Starting TIG-pipe weld-training Dec2012

The start...

Initial stage of training was getting hand back in and general concepts practicing TIG-rooting 8mm mild-steel plate V-butts.
Then on to pipe. Again starting with mild steel. Pipe is nominal 4-inch. Cheap and quick to saw off pieces and manually bevel with angle-grinder.

TIG being TIG - already huge early-stage surprise! For most welding processes plate is easy and pipe is difficult. With TIG I am finding the opposite - pipe often and in many ways seems easier than plate for all except on-the-flat (1G (AWS); PA (ISO))...!

These early-stage pictures with comment...

Here is how things stand at end of first push - about a week

[in centre] early walk-the-cup - this being a cover-pass / cap-bead
[to LHS] root bead - cool small root weld using narrower root-gap

Regarding the walk-the-cup:

it does work well (given caveats)
a very regular looking weld is possible
the wrist / hand action is interesting to learn
used for root-run, the method does not seem to be able to adapt its penetration - saw lack-of-penetration defects with skilled welder, where when I was "floating the torch" even I was able to compensate for joint fit-up and keep root penetration going

Regarding the root-run:

where root-gap is larger than filler-wire diameter and can pass filler-wire through bore, am able to get penetration bead most of the time
for root-welds where filler-wire diameter is larger than root-gap, can get small fast weld with low heat input (as seen in pic. above)
doing TIG "5G" - go all way around pipe - is very challenging (must try "6G" - for TIG is easier than "5G ???")
Some facts - on nominal 4inch pipe (about 6mm wall thickness) - using about 95A to 105A depending on root gap; filler wire 2.4mm diameter; tungsten stickout about 5mm; about 6l/min to 8l/min argon flow

Obviously the finish of my welding "offers an abundance of room for improvement". However, there's some things I can say compared to just over a week ago when I started:

"floating to torch" over much more complex geometries than ever before
freely doing both Left-hand and Right-hand TIG with equal ability
I've learned a lot
had many realisations important to my welding-engineering / metallurgical work

Attending to details...

Struggling to see through low-end well-used and much-scratched auto-darkening helmets.
Went bought this traditional filter welding helmet - got shades #9, #10 and #11. Most of my TIG at around 80A to 120A should be on shade #10. Good traditional fixed-shade visor and you can see clearly in colour when arc on, as if seeing in conventional light / illumination.
When TIG'ing, you tend to have long arc-on times and few stop-starts, so lesser disadvantage of fixed shade visor.
TIG welding is notorious for needing top-end auto-darkeners anyway, on two counts:

seeing clearly - with manipulating the torch with tungsten just above the melt pool and feeding the wire into the melt pool - without colliding with the tungsten!
visor correctly darkens and lightens at right moments - need good logic and sensitivity of triggering mechanism, as cheaper auto-darkeners get it wrong and "lose (sight) of the arc", brightening the visor and leaving the welder dazzled

The piece of stainless steel filler wire is for practicing the feeding action. Ends smoothed and bent-around for safety. Want to be considerate when sat there on the train with you TIG gloves on practicing your feeding action back-and-forth, back-and-forth... regaining the technique and strengthening the necessary muscles.

Background comment

Finding root gap which can pass filler wire through necessary. Can pass filler wire through bore of pipe. Problem is that root gap tends to close-up. Need wedges? To place in root gap and prevent it closing up. Hammer out when approaching with weld.

RSmith - 08Dec2012, 13Dec2012