Polyurea elastomer

The main use of polyurea is for waterproofing; it is applied to the walls of tanks, their outer surfaces, or the lower surface of the tank bottom. However, polyurea is likely to be expensive. After application, its surface is not smooth, which affects its aesthetic appearance. Moreover, polyurea has poor compatibility with other types of coatings – in other words, once polyurea is used, no other coatings can be applied on top of or beneath it. As a result, its range of applications is limited. Currently, polyurea is mainly used for waterproofing in buildings, such as in structures made of concrete. Polyurea can bond well with concrete. The above are merely my personal opinions, based on information found on forums; they are somewhat speculative and provided for reference only

There are already precedents in China for the use of polyurea on tank surfaces, whether on the external or internal sides. One of the earliest applications was for anti-corrosion treatment on the outer walls of storage tanks at a certain alkali plant; that was almost 8 or 9 years ago. It’s unclear what the actual results are now. There are also precedents for using this material on the internal surfaces of storage tanks at a thermal power plant, and that was around 5 or 6 years ago. Facts speak louder than words; it is recommended that the person asking this question contact the companies and experts in China who were among the first to develop this product, so as to conduct an on-site inspection. After all, there is a difference between just a few samples tested in the laboratory and the aging process under real-world conditions.

There are already precedents for using polyurea on tank bodies, in areas such as salt water tanks in power plants. In China, the Oceanic Chemical Engineering Research Institute should be at the forefront in terms of construction equipment and technology; the original poster can go there for inspections and consultations.

I am abroad; I am the chairperson of NACE’s Polyurethane Technical Committee. I am also a NACE-certified CIP coating inspector and instructor. I helped establish in my home country the SYT-4105 and 4106 standards for solvent-free polyurethane coatings on storage tanks and pipelines. I was specially invited by the editors of the American magazine Coating World to publish a comprehensive article on polyurea elastomers and polyurethane coating technologies. Here are some views from the international anti-corrosion community regarding the use of polyurea elastomers and polyurethane coatings: 1) To date, polyurea elastomers have been primarily used abroad for waterproofing and wear resistance applications on floors; however, their long-term anti-corrosion performance is poor, which is why they have not been widely adopted for heavy-duty anti-corrosion purposes in the marine, pipeline, and tank industries. In the foreign pipeline and storage tank industry, epoxy resins and rigid polyurethanes (rigid polyurethanes are not the polyurethane elastomers used in China) are still the main materials used for heavy-duty anti-corrosion coatings. The U.S. Navy conducted a thorough evaluation of the corrosion-resistant properties of polyurea elastomers and decided not to use them for the corrosion protection of naval vessels. 2) The application of domestic polyurea elastomers in heavy-duty anti-corrosion applications, such as anti-corrosion coatings for pipes and storage tanks, has been misled by some promotional efforts. In a book written by the so-called “father of Chinese polyurea elastomers,” the example photos showing the use of polyurea elastomers in anti-corrosion coatings for storage tanks are actually stolen from photos of the use of foreign rigid polyurethane coatings, and have nothing to do with polyurea elastomers. 3) To date, there are no official international technical standards for the use of polyurea elastomers in heavy corrosion protection applications in the marine, pipeline, and storage tank industries abroad, which indicates to some extent that the corrosion protection community overseas does not recognize the long-term corrosion resistance of polyurea elastomers.

Our company has carried out projects using polyurea in desalination water tanks and concentrated water tanks; some of these applications have been in use for three years without any problems, while others have shown signs of failure after just one year. In my opinion, the quality of construction is crucial. Moreover, there are no established industry standards for inspecting the application of polyurea for corrosion protection on site, so it relies on the construction teams to ensure proper execution.

Polyurea elastomers can be considered a mixture, and their properties vary depending on the additives used in them. In the waterproofing work for the Beijing-Shanghai High-Speed Railway that I am working on currently, the polyurea used is prone to oxidation; it changes color when exposed to air. Therefore, an epoxy coating is applied after spraying polyurea to prevent air from coming into contact with it. Thus, I believe that polyurea is not suitable for applications requiring high levels of corrosion resistance

The inner walls of the water storage tanks at CNOOC Huiyan Desalination Station are all made of polyurea; it was a project from last year

The desalination water tank in power plants uses spray polyurea technology. Over the past 8 years, our company has carried out anti-corrosion treatment on the inner walls of more than 300 tanks. Indeed, there are many things to keep in mind. To give a simple example: when the sun comes up in the morning, the temperature inside the tank gradually rises, and if the 3-degree dew point difference is not taken into account, water vapor will accumulate on the inner walls of the tank. Although this is a problem that applies to any type of coating, it is particularly important for polyurea, as the temperature after polyurea is sprayed usually reaches around 80 degrees. The heater in the spraying machine and the heating systems in the pipelines are set at around 60 degrees. Coupled with the heat released during the reaction, such high temperatures can cause bubbling issues as soon as the coating is applied to steel surfaces that have condensation or water droplets on them. In other words, polyurea can definitely be used, but without appropriate quality control measures, and without sufficient experience in working inside the tank, the likelihood of problems is very high. Our company has repaired many cases of polyurea anti-corrosion failures. Please contact me for details. Our price is 45 yuan per kilogram (including spraying). Please contact me for the specific details.