Interpertation/History of 'Grade 5 or Better' 1

[JohnVAME]

Hello Structural Engineers - I'm an ME in need of guidance.

I am curious as to your interpertation of a Drawing that reads 'Grade 5 or Better' (in particular the Grade 5 ref. in a structural steel connection) for structural bolts. Without any other information, would you assume that means..

to have the material and mechanical qualities of:
SAE J-429 Grade 5 bolts?

If so - why do people use the SAE reference now-a-days when the ASTM seems to be the standard for construction in the US. Something historical perhaps? International?

Thanks!

 

[HgTX]

"why do people use the SAE reference now-a-days when the ASTM seems to be the standard "

For the same reason they still refer to AISI grades when AISI hasn't published a steel spec in 40 years.

Hg

Eng-Tips policies: faq731-376

 

[dbooker630]

I would say the statement refers to J429. At least in transportation SAE J429 or J1199 (metric) is still widely used but there is increasing use of ISO 898-1 for fastener callouts.

 

[unclesyd]

It is somewhat of a long story.
It wasn't too many years ago that most structural steel was erected using rivets instead of bolts. There initial confusion in the steel erection industries about the quality of fastener to use, so about everything that looked like a bolt and nut was used. SAE grade 5 was well known as good high strength fastener so a lot of the call outs used this as reference as a safety valve. It took several years for materials like A325 to become readily available and called out.
According to my sources there is still references to SAE Grade 5 being used in call outs for structural bolts.


Anecdotal:

Early in my career there was a large expansion taking place on site where numerous steel framed building were being erected. While closing out the last building myself and my boss were making a quick tour when I pointed out that there were two different types of fasteners in one connection. After he calmed down we discovered 3 different grades of fasteners used during the building erection. The worst was a HDG square head plow bolt where the iron workers had reamed the holes to make them fit. The whole structure had to hot bolted to eliminate the off spec fasteners at a considerable cost of time and money.

Over the years I got very familiar with our site and would still see an occasional off grade fastener in a connection.
Early on after consulting with the resident structural engineer it was decide to let sleeping dogs lie unless there were more than 3 in a connection.

 

[deanc]

JohnVAME

Apologize for earlier post. Should know better then to post when in a hurry.

Should of said:

Read ASTM A-449,that will help with what you are looking for. Also check this site.

http://www.boltscience.com/

 

[deanc]

More good info.

http://www.americanfastener.com/technical/grade_markings_steel.asp

http://www.uspto.gov/web/offices/tac/fqa/fqa.htm

There is some important info. in this act. Some jobs will spec. this.

 

[JohnVAME]

Thanks great replies!!

I was checking a drawing the other day and saw a A325 bolt with an SAE grade nut - which made my head spin!!

So, your opinion again please.. the members that are being attached to the building are to support light conveyors - approximately 1-2 kips in tension on an A325 - soo it's really over designed (the requirement was from an out dated government spec) - my sense is that it is not an unsafe condition - And I'm just asking for reassurance since I am not a structural engineer (nor do I have to approve these drawings and they were signed by another PE) - This is bad practice ..mixing SAE and ASTM and does not meet ASTM A325's specifications right??

I'm off to read some of those links and I just bought a book called 'What every engineer should know about threaded fasteners' - every hear of it?

 

[deanc]

SAE only,sometimes means "fine thread". Maybe OK,maybe not. Need a spec. number and if you get to the same place,no problem. Depends on the job requirments.

Bolts:

http://www.textronfasteningsystems.com/eng_tools_f/boltjointdesign.html

http://www.hexagon.de/dose/dose1e.htm

http://www.tcnj.edu/~rgraham/barrett/manual1-A.html

http://mrainey.freeservers.com/index.html

http://www.tribology-abc.com/default.htm

Few more great sites.