by a paints and a cathodic protection division. All divisions focus heavily on providing solutions to corrosion problems in varied environments.
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