Duplex heat exchanger, components

Fig. 13-20. Components of a duplex heat exchanger fabricated of Inconel clad with type-316 stainless steel.

The compatibility of INOR-8 and sodium is adequate in the temperature range presently contemplated for molten-salt reactor heat-exchanger operation. At higher temperatures, mass transfer could become a problem, and therefore the fabrication of duplex tubing has been investigated. Satisfactory duplex tubing has been made that consists of Inconel clad with type-316 stainless steel, and components for a duplex heat exchanger have been fabricated, as shown in Fig. 13-20. 

The use of stainless steel in oil production has increased, and is of particular significance for production in deep waters. This applies both to production and process equipment carrying oil and gas and to seawater systems. For seawater systems the experience from nuclear power plants has been useful. In these plants, some high-alloy steels have performed well in equipments such as seawater pumps and heat exchangers. But the performance depends on service conditions, design and combination of materials. On the oil/gas side, good experience has been obtained with 13% Cr steel in production tubing, in components at the wellhead and in well valves. The same can be said about the use of other stainless steels in process systems offshore, but there have been some exceptions. For instance, SCC has occurred on duplex steel (22-5-3) under external heat insulation (compare Section 7.12) [10.11]. 

Table 7 Corrosion conditions in heat exchangers exposed to waste waters from oil refining for components made of ferritic-austenitic steel (duplex steel) UNS S31500 (3RE60,1.4417) [26, 27]...

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