Comments on: Bolt Shear Strength Considerations

By: ben

ben — Fri, 23 Oct 2009 18:18:52 +0000

Herb, you will be better off with a grade 8.

By: David Benyon

David Benyon — Tue, 19 Aug 2008 22:48:58 +0000

There is a UK company called Bolt Science who have computer programs on bolt tensile strengths (there used to be a free time limited demo as well!) There is also a rule of thumb that puts shear strength as 60% of tensile strength. Put the two together and voila! Note however that antique solid mounted diesel engines can wreak havoc on their mounting frames and won’t be the least impressed with ones clever calculations! Salt can also give unexpected results as tests done a great many years ago on chains showed that they were weaker when immersed in seawater. Ideally the bolts should only be loaded to about 10% of their failure load, possibly 20% on a rough job.

By: Adam Oakley

Adam Oakley — Fri, 11 Jul 2008 17:55:59 +0000

Thanks for adding the helpful link, Eric. Even though this is from an automotive standpoint, it looks like there is some good information for industrial and construction applications.

By: Eric

Eric — Fri, 11 Jul 2008 15:30:17 +0000

I found this, which might help.

http://www.rockcrawler.com/techreports/fasteners/index.asp

By: Greg Lindsay

Greg Lindsay — Thu, 24 Apr 2008 15:50:48 +0000

@Herb: Due to liability issues and given the fact that Portland Bolt does not have any engineers on staff, we are not in a position to answer questions regarding the use of specific quantities, sizes and grades of fasteners for a specific application. Please consider consulting a structural engineer for assistance with this question. Sorry we couldn’t be of more assistance.

By: Herb

Herb — Thu, 24 Apr 2008 12:58:26 +0000

When a bolt is used in a sheer load is it better to use grade 5 or grade 8? I’ve heard that grade 8 bolts are harder and therfore more brittle. Assuming a good fit with no slop in the assembly or a slightly loose fit – say 25-30 thousandths.