№1 January 2012Table of contents Issue Archive
№1 January 2012Table of contents Issue Archive
№ 11 (November 2008)
In 1960, an anticorrosive coating method was invented for steel pipes: a fusion bonded epoxy coating or epoxy powder coating named Scotchkote™. A triple-layer coating was introduced and applied in Germany in 1979.
Epoxy powder material Scotchkote™ 206N was applied as the first layer. The invention of Scotchkote™ materials and technology made a breakthrough in the area of steel pipe coating.
Currently epoxy powder materials are applied in the following yard coating systems:
• Fusion Bonded Epoxy (FBE);
• Dual Fusion Bonded Epoxy (DFBE);
• Three Layer Epoxy-Polyethylene (3LPE) or Epoxy-Polypropylene (3LPP), depending on an external layer.
These anticorrosive coatings meet all requirements set in modern specifications for coatings and aslo comply with industry standards of major enterprises.
In Russia, epoxy powder materials were applied mainly as a ground coating or primer in the triple layer polyethylene yard coating system. The application of FBE coatings on pipes as a single anticorrosive coating significantly reduced their subsequent applications due to insufficient impact strength. Normally, the impact strength value of epoxy coatings does not exceed 4-6 J at a test temperature of +20(±5) С and reduces to 2-3 J under subzero temperatures (-20-40 С), which significantly complicates transportation of coated pipes and construction and assembly operations during winter seasons.
Triple layer coatings meet the most stringent requirements, and their application in the Russian market is fully justified and well-proven. However, single layer (FBE) and double layer (DFBE) coatings have a few important advantages and their application in Russia can be technologically feasible and economically sound.
Major advantages of FBE/DFBE coatings include:
• good adhesion to steel both in dry and humid conditions;
• excellent resistance to cathodic sag;
• excellent retention of protective properties at high operating temperatures for a long time.
The Dual Fusion Bonded Epoxy (DFBE) system is distinquished by high impact strength, resistance to cutting, tearing and abrasive wear. By now, DFBE coatings are successfully used for commercial operations in many countries for over ten years. Pipes with these coatings are most widely used in such conditions when transportation of coated pipes is connected with a high risk of coating damage and when stringent requirements are set to mechanical strength.
The first layer of this system is one of standard epoxy powder coatings Scotchkote™ 226N or 226N+ produced by 3М. The coating is a layer of 250-300 µm thick applied on preheated steel surface by an electrostatic spraying method.
The second layer is also an epoxy powder coating Scotchkote™ 8352 or Scotchkote 6352, which is significantly harder and more resistant to mechanical damages. The material is sprayed as a layer of 500-750 µm thick over the first layer to create an external coating with increased impact strength and resistant to puncturing, cutting, abrasive wear, and penetration.
Coatings Scotchkote™ 8352 and Scotchkote™ 6352 have been developed specially to ensure protection of the first layer against mechanical impacts during transportation of coated pipes, directed drilling and pipeline construction in conditions of stony soil. Specially designed composition of Scotchkote™ 8352 coating ensures excellent ductility properties that enable cold bending of pipes without causing damages to the coating integrity during construction and assembly operations, in winter as well.
It is also worth to mention that this external coating type is widely applied in construction of crossovers by the directed drilling method, because dual fusion bonded epoxy coatings are featured by a significant technological advantage, namely by a higher resistance to cutting as compared to three layer coatings.
An important economic benefit of FBE and DFBE coatings is their low cost as compared to 3LPE ones, with a difference reaching 30 percent for FBE and 10-15 percent for DFBE. A process of applying one layer and dual layer coatings require significantly less expenditures as compared to that for three layer coatings. As for requirements set to surface preparations, they are similar for both coating systems. In addition, an application rate for FBE and DFBE is higher than for three layer coating. Taking account of all above mentioned and a lower cost of materials for coating application per 1 sq. meter, the cost of DFBE coatings and the more so of one layer FBE coatings are much less as compared to three layer ones.
Epoxy coatings Scotchkote™ has proven its performance and economic efficiency in many pipeline projects in Russia, including those with pipelines up to several thousand kilometers long. Sakhalin-1 and Sakhalin-2 Projects are good examples and their significance to the Russian oil and gas industry could hardly be overestimated.
In 2002-2004, Volzhsky Pipe Plant fabricated two rather large batches of pipes with diameters of 530×12 mm and 762×12 mm, with dual fusion bonded epoxy coatings Scotchkote™ 226N and Scotchkote™ 6352 produced by 3М. These coatings proved their efficiency during pipe transportation to Sakhalin and during construction and assembly operations in complicated conditions.
In 2008, Vyksunsky Metallurgical Plant fabricated pipes with dual fusion bonded epoxy coatings Scotchkote™ 226N and Scotchkote™ 6352 under the framework of the Odoptu Project (Sakhalin-1).
Thus, taking account of economic efficiency and competitiveness of single layer and double layer epoxy coatings, their application for small and medium size pipes (up to 820 mm) proves to be of higher performance and economically sound.
In addition to production and development of epoxy powder coatings, 3М is active in working over liquid epoxy and polyurethane coatings that can be used for repair of yard coatings and as independent coatings for application both in the workshop and in the field.
Several years ago, Canadian engineers developed liquid polyurethane coating Scotchkote™ 352 that can be applied both in the workshop and in the field and under subzero temperatures. This is a two-component polyurethane anticorrosive coating designated to protect underground and surface metal structures: pipelines, tanks, connecting parts, sliding valves, etc.
Coating Scotchkote™ 352 is applied as one layer without priming; it cures when applied on the pipeline surface even at subzero temperatures and ensures required protective properties. In Canada, this material is approved for application by leading gas-transmission companies, on pipeline surfaces with a temperature up to minus 5-10 С. This property allows operations in winter, which is without doubt especially important for construction conditions in Russia.
Basic advantages of coating Scotchkote™ 352 include good adhesion to steel, high resistance to cathodic sag, and resistance to long-term puncturing, abrasion and cutting. This effect is achieved by adding ceramic microspheres produced by 3М to the material. Rupture resistance for this material is 32 MPa at +20°С. The coating withstands at least 10 thermal cycles from –60 to +20°С. It has been proved by testing in many foreign laboratories and in anticorrosive coating laboratories of VNIIST and VNIIGAZ research institutes.
Coating Scotchkote™ 352 is widely applied in Canada, the USA and Ukraine. In Russia, this material is successfully applied for Gazprom’s facilities. VNIIGAZ research institute approved this coating to be applied as a layer 1.5 mm thick or thicker.
Due to high performance and processing properties coating Scotchkote™ 352 was selected to protect welded joints during construction of pipelines for Sakhalin-1 Project and was applied during construction of the Varandei Oil Terminal in the Barents Sea and a submerged crossing through the Baidaratskaya Bay in the Bovanenkovo-Ukhta gas pipeline project in 2008.
In 2007, 3М acquired E.Wood, a UK company producing anticorrosive coatings with brand names of Thortex, Copon and ThistleBond that proved to be highly efficient and durable coatings in the anticorrosive coating market.
The brand name of Copon has a long and successful history of application for pipeline corrosion protection. At present, there are many materials applied both for pipeline inner lining and external coating.
One of these materials is COPON HYCOTE 162 HB that has been developed as an epoxy inner lining to be applied for pipelines without a solvent; it can also be used as an external protective coating in conditions requiring resistance to abrasion. COPON HYCOTE 162 HB is recommended as a coating for concrete and steel tanks, water outlets, and dike walls, including chemical effect conditions. The coating is resistant to a variety of water soluble chemicals and is suitable for services with crude oil and natural gas with high contents of salts, water, acids and corrosive gases.
COPON HYCOTE 165 coatings are dual component polyurethane coatings for external protection of gas and oil pipelines. These coatings can be applied in the workshop and in the field, for newly constructed pipelines, for repair and renewal operations, and for re-coating of individual pipeline sections. Polyurethane COPON HYCOTE 165 coatings are described by excellent physical, mechanical, protective, and performance properties comparable with fabricated polyethylene pipe coatings, meet the GOST R 51164 requirements, and are suitable for long-term operation of coated pipelines in underground, underwater and marine environment conditions, at temperatures up to +80 С. It is worth noting that this coating is entered into the Transneft’s register and is approved by Gazprom for application on pipe parts in the workshop.
E.Wood was the first company in the world that proposed to use extra-smooth inner lining for gas pipelines and launched production of materials with the brand name of Copon for such application. These materials were used in many significant gas pipeline projects all over the world including the Blue Stream, Sakhalin-2 and other projects. Today, E.Wood produces materials for application of extra-smooth inner lining with dry residue retention of 50 percent, 75 percent and 100 percent. The applied coating is featured by extra-smoothness and allows the reduction of inner pipe wall roughness. This results in reduction of friction losses during transportation and increases pipeline throughput capacity.
Since 3М acquired E.Wood, all coatings bearing the Copon brand name will be produced under the brand name of Scotchkote coatings.
Development of anticorrosive coatings is a priority and a promising branch, with a lot of customers in this sector; these circumstances encouraged 3M to launch its own production in Russia. In September 2008, 3М officially set up its first plant and launched production of epoxy powder materials in Russia. The Russian Federation has become the 33rd country where 3M launched its own production. Since 2006, investments in this industrial complex made over $28 million. In addition to pipeline corrosion protection coatings, the enterprise will also produce personal protective equipment and other products. The industrial complex in Volokalamsk is featured by ultramodern equipment similar to that installed by the company only in three countries of the world. Local production will contribute to availability of materials as well as reduction in their cost and period of delivery to customers. Besides, the company plans increase in output.
A new scientific research laboratory has been built at the base of the Volokalamsk plant, where products can be adapted to comply with Russian standards . This laboratory is also used to provide technical support to 3М customers.