pipehead,
thanks for the response that contains interesting information - at least for myself!
Hmmm... unfortunately polka isn't in the mood or hasn't enhough time apparently to provide us with more details.
Thus, once again, please let me reply by interpreting polkas post from my personal standpoint.
As far as I may be wrong with this, he may correct it later on...
I guess from the data he supplied (quote):
"We weld them with using 3.20" and 4" 6010 electrodes and 3.25" and 4" 7018 electrodes..." as well as by:
1.Root Weld: 3.20 mm 6010 electrodes
2.Hot Pass: 4 mm 6010 electrodes
3.Multi Pass: 3.25 mm 7018 electrodes
4.Multi Passes: 3.25 or 4 mm 7018 electrodes ... we may suppose - unconsidered the inch designations with the first named electrode diameters - that it's an open root application. Very often a standard V-Bevel joint configuration (30° bevel angle = 60° root opening) is used for those kinds of applications -at least here in Germany - as it makes the fewest 'problems' to being easily prepared.
Even though, an appr. 78" diameter is rather not an everyday application, honestly spoken.
So, provided a 60° root opening, an 18 mm thickness and supposed they're using a 2 mm gap width, we may calculate (A = t * w + t² * tan alpha/2) a theoretical seam cross section of 246 mm². This along the pipe's circumference... that's plenty of work and time needed to finish the joint. :-)
From this standpoint it's well understandable that they're searching for an improvement.
However, that's all based on assumption. Hence, it would be great if polka would provide you a/o us with some more information or could clear this up a bit more in detail.
I'm sure you would be the absolute right one, to point him in the right direction with this interesting application.
Thanks!
Stephan