Evaluation concerning tolerances when placing beams inside of each other

[SteelAndSteel]

Hi,
Two beams one 60x60 and another 60x60 beam with a welded 8 mm sheet shall be placed inside a 500mm long 140x70x4 beam, see the attached picture. The material for all beams is S355J2H. I wonder if it will be a good fit. When I am checking the tolerances (EN 10210), I can see a scenario where it doesn't work, but I don't think it is probable. What do you guys think?

 

[KENAT]

Not a hardcore structural guy or familiar with that standard but...

Where is the potential problem in stack.

If horizontal then can thinner sheet be put in instead if required?

Posting guidelines faq731-376

http://eng-tips.com/market.cfm?

(probably not aimed specifically at you)
What is Engineering anyway: faq1088-1484​

 

[SteelAndSteel]

HI

you can find the tolerances here:

http://www.sicamtubi.net/PDF/ENG/QUADRI/10.pdf

For BEAM 60x60 cross section
Max outside dimensioner
60->60.6
60,6+60,6+8=129.2
Hence
60,6x129.2

For BEAM 140X70X4 cross section
Min outside dimensioner
140-> 138.6
70 ->69.3
Max thickness:
4*4.1= 4.4
This means that the min inside dimensions is:
60.5*129.8

Beyond this i have straightness (which gives like 1mm), twist and squareness of sides.

So it wont fit in the worst case scanario (that all tolerances stack in the wrong direction), but should i be worried if i do like 20 pieces of these. I could increase the size but i want the slack to be as small as possible

 

[tbuelna]

If the tubes are roll formed and welded there may also be some weld drop protruding at the the back side of the weld seam that you need to account for. The weld seam is usually along the middle of the wider wall, which would be the top or bottom wall in your sketch. I have seen some heavy wall welded tubes where this weld drop was 1.0 to 1.5 mmm in some places. And with heavy wall rectangular rolled and welded tubes, the wall where the weld is made always seems to be bowed out way more than the spec tolerances allow.