A pipefitter is a tradesperson who installs, assembles, fabricates, maintains and repairs mechanical piping systems. Pipefitters usually begin as helpers or apprentices. Journeyman pipefitters deal with industrial/commercial/marine piping and heating/cooling systems. Typical industrial process pipe is under high pressure, which requires metals such as carbon steel, stainless steel, and many different alloy metals fused together through precise cutting, threading, grooving (Victaulic), bending and welding. A plumber concentrates on lower pressure piping systems for sewage and potable water (tap water), in the industrial, commercial, institutional, or residential atmosphere.