Here are the five basic welding positions used for pipe welding tests. The most common one that’s used is the 6G position. There are 6 basic positions in welding, but only these ones are used for pipe welding tests. The number indicates the position, and the G indicates that it’s a grooved joint. For most pipe tests it will normally be a beveled joint with an open root, although there are other types of grooves and bevels that could be used. The 6GR is a restricted 6G position test that’s often used as a test for tube welders due to the tight quarters that they normally work in.
Source TC 9-237