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Torque control in bolt tightening

Torque control in bolt tightening

Torque control in bolt tightening

Looking for an inexpensive reusable mechanical device (i.e. DTI) to establish bolt tension.

Application: Setting conveyor belt tensioner bolts to install and monitor belt sag.

RE: Torque control in bolt tightening

Perhaps I'm oversimplifying but what about a torque wrench and a Skidmore-Wilhelm to calibrate the wrench.  As for the actual tensioning you could then procede with turn-of-the-nut method as specified in AISC.

RE: Torque control in bolt tightening

How about load using indicating washers and then regularly check the gap between bolt head and washer with a feeler gauge.


Andy Machon


RE: Torque control in bolt tightening

I am not sure what part of the tensioner you are working with, but MOST conveyor belts are not tensioned directly with the bolts, but by some gravity take up or spring loaded device.  Having said that, the few that I have set up with direct tensioning ,ie, the tensioner bolts connected directly to the take up roller, have had no method of checking the torque on the bolts due to the varying load on the  belts.  Also , tracking of the belts is directly related to the attitude of the take up roller, thereby negating any equalizing of the torque on the take up roller bolts. If the belts were ABSOLUTELY true (not practical in the real world) it may be possible to use torque values to equalize the tensioner bolts, I , personally have found that conveyor belts vary a great deal from ideal.
In the field, most tensioners are oversized and we use prescribed tensioning techniques, but what usually happens is that you simply "get up on them" until the belt sag is where you want it and it tracks somewhere near true.
Again , I am not sure from your question if this    will be of any help.


RE: Torque control in bolt tightening

Before the widespresd use of TS bolts, load indicator washers were a common sight on the job site.  It has been my experience that even with proper training and journeyman ironworkers doing the bolt up, it was easy to install the washers incorrectly.  The feeler guages provided by the bolt company were usually lost the first week and inspection ended up a visual thing (not necessarily a bad deal).  It was also common to keep a couple of smashed washers in your bolt bag, just in case you had a connection that you could not get a gun on (listen , boys , this IS the real deal here!).  I always instructed my crews in the proper use and installation of load indicators ( which REALLY made me popular?) and the need to do it correctly the first try.
I personally find load indicators a pain in the neck.  Just more parts to look after.  A good , calibrated torque wrench in the hands of one of my apprentices was all that was ever necessary to keep up with the inspectors requirements, even on the biggest jobs.  With the advent of TS bolts, even that was not necessary. (Keep in mind that TS bolts are definately not the perfect solution on a construction site, just the best  so far. Quiet, easily inspected but, resulting in bad connections if not properly bolted up and with ALL THOSE LITTLE ROUND THINGS EVERYWHERE!)
I am old enough to have been on a job that used RIVETS!!!   I didn't know much then, but now I look back with a certain nastalgia.  Rivets ARE a macho thing , you know. Of course, I am somewhat deaf in my right ear---but that's another story----


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