To build a high-quality stainless steel chemical ship, the following key considerations need to be considered:
🔩 Material selection: Balancing of duplex stainless steel
The material of the cargo hold is the core that determines the performance and cost of a ship. The current mainstream choices include duplex stainless steel and austenitic stainless steel.
Dual phase stainless steel (such as 2205): It combines high strength (yield strength of 400-550MPa) and excellent corrosion resistance, especially suitable for seawater and acidic chemical environments. More and more are being used for building chemical tankers.
Austenitic stainless steel (such as 316L): It has good corrosion resistance and weldability, and is widely used in pipe systems and other components.
Choosing which materials requires a balance between initial investment and long-term maintenance. Although the initial cost of stainless steel cargo holds is higher, their advantages of no coating maintenance, easy cleaning, and strong cargo adaptability make them significantly economical throughout the entire lifecycle when transporting high-purity or highly corrosive goods.
🔥 Welding process: precise control of quality and deformation
Welding is one of the most technically challenging stages in the construction of stainless steel chemical tankers.
Welding methods: Depending on the location, automatic submerged arc welding (splicing), CO ₂ gas shielded welding (structure and closure seam), and manual arc welding/tungsten inert gas welding (narrow areas and repairs) are commonly used.
Key parameter control: It is crucial to strictly control the welding heat input. To maintain material properties, the interlayer temperature of duplex stainless steel usually needs to be controlled below 150 ° C, and there should be no preheating before welding and no heat treatment after welding.
Deformation control: Stainless steel has a high coefficient of expansion and low thermal conductivity, and welding deformation is one of the core challenges. Comprehensive measures such as using anti deformation fixtures, optimizing assembly sequence, and adopting reasonable welding parameters are required.
🛡️ Surface treatment and anti-corrosion: details determine success or failure
The “stainless” characteristics of stainless steel depend on its dense passivation layer on the surface, and surface quality damage will directly lead to corrosion.
Full process protection: protective measures must be taken at every step from lifting, transportation to cutting and assembly to prevent scratches and bumps.
Pollution prevention isolation: Direct contact between stainless steel and carbon steel is strictly prohibited during construction. Usually, 304 or 316L stainless steel materials are used for isolation to prevent “carburizing corrosion”.
Acid pickling and passivation: After construction is completed, professional acid pickling and passivation treatment is required to restore and strengthen its surface corrosion resistance.
