Duplex heat exchanger prevents corrosion
06 December 2018
The corrosion rate is an important indicator for assessing the corrosion resistance of metals. When the metal is subjected to corrosion, its weight, structure, shape, surface state, mechanical properties, etc. will change. The macroscopic and microscopic rate of change can be used to reflect the degree of metal corrosion, so there will be different corrosion rate tests. Commonly used methods for air cooled heat exchanger tube bundles are: electrical resistance method, weight loss method, linear polarization method, etc.
Choosing the correct materials is one of the key process to control corrosion degree, and the following principles are: firstly, the corrosion resistance of the material should meet the requirements of the equipment environment and the characteristics of the medium - such as the corrosion type and rate, sensitivity, etc.; secondly, the physical and mechanical properties, as well as the processing performance of materials should meet the design and processing requirements, including necessary strength, hardness, impact toughness, fatigue properties, heat resistance, weldability and so on. For air cooled heat exchanger tube bundles, under the conditions of media containing hydrogen and sulfur, it is better to choose nickel-based alloy, and duplex stainless steel, which is a new type of material with excellent corrosion resistance, high strength and easy manufacturing. The physical property of duplex stainless steel is between austenitic stainless steel and ferritic stainless steel.
The design of air cooled heat exchangers must proceed from anti-corrosion and be based on materials and environment with strict calculation, certain working stress and reasonable anti-corrosion structure design.
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