For companies that need to transport water or chemicals across long distances, pipelines are an essential part of the revenue stream. Pipeline coating systems play a critical role in the pipe’s structural integrity, protecting the user’s investment and preventing damage to the surrounding environment.
According to a study backed by the US Federal Highway Commission, metal corrosion costs an estimated $276 billion annually.
A compromised coating will eventually cause the pipe to corrode, weakening the metal and potentially causing a fracture within the pipe.
When that happens, the contents of the pipe — whether it’s water, gas, or other chemicals — may leak into the environment. The materials are then at risk of contamination from rust, dirt, and bacteria, potentially causing millions of dollars in damage.
“You need to be very careful in choosing the right protective coating for your pipelines,” says Shiona Stewart, Industry Marketing Manager for Transportation, Industrial Furniture and Floor Coatings at BASF. “You need to have that resistance to ensure these chemicals don’t degrade the coating over time and ultimately break it down.”
How do you choose the right coating system for your pipeline? It depends on what you’re transporting — whether it’s chemicals, gas or potable water — and where you’re transporting it — whether it’s underground or aboveground.
Resisting corrosion up high and down low
The ideal chemistry for a pipeline’s exterior coating depends on its surrounding environment and exposure to various weather conditions. Aboveground pipelines may require a system that withstands UV exposure, rain, high humidity, or freezing, depending on the climate. Users may also want to choose a high-gloss, pigmented system if they are concerned with the look of their pipes.
Aesthetics, along with protection against external elements like UV rays, will be less of a concern for underground pipelines. Instead they tend to benefit greatly from high abrasion resistance.
“If the pipe is underground, it’s really going to need to be resistant to corrosion,” says Stewart. Corrosion resistance is an important consideration for aboveground pipes as well, but users will also need to account for the UV degradation that occurs outdoors.
To protect the pipe from corrosion, coatings create a physical barrier to prevent the surface metal from coming into contact with water and salt.
“The chemistry of the resin as well as the pigments, additives, and solvents chosen are extremely important,” says Tony Neely, Technical Specialist of Waterborne Coating Technologies at BASF.
For example, two of BASF’s newest products — Joncryl PRO 1524 and Joncryl OH 8314 — use a unique dispersion technology to create a clean water phase. The technology essentially reduces or eliminates the salt, excess surfactant, and hydrophilic oligomers found in most dispersions.
“These types of molecules can attract water to the surface, which can have an adverse effect on the metal pipeline,” Neely explains. He adds that BASF’s waterborne Direct-to-Metal (DTM) technologies allow for a low-VOC system that can be strategically formulated into a coating optimized for corrosion resistance.
In addition to the surrounding environment, pipeline interiors must be able to withstand the types of chemicals they transport, such as petroleum, fuels like oil or natural gas, slurry, or sewage, to name a few examples.
If the system isn’t suited to the chemicals you’re transporting, the coating itself could break down and cause corrosion in the pipeline, ultimately damaging the piping material.
Pipelines can face another challenge when buildup occurs on the inside of the pipe, thereby slowing down the flow of materials through the pipe.
Regular maintenance plays a large role in avoiding costly mishaps, but Stewart advises users to exercise caution in choosing the right protective coating to avoid degrading and compromising the pipe material.
“You have to be very selective as to how you choose the material that the pipe is re-coated with,” she says, “to make sure that it’s compatible with [the previous system] and that it’s going to offer the necessary protection for the pipeline.”
What’s coming down the pipe?
Pipeline coating technology has steadily been advancing with the times. One of the most significant changes, according to Stewart, involves extending the lifespan of the coating itself.
In particular, products developed by BASF will allow applicators to provide superior protection compared to other players in the market — and potentially extend warranties on their coating systems.
“The trend is to really develop the chemistries to have longer-term exposure, giving manufacturers the ability to extend warranties associated with the piping,” she says. “That means mediating the chemical degradation as much as possible to extend the lifetime of that coating on the pipe component.”
Stewart says the potable water space has also been gaining more attention in recent years.
“There has been a focus on moving away from epoxy-based technology due to Bisphenol A leaking out into the water. That, obviously, is not an attractive option to the consumer.”
Bisphenol A or BPA has been classified as an endocrine disruptor, which presents a health concern when ingested.
“We are starting to see more innovation, or more chemistries, being considered as alternatives to epoxy,” says Stewart. In the realm of pipeline coatings, players in the field of epoxy alternatives include polyurethane and acrylic-based technologies. “One of the advantages BASF has in this space is that we do have a broad portfolio of chemistries to offer, depending on what type of material is being transported within the pipes.”
Coatings with built-in cost savings
In addition to the health hazards, Neely says epoxy chemistries also present rising cost issues to manufacturers. Waterborne DTM coatings, like the ones offered by BASF, allow for significant savings in time and costs, as well as reduced VOC emissions.
“[DTM] coatings are intended to be applied after minimal surface preparation with only one application step,” Neely explains, adding that DTM coatings protect against corrosion without the need for active pigments.
Waterborne coatings, for their part, are easy to clean and use solvents that are lower in odor, toxicity and flammability. When compared with traditional solvent-borne coatings, Neely says waterborne coatings “are better for worker health and safety, with less impact on the environment.”
BASF is also developing some unique curing chemistries that aim to accelerate the applicator’s ability to provide a high-film build in one application of the coating, rather than multiple applications.
As a result, Stewart says formulators may be able to expect some labor savings with those technologies.
“The curing technologies that we are developing will enable a formulator to put one film coating down and ultimately have curing done very quickly, so the pipe can be put into service much faster — or it can be repaired and returned to service faster — as a result.”
Advice for formulators and applicators
When it comes to working with pipeline coating systems, Stewart and Sarah O’Boyle, Research Technician for Waterborne Coatings, have a few pieces of advice for manufacturers at the formulation and application stages.
Applicators must be aware of factors like pot-life and choose the optimal viscosity and rheology package for the application method. They should also ensure they have a consistent and robust film that doesn’t allow the material to be penetrated.
“If you don’t apply a very smooth and consistent film, that film could end up being more susceptible to chemical or water penetration,” says Stewart, “which could in turn lead to corrosion damage within the pipe.”
Formulators will need to make sure the coating meshes well with the characteristics of the substrate being coated, as well as the geometry and rheology of the pipe surface.
“Care must be taken when choosing pigments and additives, as there can be a drastic difference in corrosion protection between various formulations,” says O’Boyle.
BASF works with its customers to ensure its products work well with the intended application. It also tests the effectiveness of its formulations, including corrosion and UV protection, at a large weathering center in their facility.
O’Boyle says dispersant, pigments, defoamers, wetting agents, and thickeners are all specifically tested for compatibility with the resin and for corrosion resistance in the coating.
“By spending a significant amount of time developing and optimizing these formulas, BASF coatings can provide the substrate with substantial protection from the environment.”