Zero tolerance bolt/pin holes according to ASTM Standards

[MichalisK]

My team is designing a pin connection which requires that the pin hole diameter is equal or 0.5 mm greater than the pin dimater. Is there any reference in ASTM Standards about a minimum pin or bolt hole diameter? Table 3.1 specifies the maximum bolt holes according to each bolt diameter but does not give any minimum limit. I would also appreciate if you can give me any guidance regarding the constructability of such zero tolerance pin/bolt connections.

 

[dhengr]

MichalisK:
Why do you need such a tight hole/pin fit? What other pieces/parts does this pin go through, and are the pin fits that tight in these parts too? Can you hold tolerances in the various parts well enough to make everything fit-up? When you mention ASTM stds. I suppose you are looking at their stds. for structural bolting and they are most worried about some max. hole slop which still allows a bolt or group of bolts to act together and with some consistency in a structural steel joint. The other bible-like std. is the “Specification for Structural Joints Using High-Strength Bolts,” by The Research Council on Structural Connections (RCSC). ASME and others will have some of their own stds. too.

There is nothing that prevents a press fit in the hole for a pin/bolt, as long as you design for this condition, and can actually build it and make it work. On bearing pins, a smaller difference in the hole and pin diameters actually improves the bearing stresses btwn. the two. That’s a Hertz bearing stress problem.

 

[Ron]

MichalisK....close tolerances such as you reference are rarely used in building design/construction, mostly because of cost and constructability. As dhengr notes, the bolting references provide guidance; however, the tolerances are mostly maximums that prevent loose and sloppy connections.

Bridge construction uses more pin-fit construction than buildings so try the AASHTO standards for tolerances.

 

[klaus.]

Usually the hole diameter is 2mm bigger than the bolt
for bigger bolt ( 1 inch or more)it is 3 mm






best regards
Klaus

 

[dozer]

Table 3.1? Is it just a coincidence that Table J3.1 in Manual of Steel Construction, 9th edition gives the nominal hole dimensions for bolts or is that what you meant? There are tons of ASTM standards and I'm only familiar with a small percentage but I can't think of what ASTM standard would give guidance in this area.

 

[MichalisK]

Thank you dhengr, Ron, klaus and dozer for your quick responses. There were some geometrical restrictions regarding the hole edge distance and that is why the hole had to be so tight. Since it is hard to achieve these pin/bolt connections from a constructability point of view, as you also pointed out, we decided to design a 33 mm hole (instead of 30 mm) for a 30 mm pin. This reduces the bearing strength at pin/bolt holes but it is still sufficient for our design.

dozer: Yes I meant Table J3.1 in Manual of Steel Construction indeed.

 

[klaus.]

that's good...no reduction of bearing according to Euro Code ....



best regards
Klaus

 

[hokie66]

Just a word of caution about oversized holes in pin joints when used in architecturally exposed steel where alignment is critical. A small amount of play in a hole can lead to unexpected geometrical results.

 

[klaus.]

3 mm more for a 30 mm bolt is NOT oversized.....it is standard ...




best regards
Klaus

 

[kingnero]

An excerpt of the EN1090-2 (structural steel construction standard):

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