drilling steel pipe - help please !

[airtight]

Tomorrow I need to drill approx 20 x 2 1/2" (63mm) diameter holes through the side of a 18" diameter steel pipe.

The holes are to take pins. I have thought of two ways to do this -

a) magnetic base type clamp on drill with a 2 1/2" cutter.

this would be the ideal way but the pipe grade is x52 steel , i think it will be to tough for the drill at that large diameter. steel thickness is 7/8"

or b) flame cut the holes and weld in machined bushes. A bit more work by the sounds of it having to machine all the bushes.

any ideas on how heavy going it would be drilling it?

i once drilled similar sized holes through 1/2" sa 516-70 and it bluntened the new cutter immediately. i dont think x52 is quite as tough as boiler steel though.

any help would be very gratefully received. thanks neville

 

[IFRs]

Use a STRONG mag or air powered drill, clamp the drill to the pipe and use a long lever arm. There are special coated bits. They look like milling machine cutters, about 3/16" thick and will go through your pipe like butter. I'll try to remember what they are called.

 

[unclesyd]

The best way to do this job as you describe is with a Rotabroach from Hougen.

Precision flame cutting with a jig is possible with everything thing depending on type hole and the precision needed.

http://www.hougen.com/mag_drills/mag_drill_index.html

You can rent these machines and just purchase the cutters.

 

[Cockroach]

Why not hold the pipe down on the bed of a radial arm drill press, mounted on Vee blocks? Then you can simply drill a pilot hole and go in with a 2 1/2 diameter spade drill.

The pilot hole can be something like 1/2 diameter, center punch the pipe OD at the desired location. This will ensure the drill doesn't skip, wander off location.

Just a thought.

Kenneth J Hueston, PEng
Principal
Sturni-Hueston Engineering Inc
Edmonton, Alberta Canada

 

[airtight]

Thanks for the replies. The pipe is 45 feet long and weighs approx 6000 lbs, and there are 2 to be done. Each with approx 20 holes. The main problem i have with these cutters is speed and cost. The last time i used them as i have said was on boiler plate and it went blunt after probably one hole.

I know x52 is a high yield, perhaps not as high as 516-70 boiler plate, but i am concerned that i could waste over $1000 of cutters and a lot of time. we are doing the job outside so dont have a radial drill, that would have been ideal!

 

[bentwings1]

I'd use a plasma cutter and weld the bungs in myself. A good welder should be able to weld these very nicely.

 

[CorBlimeyLimey]

How about a combination approach. Plasma cut the majority of the hole, then clean up with the drill.


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[MikeHalloran]

You will like the RotaBroach.



Mike Halloran
Pembroke Pines, FL, USA

 

[JStephen]

A516-70 plate is only 38,000 psi yield. I assume the "x52" material is a 50,000 psi yield? If so, it'll be harder than the A516-70.

 

[CoryPad]

I agree with unclesyd and MikeHalloran - look at a Hougen magnetic drill and their annular cutters.

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[unclesyd]

Here is a company that will do the work or sell/rent you the the tools to do the drilling job. Very simple to use clamshell machine

http://www.phalco.com/mirageMachines.htm

Here is the company that makes the tools that Phalco has.

Look at model DD1632

http://www.mirage-machines.co.uk/drills.htm

 

[CorBlimeyLimey]

airtight,
So what was your final solution? How did it work?


Helpful SW websites FAQ559-520
How to get answers to your SW questions FAQ559-1091