Research On The Problems And Solutions Of Anticorrosion In High Temperature Oil Tank

Due to the change of production process conditions in oil refining,the service temperature of steel-welded oil tank increases,and the increase of storage oil temperature directly leads to the failure of anticorrosive coatings,shortening the service life of coatings,and if the failure of coatings cannot be detected in time,it results in thinning,perforation and leakage of the tank under the corrosive medium in the tank,and even fire,explosion and other accidents.This work investigates the present situation of high temperature failure of anticorrosive coatings for high temperature oil tanks,types of failure,the mechanism of medium corrosion of oil tanks after the failure of coatings,and the anticorrosive methods for high temperature oil tanks in present China.It is concluded that the commonly used epoxy,polyurethane,fluorocarbon and other coatings are defective in dealing with the anticorrosive effect in high temperature oil tanks.The defects of coating and the root causes of failure caused by high temperature are the coating molecular structure,anticorrosion construction process,and operation conditions.This work further explores how to reduce or avoid the impact of these three factors theoretically and practically,and provides a better solution.(1)The influence of coating molecular structure on corrosion resistance of high temperature oil tank is analyzed.From the point of molecular bond energy,it is pointed out that the key factor of temperature resistance is molecular bond energy.It is concluded that the reason why traditional coatings and schemes cannot meet the requirements of high temperature oil storage is the defects in materials structure,and it is necessary to screen the materials which can meet the requirements of high temperature resistance and resistant to oil and electrostatic as well as economical and practical to be used as new anti-corrosion coatings for high-temperature oil tanks.Natural urushiol coatings were selected as the research object through investigation and molecular structure analysis.It was found that natural urushiol coatings have a unique molecular structure,can participate in condensation polymerization,oxidative crosslinking and polymerization,and can form stable network structure with a large molecular bond energy.At the same time,it is easier to prepare high performance composite coatings with it.Therefore,a series of experiments have been carried out to verify the physical properties of urushiol coatings.First,the physical properties of urushiol coatings have been tested.The main physical parameters include: color and appearance,viscosity,drying time,flexibility,adhesion,impact resistance,solid content,resistance to hot water bath,conductivity and other technical indicators.The second is to carry out chemical performance tests,which include: salt resistance,acid resistance,alkali resistance,oil resistance,conductivity,resistance to hot water bath performance and other technical indicators.The third is the laboratory high temperature test,using the test block in the electric constant temperature box for heating,from 80℃ to 300℃to verify its heat resistance.Eventually,the urushiol coating was used in the high temperature oil tank on the spot.Two 10000 cubic meters of residual oil tank and distillate oil tank were selected as the test objects.After six months,the tanks were opened for inspection and verification.It is concluded that urushiol coating can be used for internal anticorrosion of high temperature oil tank.The scheme can meet the requirements of long-term use of high temperature oil tank under 180 oC.It provides a guiding scheme for the current anticorrosion of high temperature oil tank.(2)By analyzing the factors influencing the anti-corrosion performance of high-temperature oil tank during construction,the main factors influencing the quality of coating film during construction are found out,such as steel surface treatment,coating mixing,coating spraying process,coating design thickness and maintenance time,etc.At the same time,from the causes and mechanism of these construction factors,the important influence of these factors on the coating life is analyzed,and the importance of how to avoid these factors is discussed.It is proposed that the influencing factors can be overcome and the coating quality can be improved by strengthening the operation process management,and the solutions for each factor are put forward to meet the standards.At the same time,this chapter puts forward the technical requirements of anti-corrosion construction process of oil tank,for the steel surface treatment of oil tank,anti-corrosion acceptance standards,coating product acceptance,construction equipment inspection,construction personnel technical disclosure,anti-corrosion coating ingredients,coating application process,construction site environment requirements,coating quality protection,anti-corrosion completion evaluation,coating maintenance,and other aspects.Based on the above,technical parameters and requirements are put forward.By standardizing construction behavior,high quality coating can be guaranteed to meet the needs of high temperature resistance.(3)By analyzing the influence of operating conditions on the anti-corrosion performance of high-temperature oil tanks,the main factors affecting the operation process at this stage are found out,including: the anti-corrosion coating is soaked in high-temperature hot water,the anti-corrosion coating is corroded by inorganic salts and the medium with high sulfur content,and the anti-corrosion coating is swept by high-temperature steam on the aging process.Other factors include sound,damage during oil tank cleaning machinery operation,etc.This work analyzes the causes and hazards of each influence factor one by one,and puts forward the improvement of production technology,operation,and maintenance,thus reducing corrosive environmental factors in oil tank and external force damage factors on coating corrosion damage,creating a good service environment to help prolong the service life of high temperature oil tank coatings,and provide guidance for industrial production and operation.(4)By studying the existing problems of anticorrosive coatings for high-temperature oil tanks,it is reminded that when the process temperature rises in the daily use of oil tanks,it is necessary to carry out scientific and safety risk assessment on whether the anticorrosive coatings for the original oil tanks can meet the needs of use,and to go through the procedure of process change so as to permit production and ensure safety.