Surface chemistry of cooking
Stainless steel is considered stainless because it has at least 11% chromium by mass. Chromium is a relatively inert metal and does not rust or react as easily as plain carbon steel. This is what makes it an exceptional material for cooking. It is also fairly inexpensive, but does not have a very high thermal conductivity. From a surface standpoint, this is because of the thin layer of chromium oxide that is formed on the surface. This thin layer protects the metal from rusting or corroding. While it is protective, the oxide layer is not very conductive, which makes cooking food less efficient than it could be. For most cooking applications, high thermal conductivity is desirable to create an evenly heated surface on which to cook. In this way, stainless steel is usually not considered high-grade cookware.
Chimney
Metal liners may be stainless steel, aluminum, or galvanized iron and may be flexible or rigid pipes. Stainless steel is made in several types and thicknesses. Type 304 is used with firewood, wood pellet fuel, and non-condensing oil appliances, types 316 and 321 with coal, and type AL 29-4C is used with non-condensing gas appliances. Stainless steel liners must have a cap and be insulated if they service solid fuel appliances, but following the manufacturer's instructions carefully. Aluminum and galvanized steel chimneys are known as class A and class B chimneys. Class A are either an insulated, double wall stainless steel pipe or triple wall, air-insulated pipe often known by its genericized trade name Metalbestos. Class B are uninsulated double wall pipes often called B-vent, and are only used to vent non-condensing gas appliances. These may have an aluminum inside layer and galvanized steel outside layer.