Carl Allison explains how next-generation coatings can meet the challenges of the oil and gas industry
The extreme conditions and harsh environments associated with petrochemical plants and equipment mean that protection from factors such as corrosion (especially in salt water environments), heat, ultraviolet light, harsh chemicals and wear is essential.
Many items, such as fasteners, valves, seals, gaskets, risers, and fittings, require professional coatings, widely known as PTFE (polytetrafluoroethylene). Essentially, these high-performance coatings combine two plastics—fluoropolymers (the lowest coefficient of friction of any known solid) and high-temperature organic polymers. Together, they provide products with highly versatile characteristics, including improved corrosion resistance, reduced torque, and elimination of wear (damage caused by two surfaces sliding against each other).
Most parts and machinery operating under pressure require some form of dry lubrication. Whether it is low contact pressure applications (such as bearings and actuators) or extreme loads (such as valve springs, seal rings, and downhole tools), professional coating systems have been proven to extend component life and improve performance.
An additional benefit is that the PTFE coating is available in a variety of colors to help identify the product.
Professional coating systems also play a vital role in mold production, providing a wide range of mold release coatings to cover most molding applications. In addition to applying coatings on new molds, you can also remove old coatings, prepare and recoat old molds—thus extending the life of the mold. The advantage of the release coating used for this application is that it eliminates other manually applied release agents (such as spraying and brushing) and generally improves process efficiency.
Other applications require certain pipes or pipe fittings and components used in petroleum exploration to be immersed or coated in thermoplastic materials. In this environment, the advantage of thermoplastic solutions is that the coating has excellent corrosion resistance, chemical resistance, flame retardancy and low smoke and low smoke characteristics. The unique properties of thermoplastic materials provide manufacturers with the opportunity to use coating materials in subsequent operations. There are several applications where the applied coating is reheated during the production process, and adhesives are used to securely attach other materials and components to the original coated item. This is especially common for filters and membranes.
Plastic Coatings Limited uses many PTFE products specially designed for the petrochemical industry, and these products have a good record of success in this field. These roughly cover three main categories: extreme performance coatings; lubricating and mold release coatings; and wear and chemical resistant coatings.
Extreme performance coatings are already very mature in the industrial coatings market. Although these products are lubricants in nature, a wide range of additional features make them ideal for applications in chemical and corrosive environments, high temperatures, or where components may be subjected to heavy loads.
By changing the chemical composition, manufacturers have been able to develop economical solutions to accommodate a wide range of applications ranging from PTFE lubrication and FEP (fluorinated ethylene propylene) lubrication to molybdenum disulfide applications requiring low friction and high pressure applications.
In order to meet the common challenges faced by most of the equipment in the field, the scientists have combined the advantages of two high-efficiency polymers; polyphenylene sulfide (PPS) and PTFE. PPS provides chemical resistance at high temperatures, excellent adhesion and abrasion resistance, while PTFE has non-wetting properties and broad chemical resistance. Together, they can form coatings that are resistant to most acids and alkalis, and are almost completely immune to solvents up to 205°C.
Developed to extend the life of large fasteners and related equipment, these tough coatings-some of which are called "barrier" coatings-protect components from chemical and mechanical damage. Key features include good salt spray resistance, excellent acid rain resistance, and protection from chemical exposure when high pH is a factor.
Static electricity is also a common challenge in the oil and gas industry, and heavy-duty coatings have been specially developed to solve this problem by modifying the basic formula. Therefore, it is now possible to protect the components in a way that helps dissipate static electricity.
Other heavy-duty variants can be used to reduce friction, increase tightening torque, and lubricate parts that need to operate under extreme pressure. For example, Xylan 1425 can provide long-lasting lubrication to the bearing surface and can withstand pressures up to 150,000 psi. Although traditional "molybdenum" grease tends to be washed away, this water-based/VOC compatible product combines PTFE and MoS2 to create a dual lubrication system.
All in all, there is a product that can meet almost all types of components that require protection or lubrication, and the coating industry is constantly developing new solutions to meet the changing needs of the petrochemical industry.
Carl Allison is General Manager of Plastic Coatings Ltd-Commercial
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