Welding positions: PA to PG and the ISO 6947 codes
The position is not a detail of how you stand. It changes the current, the electrode diameter, the technique and — through the qualification range — what you are allowed to weld at all.
The codes
| ISO 6947 | Name | AWS | What it means |
|---|---|---|---|
| PA | Flat | 1G / 1F | Weld from above onto a horizontal joint. The easiest, and the fastest. |
| PB | Horizontal-vertical | 2F | A fillet in the corner between a horizontal and a vertical plate. |
| PC | Horizontal | 2G | A horizontal weld on a vertical surface. Gravity pulls the pool downwards. |
| PD | Horizontal-overhead | 4F | An overhead fillet. Uncomfortable and slow. |
| PE | Overhead | 4G | Welding above your head. Everything is working against you. |
| PF | Vertical up | 3G up | Vertical, welding upwards. Good penetration, slow. |
| PG | Vertical down | 3G down | Vertical, welding downwards. Fast, shallow penetration. |
| PH | Pipe, vertical up | 5G | Fixed horizontal pipe, welded upwards around it. |
| H-L045 | Pipe at 45° | 6G | Fixed pipe at 45°. The broadest single qualification there is. |
Why the position changes the settings
Everything follows from one fact: in the flat position, gravity holds the pool in the joint, and in every other position it does not. A pool that gravity is pulling out of the joint has to be small, and a small pool means less current, a smaller electrode and a technique that gives the metal time to freeze.
In practice: drop the current about 10 % for vertical and 15 % for overhead — the current calculator applies this. Keep the electrode at 4 mm or below: 5 and 6 mm electrodes are effectively unusable vertically because the pool becomes too large to hold.
Technique by position
PF, vertical up. The shelf of frozen metal below the pool supports it, so the weld climbs on its own foundation. Weave in a triangle or a Christmas-tree pattern with a pause at each edge — the pause is what fills the toes and prevents undercut. The root run is often made without weaving at all.
PG, vertical down. Fast, and the arc runs ahead of the pool so penetration is shallow. Excellent on thin sheet and on cellulosic root runs, and a reliable way to produce lack of fusion on anything thick.
PC, horizontal. The pool wants to sag onto the lower plate. Use stringer runs rather than weaving, keep the electrode angled slightly upwards and build the weld from the bottom up.
PE, overhead. Minimum current that will still fuse, the shortest arc you can hold, small stringers and no weaving. Everything that falls lands on you, so the PPE matters more here than anywhere — see personal protective equipment.
The position on your certificate
The position in which you took the test decides which positions your certificate covers, and the rule runs one way: harder covers easier. Which positions a given test covers is worked out by the qualification range calculator.
Frequently asked questions
Does a PF qualification cover PA?
Yes. Positions cover downwards in difficulty: a test in PF covers PA and PB, while a test in PA covers little beyond itself. That is why examiners suggest sitting the harder position even though the pass rate is lower.
PF or PG — up or down?
PF is vertical up and PG is vertical down. Up gives penetration and is what structural work asks for; down is fast and shallow and belongs on thin sheet and on cellulosic pipeline root runs. Using PG where the drawing wanted PF is a classic cause of lack of fusion.
How do the ISO and AWS position codes relate?
They describe the same positions with different labels: PA is roughly 1G/1F, PC is 2G, PF is 3G upwards, PE is 4G, and the pipe positions PH and H-L045 correspond to 5G and 6G. The correspondence is close but not exact, so a certificate is read in the system it was issued in.
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