In the chemical industry, can Carbon Steel Pipeline withstand the corrosion of acids and alkalis?

In the chemical industry, whether carbon steel pipelines can withstand acid and alkali corrosion depends on the specific acid and alkali types, concentrations, temperatures, and surface treatment and protection measures of the pipelines. The following is a detailed analysis:

Basic corrosion resistance of carbon steel pipelines
Limitations of carbon steel
Carbon steel itself has limited tolerance to chemicals such as acids and alkalis, especially under high concentration or high temperature conditions, and is prone to corrosion.
In an acidic environment, carbon steel will undergo chemical reactions to generate soluble iron salts, causing the material to be gradually corroded.
In an alkaline environment, carbon steel may undergo alkali embrittlement (alkali stress corrosion cracking), especially in high temperature and high concentration alkali solutions.
Factors affecting corrosion
Types of acids and alkalis: The degree of corrosion of carbon steel by different acids and alkalis varies greatly. For example:
Hydrochloric acid and sulfuric acid are highly corrosive to carbon steel.
Dilute nitric acid may form a passivation layer to slow down corrosion.
Sodium hydroxide (NaOH) may cause alkali embrittlement at high temperatures.
Concentration and temperature: The higher the concentration of the acid and alkali and the higher the temperature, the faster the corrosion rate.
Flow rate: Acid and alkali solutions flowing at high speeds will accelerate corrosion, especially in turbulent areas.
Methods to improve the corrosion resistance of carbon steel pipelines
In order to enhance the tolerance of carbon steel pipelines in acid and alkali environments, the following measures can be taken:
Surface coating
Inner wall coating: By applying an anti-corrosion coating (such as epoxy resin, polyurethane or phenolic resin) on the inner wall of the carbon steel pipeline, the contact between acid and alkali and the carbon steel substrate can be effectively isolated.
Outer wall coating: Used for buried pipelines to prevent acidic substances or moisture in the soil from corroding the pipeline.
Lining technology

Rubber lining: Natural rubber or synthetic rubber is lined inside the pipeline, which is suitable for conveying low-concentration acid and alkali solutions.
Plastic lining: Plastic materials such as polytetrafluoroethylene (PTFE), polypropylene (PP) or polyvinylidene fluoride (PVDF) are used as linings, which can withstand strong acids, strong alkalis and high temperatures.
Fiberglass lining: Provides higher corrosion resistance and mechanical strength through fiberglass reinforced plastic (FRP) lining.
Alloying
In some cases, low alloy steel pipelines with added elements such as chromium, nickel, and molybdenum can be selected to improve their corrosion resistance. For example:
Carbon steel containing chromium has better tolerance to oxidizing acids (such as nitric acid).
Carbon steel containing molybdenum has stronger resistance to pitting and crevice corrosion caused by chlorides.
Cathodic protection
For buried pipelines, cathodic protection techniques (such as sacrificial anode method or impressed current method) can be used to reduce the corrosion of carbon steel pipelines by acidic soil.
Regular maintenance
Regularly check the surface and coating condition of the pipeline and repair the damaged parts in time.
Use corrosion inhibitors to reduce the corrosion rate of acid and alkali on carbon steel.
Applicable scenario analysis
Weak acid and weak alkali environment
Carbon steel pipelines can be used to transport dilute acids (such as dilute sulfuric acid, dilute hydrochloric acid) or low concentration alkali solutions (such as sodium hydroxide solution) after appropriate surface treatment.
For example, in some water treatment or food processing processes, carbon steel pipelines can meet the needs.
Strong acid and strong alkali environment
In strong acid (such as concentrated sulfuric acid, concentrated nitric acid) or strong alkali (such as high temperature sodium hydroxide solution) environment, ordinary carbon steel pipelines are usually not suitable, and materials with higher corrosion resistance (such as stainless steel, Hastelloy or titanium alloy) must be used.
If carbon steel pipelines must be used, lining or coating technology must be combined for protection.
High temperature and high pressure environment
Acid and alkali solutions under high temperature and high pressure conditions are significantly more corrosive to carbon steel pipelines, so specially designed pipelines (such as duplex stainless steel or lined pipelines) need to be selected.

Through scientific design and strict maintenance, carbon steel pipelines can play an important role in many chemical applications while ensuring safety and economy.