Well, no, probably not. But if the 3" thin wall tubing is longer than about 6 or 7 inches, you will need a Steady Rest. However, that would also be true of Ernst's 9" South Bend or of my 12" Atlas Commercial.
Also, how you would do that safely with any machine would depend upon how long the pipe was and how much you are parting off. If for example you are parting off the closed end of a welded construction hydraulic cylinder, you could probably do that on the 954 if the piston rod is no larger than 3/4". The spindle bore on all of the Atlas machines except the 6" ones is 25/32". So 3/4" is the limit that you can stick up in or through the spindle bore. If the rod is larger than 3/4". then it depends upon how much of the rod has to stick out in order to get the piston safely out of the way of the parting tool. That's almost certain to be too much for the light duty chucks that you normally find on an Atlas 9" or babbit bearing 10". One other problem is that unless the 954 you are thinking of buying comes with a Steady Rest in good usable condition, you might find one on eBay this week or it could take two years of looking. Ones for the 10" and 12" turn up fairly frequently (typically more so on average than ones for the Logan's, Clausing's or South Bend's, which are the other brands I was thinking about earlier). And any of them are likely to cost you $150 to $300. Regardless of make, it seems to be a truism that any two or three significant accessories will cost as much or more than almost any of the bare lathes.
But the bottom line is, if you are buying a lathe (or anything else) to mainly do a specific job or type of job, don't let what looks like a good deal dollar wise talk you into buying something that can do it but just barely. Because by the second or third time you have to do it, you will have forgotten all about how good a deal it was and begin to dread the next job. I'm not yet saying that that's the case here, only that it could be.
