Gas tungsten arc welding (GTAW), also known as tungsten inert gas (TIG) welding, is an arc welding process that uses a non-consumable tungsten electrode to produce the weld. The weld area and electrode are protected from oxidation or other atmospheric contamination by an inert shielding gas (argon or helium). A filler metal is normally used, though some welds, known as autogenous welds, or fusion welds do not require it. When helium is used, this is known as heliarc welding. A constant-current welding power supply produces electrical energy, which is conducted across the arc through a column of highly ionized gas and metal vapors known as a plasma. GTAW is most commonly used to weld thin sections of stainless steel and non-ferrous metals such as aluminum, magnesium, and copper alloys. The process grants the operator greater control over the weld than competing processes such as shielded metal arc welding and gas metal arc welding, allowing for stronger, higher quality welds. However, GTAW is comparatively more complex and difficult to master, and furthermore, it is significantly slower than most other welding techniques. A related process, plasma arc welding, uses a slightly different welding torch to create a more focused welding arc and as a result is often automated.
Gainsborough is a market town in the West Lindsey district of Lincolnshire, England. The population of the town was 20,842 at the 2011 census. It is situated on the River Trent, 18 miles (29 km) north-west from the city and county town of Lincoln, 15 miles (24 km) south-west of Scunthorpe, and 35 miles (56 km) east of Sheffield. At one time it served as an important port with trade downstream to Hull, and was the most inland port in England, being more than 55 miles (90 km) from the North Sea.