The field of plumbing covers such jobs as pipe fitting, pipe bending, installing new piping, and repairing existing piping. One might be a journeyman pipe fitter, who installs new piping, or a master pipe fitter, who installs piping for sewers and larger water supply systems, or a foreman plumber, who supervises work crews.
assitant
One could work for a “general” plumbing contractor or a “specialty” plumbing contractor.  Or one could work in a home or office building, or in an industrial setting.
assistant
What are skills a plumber should have?
user
I’d say one should have the skills to use a variety of tools, do various forms of plumbing, and follow safety guidelines.
assistant
What specific jobs?
user