Diametric orbital welding equipment?

Hello,
I used a brand "Dimetrics", and was QC (CWI also) on a similar job approximately ten years ago with the same material specs that you quote, although I don't know what diameter/wall thickness you are using. We ran into problems in that we did our weld procedure quals during warm weather and then with schedule and city official delays we ended up fabrication during the cold of winter. Most of the spools were welded indoors and then moved to a trench for field welding. We did anticipate pre-heat and interpass so the base material was not a problem. I had worked 13 years or so as a engineering technician (welding) at a US Navy Shipyard that was closed down, so I had background on procedures and orbital and mechanized as well as manual welding. What was a problem was apparently the Dimetrics machine had an inherent problem in that the electronics apparently did not perform well in field conditions (cold). It seems that it was more set for "shop" fabrication applications. We ended up building a moveable "shelter" and we had flexible electrical heating pads for pre-heating pipe to remove the chill and to also keep the weld area dry. We ended up using the heating pads to keep the machine warm and the weld defects went away. What was criminal was that others knew about the problems with the machine and neglected to tell us, they wanted to make money off of the rental of the machine. Long story short, we ended up hand welding many of the joints because of the city official problems.
However, I would recommend "Arc Machines" or AMI equipment as relatively robust equipment, as since I have been QC on many jobs since then and we have had quite good sucess with that brand.
If you need any other information my email is:
snipped-for-privacy@yahoo.com

Or MK Products.

One thing to remember, different pieces of stainless steel often have dissimilar electron emissivity even from the same heat. This can cause the welding arc to stray from the centerline if you're thinking of doing an autogenous circumferential seam weld on these pipes. You're probably in the thickness range where it looks attractive. There are a couple of manufacturers that make fittings that have mini sockets to avoid that difficulty. Similarly, if you're looking at 304 stainless, watch out, because autogenous welds aren't particularly strong. There's a reason why one uses 308 stainless to weld 304 to 304. It's too long to go into in this forum, but it ain't as easy as it looks to make good, safe, reliable, autogenous stainless to stainless weld joints. I'd recommend going to Parker Hannafin and seeing if they've got any of those fittings in 308 or maybe 316.
I like the AMI stuff too. I don't think there's a comparison between Dimetrics and AMI. I think you'll get better service from AMI too.
J