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Milling of Structural Steel Tubes

Milling of Structural Steel Tubes

Milling of Structural Steel Tubes

(OP)
I have a situation in which short (21") steel tube segments will be used to splice longer segments of steel tubing (round HSS). The short splice segments must fit inside the larger tubes. In order to do so, the outside diameter must be reduced. The fabricator proposes to do so by milling 1/2" thick material down to 3/8" thick.

I'm wondering if anyone has any similar experience or any comments on the validity of this process.

Possible Concerns Include:
-Voiding the applicable ASTM tests performed by the Mill.
-Possible introduction of micro-cracks due to elevated temperatures.
-The work is beyond the scope of repairs allowed by ASTM A6 (is this a problem?).
-Surface roughness (this will be uncoated material embedded in soil, so corrosion is a factor - although corrosion allowances have been applied.
-Otherwise altering the mechanical properties of the material.

RE: Milling of Structural Steel Tubes

It sure seems like an expensive way to do it.
"Voiding the ASTM tests", I don't think would be an issue so much, but the finished product/assembly is likely not covered by any standard.
I don't think A6 applies to structural tubing, would have to check, though.
Will this all be welded up, or does it all stay loose and then get buried?

One idea that comes to mind is to cut a lengthwise slot in the tubing, then force it to a smaller diameter and re-weld. Not that I've tried it.

RE: Milling of Structural Steel Tubes

What diameter of HSS are we discussing here? Can you just have specific diameter HSS made from plate?

RE: Milling of Structural Steel Tubes

If the pieces to be milled aren't annealed first, they will "move" on you (warp, twist, etc.), and make inserting them into the larger tubes more difficult - especially if the fit is close (or tight). Machining them will release pent-up stresses which will cause them to move.

Thaidavid

RE: Milling of Structural Steel Tubes

(OP)
Cold-rolling the tube out of plate and welding the seam was considered. Actually, that's the reason fabricator is now milling the tube - to get away from the welding. CJP welds along the seams were problematic.

Thanks - all for your input and feed back.

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