Hello all
Hilarious driving home of a lesson about electrodes and the polarity they need.
Yesterday, all way from 0730 to morning break at 10am, had the welding machine on DCEN for 7016 rods. Did metres (yards) of weld.
I did have a properly formed weld-pool at all times, it must be said.
Swapping to correct (DCEP) polarity, the welds were twice as fast and twice as good.
The mea culpa bit.
My colleague helped me set up my next rubbing strake - capped with 5mm flat. Tacked it in place. He knew it is unnecessary to remove paint and generally clean, so helped me by tacking it down over paint. Well, the weld-pool was boiling like a witch's cauldron with pyrolised hydrocarbon residue of incinerated paint blowing through it. Plus I sometimes could see white smoke travelling up inside my visor from where it had jetted-out in just the right direction. Not happy on at least two accounts. The pleasant ambience of the day was detracted from by much profanities, it could be confessed.
I asked my colleague how he got his neat welds (there were, fairly). Well, it was like it being demonstrated that someone with Parkinson's Disease can be a good welder. He was whipping and dodging the rod around like mad - something like out to 40mm of outriding - while overall puddling-up a reasonable weld-pool inspite of all the blowing-out smoke and everything. Then lifted his visor and asked "Well, what was so difficult about that?". Myself being mindful that many would say that for any Basic (Calcium Carbonate based) flux - 7015/7016/7018 - you are supposed to keep a very short arc and move very slowly were you to as much as weave at all.
Obviously, I'd never thought to practice 7016 while imitating having the "Saint Vitus' dance" ailment - so felt short of prior experience in his technique.
Surveying the double figures of metres of welding still to do, I cut the tacks, chopped off the rubbing strake where weld so far finished, with a slitting disk in an angle-grinder, and fetched the diesel-driven air compressor and the needle-gun.
It took 2 minutes a metres to clean down clean bare metal along the top of the strake. Where paint had been, it came out silver. Nothing re. time, in the overall task.
I tacked back on, then got the first couple of inches of the strake welded back on. Then grooved-out the joint and welded the strake back together. Well, in the 9/10ths darkness of the winter night already closed-in at end of the working day, there I was, lying on the hull, looking mesmerised at these three flames like a cross between a birthday-cake candle and a gas lighter set excessively high, evenly-spaced across my weld, giving a clear steady beautiful light. I didn't reach for my mobile device to take a picture, as it would be all over too soon and I would miss the beauty of the three flame-jets firing out of the three pores tunneled through the 5mm depth of my weld. Except I would have had time - they went on and on and on as I revelled in the beauty of the light - yellow enough to be warm but white enough to light my work area. So that hydrocarbon residue was all coming from the half of the weld - the side under the strake already there which had been laid over paint.
So when the next day at 0730 I changed my mind from starting doing some minor work with small 6013's on DCEN and went straight for the main strakes with 7016's and forgot to change the polarity, and didn't register the rasping arc and other obvious protests about wrong polarity - I offer in explanation my previous day messing-up my recent reference-norm...
Mea culpa...
Back on DCEP, yes? The welds flowed-in fast and smooth, with a wide "sweet-spot" of good welding conditions.
PS - 'nother advantage of using the needle (de)scaler, BTW... My colleague's quick sweep with an angle-grinder filled the air with paint dust and rust, despite leaving most of both in place. Not happy about the dust as I was there welding the previous strake. Needle-gun - you eject spalled-off scabs of paint and rust - which scatter around and there is zero air-borne. Vastly preferable.
Etc.
Best wishes