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#204082 - 11/09/11 11:29 AM Securing 3/8 rod to overhead concrete
sparkync Offline
Member

Registered: 10/17/02
Posts: 811
Loc: NC
Have a job tying in a big chiller. They moved out the old one and brought in a new one. There are 2 sets of 3" emt fed from overhead with (3) 500 MCM in each conduit and a ground in each one. I'm going to have to shorten the pipe overhead and re-feed them down to the new chiller. There are no supports right before it will have to go into the new chiller. I got some 3/8 rod and plan on using some unistrut to hold it, but am having a problem getting the right anchor bolt to go into the concrete overhead. I got a 3/8 sleeve type bolt and some 3/8" rod couplings, but the problem is the threaded part of the sleeve is 5/16" and the coulplings won't fit. I normally don't do this big stuff, but got the job through a friend. Any advise from you commercial and industrial guys would be greatly appreciated. Thanks a lot. Steve...

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#204083 - 11/09/11 11:36 AM Re: Securing 3/8 rod to overhead concrete [Re: sparkync]
HotLine1 Offline

Member

Registered: 04/03/02
Posts: 6804
Loc: Brick, NJ USA
A trip back to your hardware supply for sleeve anchors with 3/8 studs, as opposed to 3/8 hole diameter will solve this. You may also have to obtain the correct masonry bit for the anchors.

You also may consider mounting strut to the concrete, dropping rod down to another piece of strut, then you could use the anchors you have.
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John

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#204084 - 11/09/11 12:00 PM Re: Securing 3/8 rod to overhead concrete [Re: HotLine1]
sparkync Offline
Member

Registered: 10/17/02
Posts: 811
Loc: NC
John, that was my thought, but my electrical supply house didn't have any sleeves with 3/8 threads:( Kind of thought that was what they was supposed to be, "a supply house"
Thanks, I'll probably be looking at one of the other supply houses in the area.
PS. 3 electrical supply houses and none have a sleeve with 3/8" threads... I may have to go with 1/2" rod or something else. I must be doing something wrong:(


Edited by sparkync (11/09/11 12:03 PM)

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#204085 - 11/09/11 02:44 PM Re: Securing 3/8 rod to overhead concrete [Re: sparkync]
HotLine1 Offline

Member

Registered: 04/03/02
Posts: 6804
Loc: Brick, NJ USA
I used to get most of my hardware from WW Grainger or McmasterCarr. That was after the local hardware guys vanished as result of the big boxes.

The 1/2 & 1/2 combo may work, if ya can get your hands on the parts.
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John

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#204086 - 11/09/11 03:02 PM Re: Securing 3/8 rod to overhead concrete [Re: sparkync]
gfretwell Offline

Member

Registered: 07/20/04
Posts: 9045
Loc: Estero,Fl,usa
The big box will have a 3/8-18 Red Head.
(at least they do here). I am still not sure how good the "pull out" strength is.
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Greg Fretwell

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#204087 - 11/09/11 05:27 PM Re: Securing 3/8 rod to overhead concrete [Re: sparkync]
HotLine1 Offline

Member

Registered: 04/03/02
Posts: 6804
Loc: Brick, NJ USA
Greg:

If I remember correctly, the sleeve anchors have a greater pull out than the 'red heads'. Sparkync might also see if there is a local Hilti store (or salesman) down his way.

I had a reference cd with all kinds of pull out & other data, but....darn if I can put my hands on it now.
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#204088 - 11/09/11 06:08 PM Re: Securing 3/8 rod to overhead concrete [Re: sparkync]
Tesla Offline
Member

Registered: 06/16/04
Posts: 1280
Loc: Sacramento, CA
The typical Red Head powder driven pin can sustain 134 lbs per pin...

The typical 1/4" generic wedge anchor with 1.125" embedded can sustain 110 lbs per fastener...

So Red Heads are WAY under-strength for your situation.

Out my way anything as massive would require 3/8"-16 threads per inch...

If not 1/2" - !
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#204089 - 11/09/11 06:33 PM Re: Securing 3/8 rod to overhead concrete [Re: sparkync]
HotLine1 Offline

Member

Registered: 04/03/02
Posts: 6804
Loc: Brick, NJ USA
Data from www.concretefastner.com

1/2" sleeve anchor (3/8 stud) 2000 PSI concrete....tension 2200 lbs (4:1 safety factor = 550 lbs each)

same in 4000 PSI concrete....4350 lbs (4:1 safety factor = 1087 lbs ea)

Spacing distances between the anchors factors into the precise engineering calcs also, but you should be OK with this.

BTW, the website above also sells anchors.
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John

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#204090 - 11/09/11 07:00 PM Re: Securing 3/8 rod to overhead concrete [Re: sparkync]
gfretwell Offline

Member

Registered: 07/20/04
Posts: 9045
Loc: Estero,Fl,usa
We must have a terminology thing here. To me a Red Head is a sleeve anchor, not a shot pin.

http://www.itwredhead.com/mechanical.php
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Greg Fretwell

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#204091 - 11/09/11 07:36 PM Re: Securing 3/8 rod to overhead concrete [Re: sparkync]
HotLine1 Offline

Member

Registered: 04/03/02
Posts: 6804
Loc: Brick, NJ USA
Greg:

Terminology issues for sure!

I hope when I said 'Hilti', that was not taken as a powder type anchor. They also sell mechanical anchors.




Edited by HotLine1 (11/09/11 07:55 PM)
Edit Reason: Added comment re: Hilti
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John

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