Torque of Bolt with Spacer in a Bolted Joint

[struclearner]

Are the bolts with spacers in Bolted Joint tightened to their maximum torque? The Clamping Force is transferred to members through spacer interface area with upper member. This does not cause high stresses due to less interface area due to spacer.
Thanks for your help.

 

[DrZoidberWoop]

The correct answer will depend on 1) your industry, 2) expected performance, 3) materials, and 4) code.

For example, in the structural steel industry, bolted joints have strength "penalties" or coefficients based on filler/spacer thicknesses. Some spacers, like thermal insulating pads (Fabreeka), have different creep properties than steel, and therefore affect the performance of a fully tensioned bolted connection (pg 7 of

https://www.seacolorado.org/docs/Thermal_Breaks_in_Structural_Steel_2023.pdf).

For situations like that, fully tensioned bolts are not best.

So I imagine there are similar aspects of bolting/fastening in other industries. The devil is in the details.

 

[SWComposites]

Yes, describe in detail the joint configuration, and also the application.

 

[CWB1]

Depends on the stiffness of the spacer. Steel sleeves capable of transmitting full clamping force are common, as are gasket materials that aren't. FEA can be very helpful in analyzing but if the joint is critical you have to test.

 

[iangineer]

Do steel sleeves have a number designation like bolts and nuts do? For example, I deal with SA-193 B7 bolts. I haven't been able to find any information on sleeves like that that would be known to be appropriate to use with B7 bolts.

 

[Tmoose]

I think some Navsea and other Military specs suggest suggest adding appropriate spacers to achieve a decent bolt L/D ratio, like maybe 7 ?
Like when bolting down the powerplant in a submarine etc.

 

[FacEngrPE]

ASTM F436 hardened washers are used with A193 Grades B7, B7M, and B16 bolts. A joint fitted with these washers will be very stiff, and can be torqued the same as a joint with no washers. If a "sleeve" is needed (better than a tall stack of washers) B7 and B16 machining stock is readily available.