Pipe welding positions: 1G, 2G, 5G and 6G
With pipe, two things decide everything: how it lies and whether it turns. A rotated pipe means welding in one comfortable position; a fixed pipe means walking the circumference through overhead, vertical and flat — all in a single run.
The four set-ups worth knowing
The American symbols 1G to 6G describe how the pipe is placed; the European ones to EN ISO 6947 describe the position the weld actually sits in. That is why one 5G set-up answers to two European notations: PF when you run uphill and PG when you run down.
| EN ISO 6947 | AWS | Pipe | The weld runs |
|---|---|---|---|
| PA | 1G | rotated, horizontal | flat |
| PC | 2G | fixed, vertical | horizontal |
| PF | 5G | fixed, horizontal | uphill through overhead |
| PG | 5G | fixed, horizontal | downhill |
| H-L045 | 6G | fixed, at 45° | all of them in turn |
How 5G is welded
Divide the circumference into quarters in your head and weld uphill on both sides, like two letter Cs. Start a few millimetres before the bottom dead centre so the start of the bead does not land exactly in the root. The position changes as you go: the bottom is overhead, the sides vertical, the top flat — and the current has to be a compromise between all three.
Why 6G is the hardest test
The pipe sits at 45° and does not turn, so no position on the circumference ever repeats: every centimetre is a different angle. That is why a qualification passed in 6G covers practically every other set-up, and why the test counts as a welder coming of age.
The root run and penetration
On pipe you are judged not only on the cap but on the root from the inside, and the inside is usually out of reach. Hence two solutions: TIG for the root with stick or wire for the fill, or a cellulosic electrode run downhill. On stainless add an argon purge, without which the root oxidises and crumbles away.
What the qualification covers
Under EN ISO 9606-1 a test on pipe also covers plate, but not the other way round. The diameter range is worked out from the test piece diameter, and the 6G set-up is written H-L045. The exact range further depends on thickness, joint type and whether the root was welded without a backing.
Frequently asked questions
What is the difference between 5G and 6G?
In 5G the pipe lies horizontal and does not turn; in 6G it sits at 45° and does not turn either. In 6G no position on the circumference ever repeats, so it is harder and it covers a wider qualification range.
Does a pipe qualification cover plate?
Yes. Under EN ISO 9606-1 a test on pipe also covers plate, but not the other way round: a plate qualification does not cover pipe.
Where do you start the bead in the 5G position?
A few millimetres before bottom dead centre, so that the start of the bead — the weakest spot — does not land exactly in the root.
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