plumber inspects piping for heat installation;the mechanic - the repairman tightens bolts on a flanged connection of pipeline

armature boiler bolts connection control diagnoses drilling energy engineer equipment exploration factory fitter fittings flange flanged fuel gas gate head heat heater heating helmet house industry inspects installation maintenance man mechanic mining new nut oil overalls petrochemical petroleum pipe pipeline piping plumber power production profession pump repair repairman service technician technologies technology tightens tool using valve water well work worker workman wrench