The development trend of heavy-duty anti-corrosion coatings in pipeline and storage tank engineering

China Paint Online News:
1, foreword
anti-corrosion coatings used in pipes and storage tanks are heavy anti-corrosion type. Heavy anti-corrosion coatings are characterized by thick coatings, excellent performance and long life, adapted to harsh working environments. Heavy anti-corrosion coatings can be recognized and used in a large number of applications, depending first on scientific formulations and, more importantly, on-site construction techniques. Has formed a series of world-class heavy anti-corrosion coatings, and formed a series of formula technical standards, product technical standards, construction specifications, on-site construction inspection standards and other mature technical information.2, heavy anti-corrosion coating judgment method
according to national standards, industry standards, enterprise standards and other requirements, to see if it has speciality. The judgment method is as follows:
2.1 coating thickness is large
the thickness of the general anti-corrosion coating is measured in sm, while heavy anti-corrosion coating is measured in mm. Such as:
2.2 can work in harsh environments
general anti-corrosion coatings often work in the air, while heavy anti-corrosion coatings often work in the long-term direct immersion of corrosive media. For example, the antiseptic layer of buried pipes often works under the immersion of highly corrosive media of groundwater (fresh water or seawater), subsurgen acids, alkalis or salts, and is also eroded by underground anaerobic bacteria and plant roots. Internal corrosion protection in crude oil storage tanks requires work in crude oil containing acidic media and large amounts of water. The above working environment is much worse than that of the general anti-corrosion layer, which is determined by the nature of heavy anti-corrosion work, but also the general anti-corrosion technology can not be achieved.
2.3 coating has a long service life
according to a large number of practical experience and data at home and abroad, the service life of heavy anti-corrosion coatings is generally 15-20 years. For example, the sewage pipeline at bin seven-way-bin two first station, worked for more than 20 years, the coating for modified petroleum asphalt, thickness of 7mm, spark leakage 20000V.
2.4 unique performance
heavy anti-corrosion coating due to the coating thickness, poor working environment, long coating life and so on, decided that its performance characteristics must be unique, otherwise, it is difficult to meet the above requirements. The characteristics of the coating are summarized as follows:
(1) has strong waterproofing ability to work in water for a long time, but also can work under the erosion of
anaerobic bacteria for a long time;
(3) Resistance to cathode peeling, soil corrosion resistance, anaerobic bacteria, plant roots through the head, soil stress corrosion, corrosion resistance to various conductive facilities above and among the ground, such as railways, wires, trams and other stray currents, resistance to the impact of hard debris in the soil corrosion resistance, the coating necessary for the smooth application of cathode protection of electric spark detection performance.
(4) heavy anti-corrosion coatings must have electrical insulation requirements.
(5) test project's unique heavy anti-corrosion coating must be electrical spark leak detection test. For general anti-corrosion coatings, only routine performance tests are performed during performance inspection, such as viscosity, drying performance, adhesion, flexibility, impact strength, water resistance, heat resistance, chemical media resistance, etc.3, commonly used several heavy anti-corrosion coatings
3.1 thick slurry type epoxy heavy anti-corrosion paint
full name "two-part thick slurry type can be coated with self-curing epoxy anti-corrosion paint." Implementation of standard land: Q/SFYF002-2008; Implementation standard ships: GB/T6822-2007. It is a high solid part, the bottom surface of a coating, can also be used as a medium coating or paint, dry film thickness δ≥0.25mm, generally black light. It has good low temperature curing, maximum heat resistance of 120 degrees C dry heat, weather resistance, acid, alkali, salt resistance, wear resistance and so on. For high temperature sewage, clean water and crude oil and a variety of oil storage tanks and pipes anti-corrosion. Such as: bin two first station discharge station 140m3 discharge tank bottom plate outside the wall, underground non-insulation pipeline outside the wall, etc. are using this coating.
3.2 glass scale coating
which is called glass scale because it is like fish scales. It is composed of glass flakes and main film, these glass scales overlap each other, forming a corrosive external media has a strong deterrent effect of the dense coating, thus achieving a strong corrosion effect.
it has excellent media permeability, good wear resistance, impact resistance, excellent resistance to acid, alkali, salt, oil field sewage and other chemical properties. Good bonding with the substitut, small coefficient of thermal expansion, good temperature fusion resistance, maximum resistance to 150 degrees C dry heat. Widely used in oil storage tanks, sewage tanks, pipe corrosion protection, storage tanks and other steel structures of anti-corrosion protection. Implementation of standard land: Q/SFYF004-2008; Implementation standard ships: GB/T6748-2008. I plant more than 114 sets of trunk lines are using glass scale internal defense.
3.3 high temperature phenol full epoxy paint
full name "two-part thick slurry type can be coated with self-curing phenolic epoxy anti-corrosion paint." It has a high solid content, good low temperature curing (high pressure airless spray is recommended), weather resistance, acid, alkali, solubility, excellent waterproof, salt resistance, up to 140 degrees C dry heat. For high temperature sewage, clean water and crude oil and a variety of oil storage tanks and pipes corrosion protection, can be used for pipeline re-filling once film. Widely used in oil storage tanks, sewage tanks, pipelines, pipelines, cabins and other steel structures, concrete structure protection.
3.4 Solvent-free epoxy conductive electrostitive heavy anti-corrosion coating
which is a new type of heavy anti-corrosion coating that can prevent the accumulation of static electricity and prevent corrosion. It has high hardness and wear resistance, excellent adhesion, good impact resistance and cathode-resistant peeling, thick coating, fast curing, excellent dredging static charge performance. No solvent volatility, no environmental hazards. Up to 120 degrees C heat resistance.
the study of this coating is based on the tragic lessons of lightning strikes at the Huangdao oil depot and the corrosion of static electricity on the tank walls and bottoms. Crude oil, like various solvents, is extremely prone to static electricity during storage and transportation and accumulates in oil, indicating that it is prone to explosion and fire when struck by lightning. When the tank material is non-metallic or the tank material is metal, but the corrosion-resistant material inside it is insulated material, the accumulated static electricity can not be delivered in time, a lightning strike will easily cause an explosion and fire accident. Only by adopting advanced technology to guide static electricity away effectively can this kind of accident be avoided.
the coating is a semiconductor material that conducts electricity and is resistant to corrosion. Therefore, the technical requirements are strict and demanding, for crude oil and a variety of flammable and explosive substances storage tanks, is undoubtedly an ideal anti-corrosion material. It is widely used in oil system oil storage tank wall corrosion protection, chemical plants of various tanks, gas company storage tanks and other internal corrosion. Such as: bin two first station discharge station tank inner wall and inner attachment outer wall using this coating 4 channels, gray.4, the construction of heavy anti-corrosion coatings in pipelines and storage tanks
4.1 coating matching
heavy anti-corrosion coatings and other coatings also exist with the same complementary problems, summarized as follows:
(1) oil asphalt coating re-wounds and overhauls, can use petroleum asphalt (oil asphalt thermal construction), can also be used polyurethane petroleum asphalt cold paint (normal temperature construction), but cut not available glass scale coating and epoxy coal asphalt;
(2) glass scale layer to repair and overhaul, but also with glass scale coating (normal temperature construction), not available petroleum asphalt and polyurethane cold paint;
(3) anti-static coating re-injury and overhaul, anti-static coating (temperature construction) can be used to ensure good conductivity and stability of the coating, not available petroleum asphalt and polyurethane coating repair.
(4) Any new tank corrosion protection can be selected anti-static paint, glass scale coating, phenolic epoxy paint, thick slurry epoxy heavy anti-corrosion coating of any one.
(5) any new pipe can be selected from any of the glass scale coatings, phenolic epoxy paints, thick slurry epoxy heavy anti-corrosion coatings.
4.2 Construction Note
(1) Surface treatment: New steel surfaces should be blasted to ISO standard Sa2.5 or power tools rust removal St3. The surface coated with workshop primer should be dry, clean and free of dirt, and the secondary rust removal at the paint film damage and rust will reach Sa2.5 or St3. Welds and burn-out sites are treated to Sa2.5 or St3 levels. When exposed to atmospheric conditions, the base temperature of the substrate is 5 degrees C up to 40 degrees C and higher than the dew point of 3 degrees C, the relative humidity < 85%. Construction is strictly prohibited in fog, rain, snow and windy weather;
(2) clean surfaces treated in accordance with the above-mentioned methods must be applied within a short period of time after treatment, the general time shall not exceed 8 hours; and
(3) coating shall be carried out in an appropriate manner to detect whether the pre-coating skin, such as forking or scratching, if the skin removes the aging coating, the surface must be free of grease, oil and other pollutants. After the coating is completely dry, the coating appearance, thickness, adhesion, spark leakage detection and other items of inspection, non-conforming must be re-coated until qualified.
(4) Safety: First of all, we should follow the "safety first, prevention first, comprehensive management" of the national security production policy and related safety regulations, adhere to the HSE (health, safety, environment) concept. Before using the product must be training and learning of construction personnel, use should pay attention to safety matters, avoid inhaling solvent vapor or paint, swallowing, skin contact, etc. ; 5. Conclusion
Heavy anti-corrosion coatings are widely used in pipelines, storage tanks and various metal components in heavy industries such as petroleum, chemical, refining, gas, municipal construction and water conservancy. It can effectively reduce the corrosion of various media and environment on tanks and pipes, extend the service life, and low cost, good air dryness, convenient construction, to reduce environmental pollution, save investment plays a significant economic and social benefits.
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