The specific applications of duplex stainless steel in the chemical industry

Duplex stainless steel has many specific application cases in the chemical industry. Here are some common ones: 

Vinyl chloride production facility

Qilu Petrochemical Company: When producing vinyl chloride by the oxychlorination method, the cooling coils in the oxychlorination reactor use imported SAF2205 steel pipes. The reaction environment in the oxychlorination reactor is extremely harsh, with media such as HCl, water vapor, and dichloroethane in the shell side, a temperature of 230°C, and a pressure of 0.2 MPa. The duplex stainless steel can work stably in this environment. The gas coming out of the oxychlorination reactor enters the pre-cooler (air cooler), and the foreign ones with aluminum fins are mostly made of 3RE60 steel or 2205 steel. The vinyl chloride reboiler also often uses this type of duplex stainless steel. The EDC containing trace amounts of hydrochloric acid flows inside the tubes at 100°C and 1.2 MPa, while the shell side is filled with steam at 200-230°C and 1.3 MPa. The 3RE60 steel can be used for 5 years without damage. 

Methanol synthesis reactor

Domestic methanol plant: The catalyst tubes of small methanol synthesis reactors are mostly made of 00Cr18Ni5Mo3Si2 steel, while large and medium-sized ones use 00Cr22Ni5Mo3N steel. The tube side is CO, H₂, and CH₃OH synthesis gas at 265°C and 5.2 MPa, and the shell side is steam and deionized water at 250-265°C and 3.9-5.1 MPa. The high-pressure equipment made of duplex stainless steel has no corrosion for 10 years. In addition to the reactor, the material/flowout heat exchangers, pipeline systems, etc. in foreign countries also use duplex stainless steel.

Organic acid production facilities such as acetic acid

Sellenis Company: In the production of acetic acid, some pipelines and heat exchangers involving high-temperature acetic acid and acetic acid vapor use duplex stainless steel. Acetic acid is corrosive, especially in high-temperature environments, and ordinary stainless steel is difficult to resist corrosion and cannot withstand it. However, duplex stainless steel with its excellent corrosion resistance can ensure that the equipment is not corroded during long-term operation, reducing maintenance and replacement costs.

Sulfuric acid production facility

A large sulfuric acid plant: In the sulfuric acid cooler and dilute sulfuric acid transportation pipelines, SAF3006 super duplex stainless steel is used. In the sulfuric acid production process, both concentrated and dilute sulfuric acid are highly corrosive, and ordinary materials are prone to corrosion perforation. SAF3006 super duplex stainless steel is specially developed for acidic environments and can effectively resist the corrosion of sulfuric acid, ensuring the normal operation of the cooler and pipelines and guaranteeing the continuity of production.

Caustic soda production facility

Chlor-alkali chemical enterprise: In the alkali liquid evaporation section of caustic soda evaporation, duplex stainless steel is used in the alkali liquid evaporation. The alkali liquid in caustic soda production has strong alkalinity and is at a high temperature during evaporation， requiring high corrosion resistance and heat resistance of the equipment materials. Duplex stainless steel can withstand the corrosion of the alkali liquid and the high-temperature effect， ensuring the stable operation of the evaporation and improving the efficiency and quality of caustic soda production.