anchor bolt+luck nut

[farzam]

Hi All

Regarding erection of one column(Dia=3700mm, overal length=35150mm) at site,I found a problem that the bolt extention beyond the nut(thread part)is not sufficient to consider another nut(luck nut).Contractor made 2 comments:first,using spot welding between nut and top plate(anchor chair),and the second, using another nut beneath top plate.
Its my pleasure to recieve your comments about these 2 mentioned items.

Thanks in advance

 

[arto]

How about using a "bent tab lock washer" - sheet metal bent up agains nut flat & down against plate edge?

 

[farzam]

Dear arto

do you have any experience about using "bent tab lock washer" at site?because I dont.may i have your idea about two comments mentioned by me?

Thanks a lot

 

[unclesyd]

Isn't a double nut on anchor bolt, especially for a stack also used to effectively make the nut longer to prevent stripping of the nut. Supposedly thread deformation will let more area come into play.

 

[farzam]

Dear friends

Just i wanna know that have you ever heard about using second nut beneath the top plate of anchor chair for extension of contact surface of thread part?

Thanks in advance

 

[vpl]

farzam

I am having difficulty visualizing this. If you don't have sufficient bolt length to put a second nut at the end then how will adding a second bolt under the top plate work? It seems you would then not have enough thread engagement for the final nut?

What I understand is:
NOW

bolt head
top plate
column (through which bolt goes)?
bottom plate?
nut
lock nut if there was sufficient thread

PROPOSED

bolt head
top plate
nut
column
bottom plate
nut



Patricia Lougheed

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[11echo]

I've never seen a double nutted anchor chair. First off it would be hard to retro-fit the bottom nut on an existing piece of equipment(below the chair plate). Secondly it would probably be extremely hard to get a wrench in to tighten the bottom nut.
I would suggest using a "bellville" washer. It's a "cone type" lock washer, semi-pricey too! Check the link below, my $0.02! ...Good Luck!

http://www.rctek.com/fixings/bellville_washers.html