Flame Cut Holes

[lsmfse]

I've been asked several times about cutting holes in steel beams(Fy=36 ksi), 2"-3" diameter for plumbing lines. We usually don't allow flame cutting, however the fabricator says he can apply a compound to minimize the impact on the steel. Has anyone ever heard of this? We usually allow plasma cutters for these hole types.

 

[CWIC]

I have had the welding suppliers try to market this stuff with a number of my clients, but none of them have utilized this stuff. The fabricators/erectors typically use their best people to cut holes.

The application of a compound or the use of mechanically guided equipment to assist in the cutting operation involves "extra" work. But, they end up going back and grind to make these cuts comply anyway after the inspector has noted these in a report. Flame cut holes (OFC) are satisfactory when the required surface profiles are in conformance with code requirements.

Thats the problem, most fabricators/erectors will not take the time to make these cuts correctly. Please note this is not true of everyone. I have photos of textbook beam copes, reentrant corners and weld access holes that look as if they have been polished.

Another concern would be any cutting on jumbo shapes which require preheat and NDT (MT or PT).

With regards to your post, no I have not seen this compound in use. But if the RDP permits penetrations, I usually allow any method of cutting as long as the radii, suface profile and dimensional properties are code compliant.

If there is a concern of the use of OFC on any structural member, then the entire project would be suspect as this is the primary method for cutting, severing, gouging, etc.

 

[chicopee]

Would it not be better to drill the holes instead of flamme cutting?

 

[evelrod]

chicopee, a rotary broach could 'drill' the holes but at 2" to 3" holes????? You would need a LOT of room, the machines (Hogan, et al) are VERY expensive, heavy , awkward to work with in the 'overhead', etc. Burning the holes is now and has been the SOP. I recall no real problems aside the occasional need for welding in a tube sleeve in some of the larger holes or in hospital applications and such. Sleeves used to 'transfer loads', 'stop stress riser propagation' and, 'comply with regs.'---

Bottom line---What can I say in regards to possible incompetance of the contractor? Failure of the inspector to do his job? Unfortunately all TOO common an occurance.
Flame cutting is still more art than science so you simply must be SMARTER THAN THE TOOL!!!

Rod (when I was younger and steadier, the "torchmiester&quot

 

[chicopee]

Tube sheets on boilers have 2 and 3 inch holes for tube ends and these holes are rotary broached -"drilled"-.

 

[flamby]

Flame cut is very much SOP at least on hydroelectric sites. We use it on hydraulic gates, penstocks, claddings and etc. etc.

Of course the strength reduction issues are to be addressed by the structural engineer beforehand. Sometimes Post Weld Heat Treatment may also be resorted to depending on thickness and type of steel and steel-supplier's recommendations.

Flame (when I become older and useful, the "arc&quot