Advances in the research of electrostring coatings in oil tanks.

Abstract: The oil tank conductive electrostitive coating is designed to prevent static fire and explosion accident in the tank, because the oil tank material is steel plate, the conductive electrostitive coating in addition to conductivity also needs to be both anti-corrosion.
the classification, relevant standards, research status and future development direction of the oil tank conductive electrostectrical coating.
introduction is . Liquid petroleum products in the flow, filtration, mixing, mixing, filling, pumping and other conditions, will be due to friction and generate static charge velocity is greater than its export speed, will form a build-up of static charge .
voltage is constantly rising and discharged at the tip, static fire or explosion can occur at any time when the accumulated electrostational discharge energy is within the explosive limits of the mixture of fuel vapor and air.
oil is generally pumped through the pipeline into a variety of storage tanks, this transmission process will produce static electricity, but because the pipeline is full of oil, not enough air, do not have explosive conditions.
oil that has accumulated static charge enters the tank, and if static electricity is not exported in time, the upper air of the tank and the oil vapor form an explosive mixture of gases, which can easily cause accidents.
Therefore, in recent years, electrostectrectectectrelectrelectrelectrelectrelectrelectrative coatings have been paid much attention to, has become one of the anti-static measures of oil tanks, and has been vigorously promoted, the performance and use of electrostectrectrectrectrative coatings in the country has also developed a number of standards and norms.
However, to solve the problem of conductive static electricity but bring corrosion perforation problem, therefore, research and development personnel in the conductive electrostectrical coating research at the same time, has begun to pay attention to the anti-corrosion properties of products, the current application of products both conductive and anti-corrosion, and the future conductive electrostation coatings need to have multi-functional.
1, conductive electrostectrical coating overview
1.1 classification
oil tank conductive electrostitive coating is divided into two categories of added type and the characteristic type, which add type is also known as dispersion type or doping type, the base resin does not conduct electricity, need to add conductive material, and the characteristic conductive electrostectant coating base resin itself conduction, do not need to add conductive material.Added conductive electrostectric coating according to the type of conductive filler is divided into metal system (silver, copper, nickel and other metal powder), carbon system (graphite, carbon black, etc.), metal oxide system (tin oxide, zinc oxide, zirconium oxide and other treatment of mica powder, titanium dioxide powder, sulphate, etc.).
metal conductive coatings are expensive, oxidizing and precipitation-prone, mainly with zinc powder and aluminum powder as conductive materials, but zinc powder affects the octane value of aviation kerosene and is prohibited from being used in aviation kerosene tanks.
carbon-based conductive coatings have low prices and good conductivity, but the migration of graphite is prone to oil pollution, and has been gradually replaced by metal oxides conductive coatings.
, zinc oxide crystals need to be used as conductive fillers alone because of their high resistivity;
conductive mica powder has the advantages of high conductivity, low density and low price, so the selection of conductive mica powder as the main conductive filler is the main means of the current development of conductive electrostation coatings.-type conductive electrostectronic coatings use conductive polymers as substitut resins with large π electronic systems such as polyphenylamine (PAN), polyacetylene (PA), polyphenyl thioether (PPS), polyphenyl ether (polyphenyl ether) PP), polythene (PT), polyphenyls (PQ), polyphenyl acetylene (PPV), poly1,6-diphenyls (PHF), polythionine (PTIN) and so on, with polyphenylamine research and application the most.
-type conductive electrostitive coating is very limited due to the complexity and high cost of conductive resin production process. The performance of the added and characteristic conductive electrostectrecture coatings is compared to Table 1.
1.2 Performance and Standards
In order to prevent static fire and explosion accidents, the State has promulgated a number of standards and technical specifications to limit the performance of electrostectrectrometer coatings, the main standard specifications as shown in Table 2. among them, GB/T 6950-2010 "Light oil safety electrostectrective conductivity" Appendix D "Petroleum conductive electrostectural coating technical indicators" and GB16906-1997 "oil tank conductive electrostectrective coating resistivity determination method The revised standard raises the limit for surface resistivity to 108 to 1011 s, which is still very different from the 105 to 109 s specified in the U.S. standard DODHDBK-263.
108 to 1011 s covers the physics-defined insulator resistivity of 1010 to 1011 s, which may be due to corrosion protection, but this indicator is debatable.
although the standard has been developed a lot, conductive electrostectrical coatings pay attention to the conductive electrostectrical performance but neglect the anti-corrosion performance, therefore, the tank avoided fire explosion accidents, but frequently corrosion perforated oil leakage phenomenon.
Yanfeng tested a crude oil tank and found that the total area of corrosion of the bottom plate of the tank amounted to 23.6m2. Of the 1,729 detection points, 1,229 are corrosion points with a corrosion ratio of 71%, of which 32 are corrosion perforated.
According to a survey report on the anti-rust effect of new oil depots since 1994, the vast majority of new storage tanks in Six oil depots in Zhoushan, Hangzhou, Wenzhou, Lushan and Shanghai in Zhejiang Province have been severely corroded after coating, and 2 cases have been severely corroded to the bottom of the tank perforated oil leakage.
Therefore, the tank anti-static coating and other industries on the requirements of anti-static paint is different, in addition to meeting the resistivity standards, but also to meet the anti-corrosion and oil resistance:
first, the object of coating is steel structure, so in addition to anti-static function must have excellent anti-rust resistance to steel, the requirements of media penetration period of more than 7 a;
second, must be resistant to long-term immersion of petroleum products, and do not pollute the oil or induce product quality.
2, conductive electrostectrical coating research status quo
2.1 carbon-based conductive electrostectrical coating
carbon black electrode inductance is much higher than the electrode electrode level of iron, and the coating anti-permeability is poor, the coating of carbon-conducting electrostectantic coating will cause accelerated corrosion of iron, and carbon migration will cause oil pollution.
But its price is low, some oil tanks as intermediate paint, the formation of zinc-rich primer and carbon-based electrostitive paint and non-carbon-based electrostitive paint supporting system, or has a certain economic rationality. The research of carbon conductive fillers mainly includes the following aspects:
(1) using even heat treatment,
chemical thing method to treat the carbon surface, improve conductivity; Zhang Lulu et al. modified the traditional solvent-free epoxy glass scale coating with homemade chemical silver-plated scale graphite, which not only improved the conductivity, but also improved corrosion resistance.
Shiyu and others used carbon-based conductive fillers to develop a paint phenol conductive electrostation anti-corrosion coating, with outstanding comprehensive anti-corrosion and electrostitive conductivity, for the petrochemical industry to provide a more ideal conductive electrostation anti-corrosion coating. In recent years, a new type of carbon-based electrostectrectectrosive coating has emerged, that is, carbon nanotube conductive electrostectrecture coating, adding a small amount of carbon nanotubes can obtain good conductive performance, which is convenient to improve other performance, such as improving the carbon-based electrostectrectecture coating corrosion performance is poor, dark color problems.
Zhao Fujun and others on the surface of carbon nanotube acid treatment, and then by the coupled agent surface change and ultrasonic dispersion, carbon nanotubes can not only be more evenly dispersed in the coating, but also carbon nanotube surface also has more polar groups, can reduce the resistivity of conductive coatings, improve the surface properties of the coating.
2.2 Non-carbon conductive electrostation coatings
added conductive electrostation coatings in addition to carbon-based conductive electrostation coatings, the addition of other conductive fillers can be attributed to non-carbon conductive electrostation coatings, because its light color is also known as light-colored electrostation-conducting coatings.
is currently research and development and widely used is the addition of conductive mica powder epoxy conductive electrostectrical coating. Wang Ning et al. to epoxy resin as the base material, conductive mica powder as the conductive system into a light-colored epoxy tank conductive electrostecturic coating.
study found that the main factors affecting the conductive properties of coatings are the proportion of conductive fillers in coatings and the curing time of coatings, and by adjusting the pigment ratio and conductive mica powder dosing can greatly improve the corrosion resistance of coatings.
high wave and others developed into a thick slurry-type light-colored epoxy conductive electrostitive coating, can reduce the number of coating channels, improve efficiency, and explore the conductive mica powder dosage, pigments and additives on the resistance of the impact.
in addition to epoxy conductive electrostectrectant coatings, the research on fluorocarbon conductive electrostectrecturic coatings and polyurethane conductive electrostation coatings has been carried out, and with the deepening of the research, the research direction has gradually shifted to environmentally friendly coatings.
Such as Liu Chenglou and others developed a water-based epoxy conductive electrostectric coating, in addition to environmental characteristics and conductivity, but also has excellent chemical corrosion resistance, oil resistance

In the design of the formula for conductive electrostation coating, a rust converter and a rust stabilizer have been added, and a low surface treatment electrostitive coating can be applied to 2 3,000 m3 reservoirs.
2.3 This type of conductive electrostectrectectral coating
the characteristic type of conductive electrostectrecturic coating to polyphenylamine as the main research direction, in addition, the high conductivity of polycycline, easy to become a membrane, non-toxic characteristics have also become one of the research directions.
high electrical conductivity, good air stability and high thermal stability, but its insoluble, difficult to process molding problems have been bothering people.
researchers at Changchun Institute of Applied Chemistry used the method of "doping agent induction to increase capacity" to dissolve polyphenylamine, which has made a breakthrough in solving the problem of the difficult processing of conductive polymers such as polyphenylamine, and has achieved industrial production. polyphenylamine is added to the coating and is reactively embedded in the molecular structure of the film, so that it is electrostatically conductive and the resin substitin is conductive.
Fu Hai studied the effect of polyphenylamine varieties and dosing on the conductivity of epoxy coatings, and pointed out that when the amount of polyphenylamine doped with xenonyl benzene was 5% of epoxy resin, it had a good electrostectric conductivity, and the addition amount continued to improve the conductivity of electrostectricity.
16% graphite with 5% polyphenylamine was added to the carbon-based electrostectrical coating, and rust resistance and chemical resistance were greatly improved, and graphite migration was overcome.
high synthesis costs increased the production costs of polyphenyl coatings, Liu Yijun and others using oxidation agglytic agglycation legal system prepared inorganic acid doping low-cost, high conductivity of conductive polyphenylamine, and the conductive polyphenylamine as a conductive filler, epoxy resin as a film, the preparation of low-cost, conductivity adjustable conductive coating.
3, the direction of development of electrostectrelectrelectrelectrative . In 2003, China announced the launch of the Petroleum Strategic Reserve Project, with a total investment of more than RMB200 billion (tank coatings account for about 5% of the project's investment, up to RMB10 billion), and the establishment of an oil strategic reserve base equivalent to 90 d crude oil imports, with a total planning of 3 phases, with reserves scheduled for: 14 million t in phase I, 28 million t in phase II and 28 million t in phase III.
preliminary estimates, for every 10,000 m3 tank, the inner wall conductive electrostectrectrecture coating 1.5 t, then a total of 2400 t. In addition, there are oil refineries, provinces and cities to supply oil, storage tanks, conductive electrostectrelectrelectrelectrative coatings demand more than 5,000 t, "12th Five-Year" annual demand of more than 1,000 t.
The above data show that the market demand for conductive electrostectrical coatings is huge, the application of conductive electrostectrical coatings in built tanks will provide experience accumulation and technical support for the oil tanks under construction and to be built, and for the future conductive electrostectrical coatings point out the direction of development: . First, because of the particularity of the application environment (the tank is a large-scale device, construction, maintenance, refurbishment is difficult), its development direction is first of all high-performance, requiring the coating with a longer anti-corrosion period, and has easy maintenance, heavy coating performance characteristics. second, the oil tank conductive electrostectrectecture coating demand is large, the cost will become a factor affecting its development, the development of low-cost electrostectrectrectrectrectrecture coating is one of its development direction. Third, due to the enhancement of social environmental awareness, but also from the construction safety considerations, environmentally friendly conductive electrostectrectrectrecture coatings are the future development trend, research in this regard has been carried out, including solvent-free electrostectrectrectrectrecture coatings have been used in some oil tanks.
Fourth, the corrosion caused by the emphasis on conductivity of conductive coatings makes us realize that electrostature coatings should be versatile, that is, they should be both conductive, corrosion-resistant, high and low temperature resistance, fire resistance and so on.
4, Conclusion . As a special functional coating, the oil tank conductive electrostectrectrific coating has been widely used in the petrochemical industry and plays a vital role in the safety of people's life and property.
with the in-depth research and practical application needs, the requirements for the performance of conductive electrostectrecturic coatings are no longer a single pursuit of conductivity, its corrosion resistance, resistance to high and low temperatures will also be required. The research and development of conductive coatings is of long-term significance to China's economic construction and national defense construction.
.