Final answer:
The most common material for refinery plant piping is carbon steel due to its durability and cost-effectiveness, followed by stainless steel and alloys for more extreme conditions.
Step-by-step explanation:
The most common type of material used to make refinery plant piping is carbon steel. This choice of material is due to its durability, cost-effectiveness, and ability to withstand the harsh conditions present in a refinery, such as high temperatures and pressures. Carbon steel piping is manufactured in various grades to cater to different pressure ratings and chemical resistance needs. Stainless steel is also widely used for its corrosion resistance properties, especially where the piping may be exposed to corrosive substances or environments. Alloy materials, like chrome-molybdenum steel, are selected for more extreme conditions that require greater strength and temperature resistance.