Standard ASTM Bolt Seating Loss

[benjaminjones]

It seems a lot of hydraulic bolt tensioning companies refer to an industry standard of "% of Load In bolt after seating losses"= 1.01+D/L where D is the nominal diameter of the fastener, and L is the grip length of the fastener, with a minimum of 90% seated load (or 10% loss).

Does anyone know if this comes from a specific ASTM standard?

It looks like this is an empirical formula so I'd like to know what data (bolt sizes, threads, etc.) were used in the data. Thanks

 

[CoryPad]

I didnt see the equation in Kulak's Guide , the RCSC Specification , AISC 360-05, nor EN 1993-1-8, so that is a mystery.

 

[unclesyd]

I first heard about this in the 770's from Mr. Biach, designer of the Biach Bolt pensioner, during a seminar and demonstration at our plant. he had just returned from the Far East where he had been call back due to anchor bolts on a new reactor were loose. he stated that they were properly tightened 6 weeks before and in that time they had relaxed, some completely. They were retightened and checked the next day or two and there were still loss preload. He stated after the third tightening they stayed put.
Several years after this I was talking to the Superbolt people and they mention that the developer of the MJB nut had encountered what he called "The Virgin Bolt Phenomena" it was essentially the same a Mr. Biach had found previously. Superbolt did have a paper on their site with all the details. I'm try to find my copy.. You might call Superbolt to see if they still have the paper available .

We have experienced this in some batches of H-11 bolts ¾”, we use. It appears that once the bolt cycles the relaxation is all over and done with. One just has to know it happens and look out for it and correct it.

 

[Tmoose]

100% loss of preload did not happen at the fastener's thread interfaces. Something slipped down in the ground. The variations in design of embedded anchor bolts (J-hook, washer and nut, welded cage), and the potential for installation errors ( grout filled cage, sometimes by design, sometimes by accident) conspire to bespoil the natural beauty of a luxuriously l-o-n-g anchor bolt. The slippage and creep potential of an embedded anchor is enormous compared to a straightforward all metal joint.

 

[unclesyd]

I probably miss quoted Mr. Biach it should have been some looked like they had never been tightened. The referenced bolts were at a Philippine Nuclear Plant. They were part of a massive hold down system and if I recall a diameter of 8". There was also a paper written about this, don't know the publisher.

 

[unclesyd]

Here is reference to the “Virgin Bolt Phenomena” by Stienbock. Don’t know how to get access. The Linda Hall Library may have it.

http://www.boltscience.com/pages/references.htm