How to lengthen short anchor bolts
How to lengthen short anchor bolts
(OP)
I am installing several exhaust systems, each weighing 15,000 pounds on existing pads with existing threaded anchor studs. 1.25 dia x 6.
Some of the studs are short preventing full nut engagement.
What are the best practices to extend the length of the bolts?
Some of the studs are short preventing full nut engagement.
What are the best practices to extend the length of the bolts?





RE: How to lengthen short anchor bolts
http://www.sigmatool.com/t-nuts/2way-t-nuts.html
You would need appropriate clearance holes in the clamped parts.
Or, you can use a turnbuckle style long nut:
http://
You probably don't need the long middle section shown here, so just use view it as a conceptual diagram.
Regards,
Cory
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
RE: How to lengthen short anchor bolts
http://www.cns-sales.com/product.html
RE: How to lengthen short anchor bolts
Regards,
Cory
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
RE: How to lengthen short anchor bolts
If I understand the question correctly, I believe dennis problem is that he has equipment that has holes in the base for 1 1/4" diameter anchor studs. What he needs to do is extend the 1 1/4" diameter rod.
I am assuming that he doesn't want to enlarge the holes in his equipment base. It appears to me that to use coupling nuts or turnbuckles you would need to enlarge the holes. The T-nut looks like it may work if the holes in the equipment base are oversized to allow for field adjustment.
I believe dennis is looking for a method to extend the studs by welding or other means.
I have heard of people welding additional rod length on to existing anchor bolts. My experience is of the use of full penetration welds to make rebar splices. I would think dennis' problem would be similair.
RE: How to lengthen short anchor bolts
The idea with the coupling nut is that you would then position your part with its hole over the coupling nut, then use a bolt to clamp the part to the coupling nut/anchor stud combination.
Or, if that doesn't work, a T nut could be used.
Usually threaded fasteners are heat treated to relatively high strength. Also, they have closely controlled dimensions. Welding ruins both of these, so it usually isn't recommended for fasteners.
Regards,
Cory
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
RE: How to lengthen short anchor bolts
Any chance the anchor rod can punch throught the concrete because embedment is too great?
Dik
RE: How to lengthen short anchor bolts
Putting Human Factor Back in Engineering
RE: How to lengthen short anchor bolts
threads are engaged?
I assume this is strictly a tension
application. You might have enough
threads in contact anyhow.
RE: How to lengthen short anchor bolts
Yes, the anchoring puts the bolts in tension.
Most nuts engage all the treads so the threads are even with the top of the nut.
A few bolts are short and their nuts engage about 50% of the nut height.
The bolts are 1.25dia x 6 coarse. There are 8 per unit.
I wish I knew how to write you directly.
Also I have two conflicting answers -- one says weld, another says don't weld.
RE: How to lengthen short anchor bolts
RE: How to lengthen short anchor bolts
Have you thought of drilling new holes in the base plate and using post-installed anchors? No weld problems, no extending nuts or worrying about having enough room for this or that, just cut off the bolts that are too short and put in some new ones. The question then becomes is drilling a new hole OK, will the new configuration of bolts be impractical, is the area accessible, and so on.
RE: How to lengthen short anchor bolts
(The new units are in design so we can add more holes to the base rings so new anchors can be installed.
We will do a wind load and seismic analysis even though the pads are in place to test our customer's assumption that the old pads are adequate since the weights are about the same as the old units. We may add bolts regardless.
Thank you.
RE: How to lengthen short anchor bolts
Dik
RE: How to lengthen short anchor bolts
your particular situation to see if welding can
be used. If it is low carbon like A36 material,
I would think that welding would be ok. If it were
high strength studs or anchor bolts, you would have to degrade them because of the welding drawing out some of
the apparent hardness. I would be greatly troubled if
two of these were side by side or on the same side of
the bolting pattern.
RE: How to lengthen short anchor bolts
RE: How to lengthen short anchor bolts
Conflicting answers may come from lack of information and datails and different experience of people involved. I want to apologize for short answer last time, but I was pressured by time and just wanted to caution against any technical half solutions to extend the anchor bolts.
What I was intending to point out is:
1. Do proper design of any solution you implement: welding or no welding, irrespective.
2. Know the materials involved, do not take shortcuts there.
3. Consider new anchor bolts, avoid extensions, they tend to be weaker than monolythic bolt.
4. If you find new bolts weldable and it is the feasible option, weld, but, again, make sure your weld is designed properly.
5. Don't assume, check all calcs again.
6. I can give you complete solution but I need details, drawings and charge number. :)
7. In the meanwhile you are an engineer and responsibility for due diligence in resolving the problem lies with you, no matter what advise is given on the forum.
And thank you, UcfSE, for doubting. Doubt is a basis of good, responsible engineering.
Putting Human Factor Back in Engineering
RE: How to lengthen short anchor bolts
RE: How to lengthen short anchor bolts
I have heard of the above being down with steel column base shoes. I'm not sure I would consider plug welding the nut when the bolt is subjected to tension. However with a four anchor bolt base shoe for a column loaded only with gravity loads I might give it some though.
RE: How to lengthen short anchor bolts