304L-alloy: This alloy is both economical and versatile. It does a great job preventing corrosion in wood burning environments and wood burning applications. 304L is significantly different from basic 304 stainless steel, as it is much more resilient to corrosives and rust. This makes it an excellent choice for solid fuels such as wood or wood pellets.
316L-alloy: This alloy has more molybdeenum and nickel and slightly less chromium than 304-alloy. The result of these slight differences is that the 316 stainless steel is substantially more resistant to corrosion. Taking this one level further, 316L is processed as a low-carbon alloy, making it more resistant to corrosion than basic 316. 316L is an excellent alloy for coal, oil, and non-condensing or lower efficiency gas appliances.
316Ti-alloy: With the added molbdenum and titanium in this alloy, you'll enjoy excellent corrosion resistance in acidic environments and high heat corrosion resistance. This durable stainless steel alloy is a great choice for wood, coal, oil and non-condensing gas.
AL29-4c-alloy The most corrosion resistant of all alloys, this alloy is a superferritic stainless steel designed by Allegheny Ludlum in the early 1980's. It is good for all gas appliances, especially higher efficiency, high-condensing appliances. AL29-4C works best for combating the high acidic bi-product of burning corn. With the lower temperatures of burning corn and high-efficiency gas furnaces, this alloy is the best choice; however, it is not as good as 316Ti in high temperature environments.