What are the differences in the operating environments for 321 and 316L?

Based on the numbers you provided, it should be more than enough.

The operating environment is as follows: medium is fuel oil; the design pressure is 1.6 MPa and the design temperature is 120°C. The pipe material required is 321, but it is not available currently. Can 316L be used as a substitute? This represents an upgrade from 321 to 316L, and it is entirely feasible to use 316L instead. But let me give you a warning: what kind of fuel oil is it? With a pressure of 16 kilograms and a temperature below 300, why use 321 or 316L? Is there severe corrosion? I think that from an economic perspective, 20% is sufficient. Of course, if your company is run by the party or funded by foreign capital and is extremely wealthy, that’s a different story, haha, just joking around. . . ;P :lol ;P

For a design pressure of 1.6 MPa and a design temperature of 120°C, such high-quality materials aren’t necessary! 316L is a stainless steel to which Mo (2–3%) has been added to achieve excellent pitting and corrosion resistance; its maximum carbon content is 0.03, and it can be used in applications where annealing after welding is not possible and maximum corrosion resistance is required. It can effectively prevent corrosion caused by high-temperature sulfur and naphthenic acids. Naphthenic acids cause severe corrosion only at temperatures between 250 and 350 degrees; at 321 degrees, such corrosion is not a concern, as the Cr5Mo material is sufficient! Even 20# is no problem!

There are a wide variety of stainless steels, each with distinct properties. Based on their microstructure, they can be classified into austenitic stainless steels, austenitic-ferritic stainless steels, ferritic stainless steels, martensitic stainless steels, and precipitation-hardening stainless steels, among others. Chromium is the most essential element that gives stainless steel its corrosion resistance; the chromium content is generally above 13%, with some grades having as much as 30%. Nickel is also a major alloying element in stainless steel, with concentrations that can reach around 20%. Nickel helps to achieve a single austenitic structure in stainless steel, thereby improving its corrosion resistance and toughness. In addition, some stainless steels also contain other elements such as molybdenum, vanadium, copper, manganese, and nitrogen. Stainless steel is mainly used to manufacture chemical equipment, medical devices, food industry equipment, and other components that require corrosion resistance. Stainless steel is not completely rust-proof; it just rusts more slowly. Acid-resistant steel, too, cannot resist the corrosion of all acids, but it exhibits greater resistance to corrosion in certain acids. For example, chromium stainless steel can resist corrosion by highly oxidizing acids, but it is not resistant to non-oxidizing acids; for instance, in hot hydrochloric acid, it corrodes even more slowly than ordinary carbon steel. Therefore, it should be selected appropriately based on the usage requirements. Using stainless steel is not the only way to address corrosion. (Austenitic stainless steels) mainly include: 321, (1Cr18Ni9Ti), also known as 18-8; 304, (0Cr18Ni9); 304L, (00Cr19Ni10); 306, (0Cr17Ni12Mo2); 316L, (00Cr17Ni14Mo2); and Mo2Ti. The main differences are as follows: 321 contains titanium, 316 contains molybdenum, 304 contains neither titanium nor molybdenum, while Mo2Ti contains both molybdenum and titanium. In terms of performance, 316L is the best, with 321/304 being of average quality. 316 and 317 stainless steels (the properties of 317 stainless steel are listed later) are types of stainless steels that contain molybdenum. The molybdenum content in 317 stainless steel is slightly higher than that in 316 stainless steel. Thanks to the molybdenum present in it, this alloy exhibits superior overall performance compared to 310 and 304 stainless steels. Under high-temperature conditions, when the concentration of sulfuric acid is below 15% or above 85%, 316 stainless steel has a wide range of applications. 316 stainless steel also has good resistance to chloride corrosion, which is why it is commonly used in marine environments. The maximum carbon content of 316L stainless steel is 0.03; it can be used in applications where annealing after welding is not possible and where maximum corrosion resistance is required. Its corrosion resistance is superior to that of 304 stainless steel, and it exhibits good corrosion resistance during the production processes in the pulp and paper industry. Moreover, 316 stainless steel is also resistant to corrosion by marine and aggressive industrial atmospheres. Heat resistance: 316 stainless steel exhibits good oxidation resistance when used intermittently at temperatures below 1600 degrees, and when used continuously at temperatures below 1700 degrees. Within the range of 800–1575 degrees, it is not advisable to expose 316 stainless steel to such conditions continuously; however, when used continuously outside this temperature range, 316 stainless steel exhibits good heat resistance. 316L stainless steel has better resistance to carbide precipitation than 316 stainless steel, and can be used within the aforementioned temperature range. Heat treatment involves annealing at temperatures between 1850 and 2050 degrees, followed by rapid annealing and then quick cooling. 316 stainless steel cannot be hardened by heat treatment. 316 stainless steel has good weldability. All standard welding methods can be used for welding. During welding, stainless steel filler rods or electrodes such as 316Cb, 316L, or 309Cb can be used depending on the application. To achieve the best corrosion resistance, the welded section of 316 stainless steel requires post-weld annealing. If 316L stainless steel is used, no post-weld annealing is required. When operating in humid atmospheric and seawater environments, titanium alloys exhibit significantly better corrosion resistance than stainless steel; they are particularly resistant to pitting corrosion, acid corrosion, and stress corrosion. They also show excellent corrosion resistance to alkalis, chlorides, organic chlorides, nitric acid, sulfuric acid, and other similar substances. ... so the opinion above is still reasonable