A welding system with variable environment system is provided that allows devices to be welded in different gas environments. The preferred welding system uses a controllable gas delivery system that provides different gas mixtures to a welding chamber at different times. Thus, welding in different gas mixtures can be performed in a single welding chamber. This allows the devices to be welded both in environments that promote effective welding and in environments that have specific characteristics desirable for gases that remain in the completed device. Thus the system facilitates the formation of different types of devices in a single welding chamber, and in a single manufacturing line.