I don't know how I missed this one!

If this is still a pressing concern, please let me know and I will certainly help you.

Meanwhile, I've attached a compressed Excel file that'll allow you to work out some of these values. It's locked, therefore you'll have to use the Excel menu to close it once opened.

One thing to remember: "Torque" is only a measurement of the resistance of input force. It does not and cannot indicate how "tight" a bolt is! You may very well calculate a certain torque to meet your percentage-of-yield requirement. In doing so you will have had to assume a certain friction factor (K). There are myriad factors, most unknown and practicaly uncontrolable, which impact the K factor. Therefore, a "properly" torqued bolt (even if tightened with a calibrated torque wrench) could either be too loose (and the joint may fail) or, too tight (and the joint may fail)

Certain applications (mill structural bolts, for example) require very high preloads. To leave the reliability of such fasteners to chance by simply torquing them without any verification of actual preload is very dangerous and risks the availability of the plant. Bolt load verification is accomplished by measuring the fastener's elongation and then "tuning" the bolt accordingly. It's a highly accurate method but, granted, does require a degree of operator skill to be effective (this is what keeps us quite busy!)

I hope that this has helped.

Attachments

hevï_boltworksheet _ 2.64_metric-imperial(locked) (ZIP)

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Sorry folks, the previous file wouldn't "open". Here's one that should...

Attachments

hevï_boltworksheet _ 2.64.1_metric-imperial(locke (ZIP)

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Originally Posted by jmalbrecht

I don't know how I missed this one!

If this is still a pressing concern, please let me know and I will certainly help you.

Meanwhile, I've attached a compressed Excel file that'll allow you to work out some of these values. It's locked, therefore you'll have to use the Excel menu to close it once opened.

.......

I hope that this has helped.

I, for one, am very glad you saw this one in the end.

I've downloaded your worksheet::::: with thanks. ■

HI,

sir i am not able excle sheet

regards

rk ■

Hello,

If you're having problems opening the spreadsheet, I think that the solution is to save the file first and then unzip it. I've tried it and it actually works on both files ■

Originally Posted by jmalbrecht

Hello,

If you're having problems opening the spreadsheet, I think that the solution is to save the file first and then unzip it. I've tried it and it actually works on both files

Thanks much it saves me a lot of work and eye strain :^).

I no longer have the bolt torque sheets from Joy so this helps. ■

An aeronautical engineer will select the correct grade of bolt, nut & washer and tighten the joints in the recommended sequence using a certified calibrated torque wrench. Then he prays and holds his breath.

A diligent mechanical engineer will select the correct grade of fasteners and ratchet them up, followed by a ring spanner and finally a bit of pipe over the ring spanner. Then he keeps his eye on it.

A civil engineer will select a bolt, an oversize nut and a washer if there's one about. He winds the nut on finger tight until the cross threading kicks in and then goes down to the pub while the rust sets in.

Well that's what we were told at one of our university dinners. ■

The previous post was very astute! However, although much, much better than simply relying on "torque" there are some issues with the angle of turn method. The prime problem is "having to rely on an unknown reference point"

On a "sprung" metal-to metal joint (ie where the flanges have rotated or are otherwise warped), one has to make sure that the joint is fully closed before marking the nut. Rotation of the nut just leads to closing of the gap a bit further. It does nothing to actually preload the fastener. The fastener may still be "loose"! Sometimes it's impossible to get access for a feeler gauge in these situations.

Obviously, on gasketed joints it's even more difficult to do this. Of course, some will say that this is offset by initially "torquing" the fastener and then marking it. However, one still has to contend with the innaccuracies of torquing at the beginning of the process: Marking the nut at the wrong point will result in inaccurate residual load.

In addition to the above, issues with load transfer when adjacent fasteners are tightened may still affect the integrity of the joint.

The best and most definitive way of ensuring proper bolt load is by measuring the stretch of the fastener after it's been tightened and then again, after all of the other fasteners have been tightened. Elongation is directly proportional to a fastener's preload (unless said fastener has been tightened to beyond its' yield point). Thus, regardless of the friction factors or geometric anomolies, the fasteners can be "tuned" accordingly to result in the proper preload!



* the spreadsheet also calculates elongation vs preload ■