As a welding subcontractor, you provide welding services on a contract basis. Your responsibilities are to weld pipes or metal during a construction project. However, your specific duties may vary depending on the requirements of each project or contract. Some welders specialize in fitting and welding pipes or structural steel installations, while other professionals weld or solder steel or aluminum pieces together as part of a manufacturing project. In addition to operating welding equipment, clients may expect you to prepare surfaces for welding as well as inspect and test your work after completion.