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02-22-2008, 09:14 PM #1
How long to fit and weld a DN250 or 10" slip on flange?
I'm dealing with a weasel contractor and I need another estimators opinion.
Using John Page's manual I get a, labor only, breakdown, per flange, that looks like this:
DN250 (10") ASTM 106B std wt pipe & Class 150 slip on flange.
Handling, into and from the shop is not included in this calculation.
Flame cutting 0.56 hrs.
Assembly, tack welding, manual welding (GMAW or MIG) with 3 X 9mm (0.35") fillet welds 5.3 hrs.
Supervision & visual inspection are included in the 5.3 hrs.
NDT & blast/paint are not included in this calculation. There is no PWHT.
Where did I go wrong?
Thanks in anticipation.
02-22-2008, 09:53 PM #2
Wow! Thats a long time per flange...I see you have flame cutting - what is being cut? Also, you state three 9mm welds - I know two are generally used (one inside, one outside), where is the third weld?
To give you an idea of time, we use a 10" RFWN 150# to sch 40 as a time basis, for bench work on short pipe sections where we can use a positioner. We figure 1-1.25 hours of weld time, which includes tack welding, feathering 4 tacks, short arc open root, dress starts & stops, one hot pass and one cap pass with FCAW. These are ASME code quality welds and procedures. Granted, the positioner cuts a ton of time, but not sure where the 5.86 hours would come in your calcs.
Another way to look at it...figure out how many pounds of weld is required for your three 9mm welds...should be about 0.24 pounds per foot. Figure a 25% arc on time for your welders, and calculate pounds per hour desposited based on your process. You should be able to come up with a ball park idea of how much time it should take based on the three welds.
If you were close, we would be happy to do this work for you and charge 5.86 hours...heck, at those labor times, we could ship them to you and still make a killing!!!!
02-22-2008, 10:40 PM #3
maybe that's assuming you're only welding with a machine with 20% duty cycle, only welding 2 minutes out of every ten?
02-24-2008, 08:13 PM #4
Frustrating aint it?
The noise you hear is me grinding my teeth!
The flame cutting is a square cut to length, I'm in the Northern Territory of Australia, out in the boonies and thats the way they do it.
The three welds are an outside root, outside cap and an inside run. As I see it total per flg, say .936kg. With a welder, on arc, efficiency of 60% that gives me about 20 min of weld time (excluding setup & tacking). The rest is down to weak management who are bluffed by a bombastic contractor. This is just one small example of the rorting that goes on.
SteveinAZ, I think I could get you to do them and I'll come over for paid vacation in AZ to pick em up and still be saving money!
02-25-2008, 07:30 PM #5
when i worked as a watcher of the blue light, a long time ago i might add, if i took 5.5 hours to flange a 10" pipe [1/4" wall] i would find myself either unemloyed or promoted to manager, and that was rooting with high penetration cele rods, clean and capping, bad day in the rain with tent/puddle , space with stubs 1 1/2 hours including prep and cleanup.
that was with an old [ but i loved it lincon ]
the NDT boys could bomb it and read the results in 35 mins [ but they had a kodak processor in the back of a van ]