Contractor whose job is to install piping for steam, cooling, hot water, etc.

A pipefitter (also called steamfitter) is someone who lays out, assembles, fabricates, maintains and repairs piping systems. A plumber is a type of pipefitter who concentrates on piping systems for liquids (potable water, sewage, etc); other types of piping systems include steam, ventilation, hydraulics, chemicals or fuel.