Heavy-duty asset protection with industrial pipe coating
The oil and gas industry contributes over $2.5 billion to the New Zealand economy. New Zealand’s gas transmission network is made up of five systems, comprising more than 3,400km of high pressure gas pipeline. There are also pipelines carrying oil, refined products and water from sources to delivery points across the nation. These pipelines traverse land and sea, encountering offshore environments, underground environments, undersea environments, and factory environments at the operation base. Each of these environments poses its own problems, and industrial pipe coating needs to work effectively based on a combination of environment, substrate, and the transport material. A pipeline failure can be disastrous, causing the loss of life, environmental damage, and enormous costs in loss, control, and repair. Pipeline coating works to prevent these failures.
In this article we outline how pipeline coating works, and how to choose a pipe coating and pipe lining based on specific needs. We also look at the companies providing industrial pipe coating services and products in New Zealand.
The benefits provided by pipe coating and lining
Pipelines are protected through the application of both external and internal coating systems. Pipeline coating and tank coating face similar challenges as they need to protect their contents/environment and their substrates from one another. These industrial pipe coating and lining systems serve several purposes, combining various properties to provide the most comprehensive and effective system of protection. These properties include:
- Abrasion/wear resistance
The products that are transported through pipelines are not all refined. Many of the fluids contain particulates which, at high speed and pressure, become highly corrosive projectiles which cause wear and abrasion to the pipe. External abrasion is also a risk for failure.
- Thermal insulation
Heat resistance and thermal cycling resistance are important properties when dealing with pipelines. Pipelines run through summer sun and alpine winter. Heat transfer rate and thermal stress need to be kept to a minimum, and the temperature and viscosity of the fluids needs to be maintained.
- Flow enhancement/assurance
Fluid viscosities, friction, and turbulence all affect the flow of products through a pipeline. Flow efficiency is important for keeping pipelines clean and preventing buildup, which in turn reduces energy usage and the number of shutdowns for clean up.
- Corrosion resistance
Corrosion is one of the leading causes of failures in metal substrates, especially pipelines, costing the world economy billions of dollars a year in prevention and repair. Corrosion for pipelines is an external and internal risk. Externally coatings need to be waterproof as well as resistant to chemicals, salt, and corrosive soils. Internally the coatings need to be able to withstand the corrosive and damaging action of the substance being transported.
Industrial pipe coating and pipe lining can be plant- or field-applied and each environment presents its own difficulties and benefits. A plant-applied coating is the most economical and has the highest level of quality control and quality due to the controlled environment. A field-applied coating needs to deal with exposure to wind, cold, dust, and bugs, but has the benefit of reducing handling damage.
Pipeline coating and pipe lining – The 5 main types
The choice of coating depends upon factors such as environment, substrate, use, transportation, and cost. With the range of environments and elements that industrial pipeline painting needs to withstand, it is no surprise that there are a wide variety of coatings to meet these needs. The main pipe coating systems, or the most commonly applied, can be divided into five groups: asphalt enamel, fusion bonded epoxy, polyurethane, three-layer polyethylene, and three-layer polypropylene.
1. Asphalt Enamel
AE coating is based on bitumen and is used for corrosion protection of steel pipes in the oil and gas industry. They have excellent adhesion to steel, are water resistant, have high electrical resistance, and are resistant to acid and alkali soils as well as bacteria and marine organisms.
2. Fusion Bonded Epoxy Coating
Fusion bonded epoxy coating (also FBE coating) is an epoxy-based thermoset powder coating. This coating is applied as a dry powder and baked, and can be used for internal or external surfaces of pipelines. FBE coating has excellent chemical resistance, abrasion and impact resistance, and high adhesion, making it corrosion resistant. Suitable for underwater and soil conditions from -40 to 80°C. Fusion bonded epoxy coating is one of the most popular coatings for new pipes and can be used as a base coat for other coating systems or as a standalone.
3. Polyurethane Coatings
The high mechanical resistance, chemical resistance, flexibility, ability to withstand harsh weather, UV radiation, and high temperatures, and corrosion resistance of polyurethane works very well for pipeline coating. Underwater environments are particularly suited to PU coatings. They are also a top choice for repairs.
4. Three-Layer Polyethylene
The three layers of 3LPE coating system are an epoxy (FBE) primer, an adhesive middle layer, and a high density polyethylene outer layer. 3LPE has excellent chemical resistance, electrical resistance, temperature resistance, resistance to mechanical stress, corrosion resistance, anti-aging properties, flexibility, and good environment protection (no heavy metals). With that list of properties it is clear to see why 3LPE dominates the global market.
5. Three-Layer Polypropylene
3LPP coatings consist of a layer of fusion bonded epoxy coating, a middle layer of copolymer adhesive, and an outer layer of polypropylene. They have excellent adhesion, are resistant to corrosion, high temperatures, mechanical stress, and chemicals. Particularly suited to offshore projects due to its mechanical strength and ability to withstand high abrasion environments.
The fail-safe pipe coating system – cathodic compatibility
The best way to protect a pipeline from coating failure corrosion is to use a supplementary cathodic protection system as well as a coating. Cathodic protection (CP) systems work by converting the metal surface of the pipe into the cathode of an electrochemical cell. This is done in one of two ways: either by driving a current through the pipe (impressed current cathodic protection), or through providing a sacrificial anode. Not all coatings allow the effective functioning of a cathodic protection system.
Coatings that do not disrupt cathodic protection are known as “fail safe” coatings. They allow the electric current to pass through to the substrate, rather than shielding and blocking it. This means that if the coating does disbond, or water seeps between the coating and the substrate, the cathodic protection will work to prevent corrosion at the failure site.The two pipe coating types that allow the use of cathodic protection are fusion bonded epoxy and polyurethane coatings.
Special properties by pipeline coating type
All the pipeline coatings have beneficial properties in common; however, they also have special characteristics which define the coating of choice for different projects. The table below shows which pipe coating possesses which special properties.
|Property||Asphalt Enamel||Fusion Bonded Epoxy||Polyurethane||3LPE||3LPP|
|High Temperature Resistance||✔|
Pipe coating companies and products in New Zealand
With the thousands of kilometres of oil and gas pipeline across New Zealand, not to mention the pipes transporting water and wastewater, it is no surprise that there are many companies operating across the country who cater for industrial pipeline coating needs. Local companies include Altex Coatings, Dulux, Protective Paints, and Resene, while international companies like AkzoNobel (Interpon/International) and PPG Industries also provide coating for the New Zealand market. Sigmaline from PPG, Carboline products from Altex, and the Corroless range from Protective Paints are all pipe coatings available locally.
The importance of choosing the right coating for environment, use, and substrate, and having the application overseen by professionals cannot be overstated. If you would like more information about pipeline coating, or have a project that requires coating, get in touch! Our experts are here to help. The process is simple: Use our “Request a Quote” or contact forms to tell us the relevant details of your project, and we will collaborate with our coating partners to find the best coating solution for your needs.