The reason of chemical equipment from corrosion

With the development of economy, the increasing demand of chemical equipment, more and more the operation of the production equipment is beyond design ability, thus for global chemical enterprise at present, to prevent the corrosion of process equipment for the loss by the failure has become an urgent problem.Many experts agree that material protection and corrosion protection measures is to reduce maintenance costs and make the important guarantee of the safe and stable operation of the factory.In recent years, the chemical engineering construction in the field of competition, in order to reduce the bid price, the bid for the anti-corrosion measures, the use of high quality alloy, surface treatment technology, such as antiseptic coating (including)Titaniumcn
, cathodic protection and on-line corrosion monitoring system such as the importance of clear enough, this behaves particularly outstandingly in the developing world.The chemical industry for new and existing industrial artifacts protection and protection of the demand is higher and higher, people demand for coating and anticorrosion technology is growing rapidly.Corrosion damage everywhere, corrosion accidents occurred frequently, which in addition to corrosion itself has a spontaneous nature, largely because of corrosion harm to estimate shortage, not deep understanding of the importance of corrosion protection, the corrosion and protection they have no knowledge of science, no corrosion protection measures are taken, or improper anti-corrosion measures.The cause of the corrosion damage
(1) there are many in the chemical production has a certain corrosive medium, such as acid, alkali, salt, water, oxygen, and so on, this is one of the principal causes of corrosion.
(2) the operation of overtemperature and overpressure, chemical equipment management is not perfect, thought not value, and the corrosion is the main production
One of the reasons.
(3) chemical equipment equipment structure design is unreasonable, improper material selection, manufacturing process quality, welding residual, lack of anti-corrosion measures or inferior construction quality etc, provides the corrosive environment.The intrinsic factors of corrosion damage
(1) different metal for different media have different ability to resist corrosion.
(2) the metal of the coarse grains, the faster the corrosion.On the other hand, is slower, such as stainless steel is higher than the corrosion resistance of cast iron.
(3) the surface of the parts more rough, more prone to corrosion.The surface of oxide film is corrosion resistant.
(4) the shape of the equipment structure mutation place, such as openings, gaps, or corner position, rapid metal corrosion.
Corrosion damage caused by external factors
(1) the types of media,
Chemical composition, concentration, pH value, impurities, moisture and oxygen scene is the external cause of corrosion.
(2) the higher the temperature of the medium, the higher the pressure, the faster the corrosion, because corrosion is a kind of chemical reaction, every rise 10%, the corrosion speed increase
1 ~ 3 times _l J.Diffusion velocity increases as the temperature increases, and electrolyte resistance of corrosion, so quicken the reaction of corrosion cell.
(3) medium flow, the faster the more easy to corrosion, it will scour protection film, produced vortex, turbulence, cavitation and cause severe
The impact of the heavy wear and cavitation corrosion.
(4) components by external force or the greater the residual stress, the faster the corrosion.
(5) the influence of the stress and fatigue.Equipment stress produces on the one hand, is formed in the process of machining, such as cold working
Stress and organization stress of hot working;On the other hand in the work can also be under pressure or rotating parts of produce should be
Force.The results of the stress the role of causing distortion of the inner metal, reducing the area of the electrode potential, increase micro batteries
Corrosion.Anticorrosive technology of dalian petrochemical company since 1958 since the earliest using modified phenolic epoxy coating anticorrosive, anti-corrosion technology in me
The chemical industry has gained rapid development.The present anti-corrosion technology mainly include: development of corrosion resistant material, the surface corrosion protection technology, corrosion technology, electrochemical protection and so on.