Material selection for high-temperature, high-humidity, corrosive flue gases

C276 has poor corrosion resistance at 350 degrees.

It is recommended to use Corten steel 09CuPCrNi. Corten steel is a type of weathering steel, that is, steel resistant to atmospheric corrosion. Element composition: C: 0.06, Si: 0.57, Mn: 0.74, P: 0.018, S: 0.013, Ni: 0.71, Cr: 0.53, Mo: 0.01, V: 0.01, Cu: 0.46 (values in %). It is used in applications involving sulfur-containing flue gases, air preheaters, economizers, and boiler air preheaters, as well as in situations where protection against acid dew points is necessary. It belongs to the category of low-temperature weathering steels and possesses strong resistance to corrosion at low temperatures. 　　 Corten steel is a type of steel that possesses corrosion-resistant properties; when used on the exterior of buildings, it allows the building’s facade to remain without the need for protective paint. Once a \"rust layer\" is formed, corrosion resistance lasts for 80 years, eliminating the need for protective paint. ========== Note: Weathering steel is a broad category, but it originated from Corten steel. Weathering steel first emerged in North America as Corten Steel, and it is widely used in the manufacture of train carriages, containers, and bridges ； Weathering steel is used as a material for building facades, and it has a history in North America, Western Europe, Australia, as well as in Japan and South Korea in Asia. The earliest example is the Chicago Civic Center building, completed in 1965, featuring an exposed weather-resistant steel structure along with a mixed curtain wall of weather-resistant steel plates and glass. 　　The main technical advantage that enables weathering-resistant steel plates to be used as facade materials is their superior corrosion resistance compared to ordinary steel. Under natural climate conditions, steel can thin by more than 0.1–1 mm over 5 years due to corrosion; the thinning is even more severe over longer periods or in special and artificially harsh environments. Weathering steel (taking Wugang’s products as an example) incorporates weathering-resistant elements such as copper, chromium, and nickel, which enable the steel material to form a dense oxide layer about 50–100 μm thick between the rust layer and the base metal; this oxide layer has good adhesion to the base metal. This special dense oxide layer has a stable, uniform natural rust-red color. 　　 　Steel structures have many advantages, such as high strength and toughness, seismic resistance, light weight which reduces the cost of foundations, low cost, the ability to accommodate large open spaces and flexible division to increase the usable area by 5%-8%, no need for civil engineering materials, the possibility of prefabrication in factories, ease of assembly and disassembly, and short construction time. 　　 　　The purpose of Wuhan Iron and Steel Group, a domestic steel manufacturer, in developing the building-grade refractory and weather-resistant steel 09CuPCrNi-A is to enhance the steel’s high-temperature strength and resistance to atmospheric corrosion. At the same time, Wugang’s refractory and weathering-resistant steel possesses mechanical properties, welding properties, and other characteristics at room temperature that are comparable to those of ordinary construction steel. The fire and weather resistance developed by Wuhan Iron and Steel Group is comparable to that of high-weatherability COR-TEN steel in the United States, and is 3 to 8 times that of ordinary steel; it can be used exposed to the elements under normal climatic conditions. It can improve paintability, and the service life of the coating applied to weather-resistant steel is much longer than that on ordinary steel. Its fire resistance is comparable to that of fire-resistant steel used in Japanese construction; it allows the yield strength at 600 degrees Celsius to decrease by no more than 1/3 of the specified yield strength standard at room temperature. This is an essential requirement to ensure the safety of buildings in case of a fire, whereas ordinary steel can maintain this strength level only up to 350 degrees Celsius. This allows for a reduction in the use of fireproof coatings and fireproofing materials, thereby minimizing pollution, shortening construction time, increasing the usable area of buildings, reducing costs, and eliminating or minimizing the need for anti-corrosion maintenance. It is an economical type of steel that features \"environmental friendliness\" and sustainability. 　　

Can Corden steel withstand acid dew point corrosion from high-humidity flue gases? Is it suitable for use in the low-temperature economizer of boilers? Has it been used before? Please share the results.

There is a company in Shenzhen that claims to offer coatings for stainless steel, with quite good results.

What coating? Ordinary mortar cannot withstand such high temperatures and humidity; the problem is also that condensation may occur

For this application, high-silicon stainless steel or other suitable materials are required, but the cost is relatively high; it depends on whether the owner can accept that.

There’s some kind of grade or specification, but it’s hard to find information on that; most of what I’ve found are just general discussions.

The material cost is too high, titanium composite panels.

Using 310LSS for this application is feasible, and the cost is not too high either.