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Shear-off bolted connection

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I would like to suggest that you consider "load indicating washers" as an 
alternate to the "twist-off" bolts.  HSB's with load indicating washers can 
be installed with ordinary tools that would not need to be imported into 

Load indicating washers have protrusions on them which are flattened as the 
HSB is tightened.  When a feeler gauge cannot fit between the bolt head and 
washer, the bolt is sufficiently tightened.

A. Roger Turk, P.E.(Structural)
Tucson, Arizona

You wrote:

. > Dear Colleagues,
. > 
. >   I need to find information about a type of bolted construction that 
. > involves bolts that have a spigot at the end of the thread which shears 
. > off at tightening when the required torque is reached.        
. > 
. >   Special power drivers are used to install bolts in this fashion.  I 
. > need to find out about purchasing and/or renting these machines.
. > 
. >   I got a hold of a brochure from RTB Tooling (Rapid Tension Bolts) which
. > talks about these tools but I don't have enough information (no phone 
. > number, etc).
. > 
. >   The description of how the RTB works is as follows:
. > 
. > "After the connection is fitted, the outer socket of the tool applies a
. > clockwise rotational force to the nut as the inner socket applies a 
. > counter clockwise force to the spline.  When the fastener exceeds the 
. > required tension, the spline end will shear".
. > 
. >   I would greatly appreciate any information on where to get a hold of
. > suppliers of this type of equipment, in the States or in South America.  
. > I'm looking at erecting a 10-story steel building with this system (1200
. > tonnes of steel involved) and I urgently need to price the purchase or 
. > lease of 13 of these power drivers.
. > 
. > 
. >