Clevis with bolt

[enginerding]

Is it wrong to specify a clevis with an A325 bolt rather than the pin that usually comes with it?

 

[Bribyk]

If a professional engineer takes responsibility for it you're okay, unless you're said engineer and something goes wrong.

If you use a standard shackle and its pin the liability is on the manufacturer as long as the shackle is loaded/used according to their instructions and the users are trained in safe lifting practices.

There are also different shackle pin types available such as screw type, bolt type and cotter pin retained.

 

[msquared48]

I don't think that it is "wrong" per se, a little dangerous maybe in that the bolt substitution could affrect the load capacity of the clevis, or cause it to fail in a different mode than it was designed to do.

Mike McCann
MMC Engineering

 

[enginerding]

The Number 2-1/2 Clevis is good for 12.5 kips according to AISC 13th Ed. Manual. This is "a 3:1 safety factor using maximum pin diameter." The maximum pin is 1-1/2" diameter, leaving only 1" of total material (1/2" each side) at the pin-hole.

A 3/4" bolt has a strength in double-shear of 21.2 kips. This small hole for a 3/4" bolt will also result in a much greater amount of steel at the pin-hole. I was hoping to get about 16 kips capacity out of the connection. The table doesn't make it appear that I could use a Number 3 Clevis for a 3/4" rod.

 

[miecz]

The forged clevis could also fail in tension across the body, shear beyond the pin hole, dishing of the section beyond the pin hole, or stripping the threads at the head. I wouldn't put more load on the clevis than it's rated for. The 12.5 kip rating, by the way, is new. The old green book rated clevises with a 5 to 1 safety factor.

 

[JAE]

If a professional engineer takes responsibility for it you're okay, unless you're said engineer and something goes wrong.

Bribyk - that's got to be a good answer for almost every post on this site. Well done!

 

[dicksewerrat]

Get the heavier rated clevis. If you want to pick 16 kips get one rated 20 kips. the cost difference can't be that great. Probaly less than your time to post and read and answer.

Richard A. Cornelius, P.E.

http://WWW.amlinereast.com

 

[Bribyk]

Yeah, I guess my post wasn't all that helpful, was it? It just seems like a lot of posters want "the answer". If there were "answers", engineers wouldn't have jobs because no professional judgment would be required.

I'm not razzin' you, enginerding. I just laid the basic facts out there because you didn't provide much info on the application.

 

[csd72]

The threads in the bolt make it more susceptable to fatigue, also if it is in bending then it is much weaker.

Not really much judgement required if you do all the numbers.

 

[miecz]

The threads in the bolt make it more susceptable to fatigue

The old steel manual noted that the pin had to be checked for bending and that clevises were often used in rigging and so were subject to dynamic and impact loads. These notes have been deleted from the new manual and the safety factor has dropped from 5 to 3.

 

[PaulDoherty]

Full disclosure: My company is a manufacturer of forged steel clevises.

I second dicksewerrat. Go with a #3 clevis - threading for 3/4" rod is not a problem. Only issue you may have is that our #3 forging comes out of the trim die with a hole for a 1" pin so a 3/4" bolt would not be appropriate. The other guys forge their clevises without a hole so your 3/4" bolt would be OK if you sourced from them.

The only issue I have with using a bolt in place of a pin is that I don't like threads in the shear plane and it's not like you can order bolts in any thread length increment that you desire.