Drilled Holes vs Tourched/Flame Cut Holes
Drilled Holes vs Tourched/Flame Cut Holes
(OP)
I am working on a project that requires holes 1-5/16" dia. 1/2" deep to be drilled in A36 steel. These holes being drilled are in the field, so we do not have the ability to use a drill press.
The contractor performing the work would like to tourch cut the holes instead of drill them.
Is there any reason the holes should not be tourched/flame cut?
The contractor performing the work would like to tourch cut the holes instead of drill them.
Is there any reason the holes should not be tourched/flame cut?





RE: Drilled Holes vs Tourched/Flame Cut Holes
tell them to look into a magnetic drill with a rotary broach attachment.
drills much much faster than a standard drill bit, especially in larger sizes
RE: Drilled Holes vs Tourched/Flame Cut Holes
How neatly/accurately can they make the holes with the flame? Does it meat required tolerance?
KENAT, probably the least qualified checker you'll ever meet...
RE: Drilled Holes vs Tourched/Flame Cut Holes
RE: Drilled Holes vs Tourched/Flame Cut Holes
neat tool and fast and clean
RE: Drilled Holes vs Tourched/Flame Cut Holes
RE: Drilled Holes vs Tourched/Flame Cut Holes
What you guys have said is help full with the rotary info. But i am looking for some theory behind why you should not tourch cut. I am an engineer and want to convey some theory on why tourch cutting is not recommended.
Talking throught the application, specifically the part about the holes need to be snug around the anchor bolts have given me some reasoning as why tourch cutting is not recommended but i would like more.
RE: Drilled Holes vs Tourched/Flame Cut Holes
This is the other big reason I know of that torch cutting can be a problem apart from the tolerance issue.
Like I said I'm not familiar with US grades but you're effectively applying some kind of uncontrolled heat treat to the surrounding material. What will this do to the mechanical properties, or in some cases appearance?
KENAT, probably the least qualified checker you'll ever meet...
RE: Drilled Holes vs Tourched/Flame Cut Holes
http:
for more options on rotary broach.
Depending on the location, you might be able to find a hydraulic punch with sufficient capacity.
This one comes close:
http://www.hellerson.com/hydraulic_punch.htm
You don't want to flame cut because:
You have no idea what the HAZ properties will be, or how large it will be.
The hole will have nasty edges that will be where the cracks start.
RE: Drilled Holes vs Tourched/Flame Cut Holes
KENAT, probably the least qualified checker you'll ever meet...
RE: Drilled Holes vs Tourched/Flame Cut Holes
The heat may also (will) change the properties of the steel.
If you are building "junk" then this is just fine - but if you are building something for real - don't allow it
RE: Drilled Holes vs Tourched/Flame Cut Holes
Don
Kansas City
RE: Drilled Holes vs Tourched/Flame Cut Holes
RE: Drilled Holes vs Tourched/Flame Cut Holes
We are in the process of locating an annular cutter, and we will begin cutting tomorrow.
RE: Drilled Holes vs Tourched/Flame Cut Holes
Regards,
Mike
RE: Drilled Holes vs Tourched/Flame Cut Holes
Is it possible to field weld some clips with the correct size hole? Under some circumstances this would provide quicker, better looking results.
The other option I see is to torch the holes and weld a heavy "square washer" with correct hole diameter on top of existing material.
RE: Drilled Holes vs Tourched/Flame Cut Holes
Obvious answer #2: fire hazard
Obvious answer #3: it will never be round or in the correct location.
Obvious answer #4: It is easier to make a mistake.
Obvious answer #5: Your customer will thing you done everything the cheap/easy way.
ISZ
RE: Drilled Holes vs Tourched/Flame Cut Holes
RE: Drilled Holes vs Tourched/Flame Cut Holes
rmw
RE: Drilled Holes vs Tourched/Flame Cut Holes
RE: Drilled Holes vs Tourched/Flame Cut Holes
It would take a good ironworker a few minutes to mark the hole and burn it out with a nice enough finish to structural work.
If your not sure of your guys then drilling may be the way to go but I would let my guys torch the plate with no concerns.
RE: Drilled Holes vs Tourched/Flame Cut Holes
we do not have the concrete under the steel when we are cutting the holes so we dont have the isssue of dulling the blade on the concrete. And we are limited with space so welding a clip on the side is not possible.
A flame cut hole and heavy square washer plate is something we might consider.
RE: Drilled Holes vs Tourched/Flame Cut Holes
If you "heard" it on the internet, it's guilty until proven innocent. - DCS
RE: Drilled Holes vs Tourched/Flame Cut Holes
The mag drills with shell cutters are fantastic little dealies- we've got quite a few of them in our shop. But the torch is king on a site. No cord to worry about etc., and far quicker in the right hands.
RE: Drilled Holes vs Tourched/Flame Cut Holes
RE: Drilled Holes vs Tourched/Flame Cut Holes
Since you asked. Steel is iron with carbon in the lattice. Heat can make the carbon come out of the lattice and lead to graphitization on the surface. That can be very important when brazing to laser cut plate. In this case I think it would be marginally relevant at best.
Remember the haircut rule. You can lose weight by getting your haircut, but how important is it really.
Thomas J. Walz
Carbide Processors, Inc.
www.carbideprocessors.com
RE: Drilled Holes vs Tourched/Flame Cut Holes
There are two structural connections: bearing and friction. Bearing connections will resist load with the bolt actually bearing on the connected material. For the bolts to equally share load and keep connected material stresses to within the allowable it is necessary for the hole/bolt arrangements to have the same tolerances such that they all engage at the same time. I won't go into friction connections.
Burning the holes in will leave burring and uneven or irregular surfaces that will need to be reamed anyway for good work. Any work not reamed will leave potential micro-cracks in the irregular surface that can in cases propagate.
Usually a Hougan Drill is around somewhere just need the proper motivation for the contractor to bring it out....don't pay him until he does!
Having said all that, sure there are sites where no inspection is performed and ironworkers will unabashedly use the gas-wrench to fix things. However, when an engineer is on site and this is the area under consideration it must be dealt with. Bad practice is bad practice even if the ironworker says he's been doing it that way for 20 years.
Regards,
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Qshake
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RE: Drilled Holes vs Tourched/Flame Cut Holes
Cheers
Greg Locock
SIG:Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.
RE: Drilled Holes vs Tourched/Flame Cut Holes
...when they are blind.
Gosh they are funny around here.
RE: Drilled Holes vs Tourched/Flame Cut Holes
A36 structural steel is generally referred to as "mild steel" or "low carbon steel" (ie. less than .25% carbon). Its low carbon and alloy content makes it easy to weld, makes it ductile, gives it low tensile strength, and makes it relatively unresponsive to quench hardening. So if you're going to cut a hole with a torch, A36 is the best steel to do it in.
Of course, having said that, why would you want to make holes using a torch in the first place? A36 is a very soft and machineable metal. Why not use a magnetic drill press? You'll end up with nice, clean, round, accurate holes, instead of jagged, inaccurate holes with lots of slag around the edges. And a warped plate to boot.
And besides, how do you control the depth of a hole (to 1/2"?) using a torch?
RE: Drilled Holes vs Tourched/Flame Cut Holes