Steamfitters pose with piles of pipe they will cut on the job, circa 1920s

Union members of the Enterprise Association of Steamfitters Local 638, founded in 1898, once cut and threaded pipe on the job with a cutting machine (left). Today, pipe is pre-cut and pre-threaded for steam, hot water, hydraulic systems, sprinklers, pneumatic tubing, compressed air, ice machines, and air conditioning systems.