you have me totally lost
24" ID pipe???????
large pipe is measured by OD
wall thickness is 4.9"??????
24" OD pipe sch 160 is 2.343" on my tables
and that on my tables is the thickest std pipe size
the groove angle of 60 degrees sounds large to me
this sounds like a school question
or to bid a job
and need way more info for a job bid
and the correct info
start with welding process
then manual or robotic?
but I think you should go smaw 1/4" 7024
and make at least 80 man hours out of the job
and how many passes? ALOT
sincerely,
Kent

Well 4.9 divided by 3/8 would tell you the number of layers, however there is no possible way to answer the question about "passes" as you don't know how much metal is going to be deposited on each pass or how many passes per layer, and it is highly unlikely if not impossible that pass deposition would be uniform from root to cover while simultaneously maintaining a consistent throat dimension of 3/8".

Your cylindrical object doesn't really sound like a PIPE. 

As too how many passes.... your guess is as good as anyone else here.  Seriously. 

Better info: process, electrode, electrode diameter, volts, WFS, TS, rotation speed, is 3/8" the thickness or width or both.

Suggestion, find your electrode specification, should be able to find or calculate a volume of weld per minute.  Figure out the volume in your joint: 24 X Pie for circumference then calculate your triangle area and see what you get.  (may work on this later just for fun) 

You should be able to figure out how long it will take and how much electrode it will take, but, the number of passes- that may be more difficult.

He Is In Control, Have a Great Day,  Brent

Assumption SMAW:
- AWS/SFA A5.1 E7024 - 180% recovery;
- ø  = 6.0 mm;
- l = 450 mm (~ 50 mm stub).

~ 64 passes.
~ 26 hrs.

Don't ask for error bars.

Or, to quote 'welderbrent': "... guess is as good as anyone else here. Seriously." Unquote.