How to prevent and treat common corrosion problems in industrial discharge system

As a key facility in industrial production, the industrial discharge system is responsible for the emission and treatment of pollutants such as wastewater and waste gas. Its operating environment is complex, involving a variety of corrosive media, which poses a severe challenge to the durability of equipment and pipelines. Corrosion problems not only affect the safe and stable operation of the system, but also lead to increased maintenance costs and increased environmental risks.

Main types of corrosion in industrial discharge systems

Chemical corrosion

Chemical corrosion is mainly caused by the direct reaction of acidic or alkaline substances in the emission medium with metal materials. Industrial wastewater often contains strong acids such as sulfuric acid and hydrochloric acid, and waste gas contains corrosive gases such as sulfur dioxide and hydrogen chloride. Long-term contact leads to corrosion and exfoliation of metal surfaces.

Electrochemical corrosion (galvanic corrosion)

When multiple metal materials are mixed, current flows due to potential difference, causing electrochemical corrosion. Galvanic corrosion is easy to form at the joints of pipes and equipment of different materials in industrial discharge systems, accelerating local damage.

Stress corrosion cracking
Under the action of tensile stress, cracks in some metal materials expand in corrosive media, causing equipment rupture and failure. High temperature and chloride ion-containing environments are particularly prone to stress corrosion cracking.

Microbial corrosion
Some industrial wastewater contains corrosive microorganisms, and microbial metabolites such as hydrogen sulfide aggravate metal corrosion. Biofilm adhesion and microbial activity lead to aggravated corrosion inside the pipeline.

Analysis of the environment and mechanism of corrosion formation
Multiple corrosion factors in the industrial discharge system are superimposed. Acidic media and high temperature environment accelerate corrosion reactions. The presence of oxygen promotes the oxidation corrosion process. Changes in flow rate inside the pipeline cause local corrosion points. The accumulation of corrosion products leads to the deterioration of the corrosion environment and the formation of corrosion cells. When the system is unstable, the concentration of the medium fluctuates, resulting in uneven corrosion rates.

Material selection strategy for corrosion prevention and control
Corrosion-resistant alloy materials
Select materials with excellent corrosion resistance such as stainless steel, nickel-based alloys, and titanium alloys to adapt to complex media such as acid, alkali and high temperature. Nickel-based alloys perform well in strong acid environments and extend the life of equipment.
Anti-corrosion coating technology
Anti-corrosion coatings such as epoxy resins, polyurethanes and fluorocarbon coatings are applied to the inner and outer surfaces to form a barrier layer to reduce direct contact between the medium and the metal. The coating should have good adhesion and wear resistance.
Application of non-metallic materials
Some pipes and containers are made of plastic materials such as polyethylene (PE) and polypropylene (PP), which have excellent chemical corrosion resistance and are suitable for low-temperature non-high-pressure emission systems.

Corrosion monitoring and detection technology
Online corrosion monitoring
Use corrosion rate monitoring instruments to detect metal loss in real time and warn of corrosion risks in advance. Electrochemical impedance spectroscopy and corrosion potential monitoring technology are widely used.
Non-destructive testing methods
Non-destructive testing technologies such as ultrasonic testing, radiography and magnetic particle flaw detection are used to locate corrosion defects inside equipment to ensure safe operation.
Analysis of chemical composition of medium
Regularly analyze the concentration of corrosive substances in waste gas and wastewater, optimize the treatment process, and reduce corrosion factors.

Corrosion protection process and maintenance measures
Cathode protection technology
Through external current or sacrificial anode, electrochemical corrosion reactions are suppressed and widely used in underground pipeline and storage tank protection.
Control medium conditions
Adjust the pH value of waste gas and wastewater, reduce the concentration of harmful ions, and use chemical inhibitors to reduce the corrosion reaction rate.
Regular maintenance and overhaul
Clean up scaling and corrosion products in time, repair damaged coatings, replace aging equipment, and prevent corrosion from spreading.
Design optimization
Reasonably design pipeline flow rate, avoid dead corners and gas-liquid retention areas, and reduce local corrosion. Select appropriate connection methods to reduce the risk of galvanic corrosion.