As a marine pipefitter, you are responsible for the quality, design, and build of pipes used for water purposes. You lay out, assemble, install, fabricate, repair, and maintain pipe systems and supports. You work with hydraulics, steam heat and power, hot water, and air pressure pipe systems and attach pipes to walls and fixtures with tools, brackets, or welding equipment. Using blueprints, you select the type and size of pipe, as well as the materials and equipment needed for the job. You determine the layout and monitor structural weakness and environmental obstacles while laying mechanical piping systems.