Convert barge to solid flat-bottom hold to be unloaded with an excavator.
The hold-floor-plates were 20mm thickness, to be "excavator-bucket proof". A lot of weld metal to deposit for a single-sided weld V-prep given only top access.
Productivity had been fairly pathetic.
The barge had been lingering around for far too long, and there was no chance of this type of job becoming a repeat without doing much better.
Getting to the point: I could see that for depositing so much metal over such a large job, a single good type of large SMAW electrode was needed.
I put in an order via the office for 6mm "7018" (Calcium Carbonate
based) electrodes through their familiar supplier.
Result : the owner coming out red-faced and shouting...
I had the choice of being sacked withing about 0.7 seconds (tell him
he was wrong) and being sacked in about 7 months (job went slow and I
never got a chance to deliver my abilities).
Given I was getting a lot out of the marine / maritime side of the
job, I went with the latter.
What was missed in the moment...
For given plate thickness:
Butt weld, rather than fillet weld - plus one rod size
This is about "combined thickness", or you can think about in terms of how many directions the heat can go. How much volume and weight of metal is conducting-away the weld heat.
Next; in addition
Already hot plate preheated by "root" and "hot-pass" runs, not cold plate - plus one rod size
Same variable of cold plate -> hot plate - effect on characteristic of the electrode burn
With warm plate both the minimum usable Amps and the maximum usable Amps go down.
So that's up two rod-sizes.
With the welding machine running 4mm electrodes on a cold fillet weld,
it should have run 6mm electrodes on an already hot butt weld.
The 5mm rods were ejecting-out "cannonball-spatter" as one welder
tried to get productivity with Amps the welding machine would clearly
deliver. That spatter defeated the intention of productivity.
However, another almost-certaint indication one bigger rod size would
run at the Amps the welding machine would readily give.
I was far from the only one knowing of "combined thickness" and the effects of temperature. I blagged some 6mm 7018's and we would have heated offcuts until water sizzled on them, presented an outside corner to easily mimic a butt-weld then seen if the rods would run at the Amps of a cold fillet-weld with 4mm rods. So that at least us the welders could know for sure.
None of us welders there at the time had ever used 6mm rods.
It was that £150 punt on a seemingly very high likelihood of
getting the productivity needed to make that job viable and get plenty
more of the same.
Had they worked, the 6mm rods would have given a long burn - lot of metal per rod - hopefully giving easy low-fatigue welding to do entire shifts welding at optimal rate and quality.
With Covid coming along we went our separate ways and the rods never got tried.
(R. Smith, 04Aug2023 to 05Aug2023)